[A] There may be growth within the inhibition zone. The density of growth may vary from a fine haze to substantial growth (see pictures below). If any zone edge can be seen, ignore growth within the inhibition zone and read the zone diameter. | [1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[2] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [1] Colistin MIC determination should be performed with broth microdilution. Quality control must be performed with both a susceptible QC strain (E. coli ATCC 25922 or P. aeruginosa ATCC 27853) and the colistin resistant E. coli NCTC 13846 (mcr-1 positive).
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[4] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[4] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] Susceptibility can be inferred from the norfloxacin disk diffusion screening test. See Note
[1] Susceptibility can be inferred from ciprofloxacin susceptibility.
[C]  | [C] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance.
[A] Non-wild type isolates were not available when developing the disk diffusion method.
[A] Susceptibility can be inferred from the norfloxacin disk diffusion screening test. See Note
[1] Susceptibility can be inferred from ciprofloxacin susceptibility.
[C]  | [C] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance.
[A] Non-wild type isolates were not available when developing the disk diffusion method.
[A] Read the obvious zone edge and disregard haze or growth within the inhibition zone (see pictures below). | [1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[B]  | [B] Isolates categorised as screen negative can be reported "susceptible increased exposure" (I) to ciprofloxacin and levofloxacin. Isolates categorised as screen positive can be reported resistant to ciprofloxacin and levofloxacin.
[A] Non-wild type isolates were not available when developing the disk diffusion method.
[1] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported susceptible to amoxicillin. Isolates resistant to benzylpenicillin should be tested for susceptibility to amoxicillin or reported resistant.
[1] Isolates susceptible to tetracycline can be reported susceptible to doxycycline. Isolates resistant to tetracycline should be tested for susceptibility to doxycycline or reported resistant.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[2] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [B] Examine zones carefully for colonies within zones. Colonies should be taken into account when reading.
[5] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[5] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[C] Metronidazole resistance is rare, but inadequate anaerobic conditions may lead to false resistance. In case of resistance, confirm sufficient anaerobicity, species identification and antimicrobial susceptibility test result.
[6] Metronidazole resistance is rare, but inadequate anaerobic conditions may lead to false resistance. In case of resistance, confirm sufficient anaerobicity, species identification and antimicrobial susceptibility test result.
[1] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L.
[3] Isolates susceptible to ampicillin-sulbactam and amoxicillin-clavulanic acid may be resistant to piperacillin-tazobactam.
[4] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L. | [3] Isolates susceptible to ampicillin-sulbactam and amoxicillin-clavulanic acid may be resistant to piperacillin-tazobactam.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] Isolates susceptible to tetracycline can be reported susceptible to doxycycline. Isolates resistant to tetracycline should be tested for susceptibility to doxycycline or reported resistant.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [B] Examine zones carefully for colonies close to the zone edge. Colonies should be taken into account when reading.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[C] Read the obvious zone edges and disregard haze or faint growth within the inhibition zone. | [2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] There may be growth within the inhibition zone. The density of growth may vary from a fine haze to substantial growth (see pictures below). If any zone edge can be seen, ignore growth within the inhibition zone and read the zone diameter. | [1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Isolates categorised as screen negative can be reported "susceptible increased exposure" (I) to doxycyline. Isolates categorised as screen positive can be reported resistant to doxycycline.
[A] Susceptibility to azithromycin and clarithromycin can be inferred from erythromycin.
[1] Susceptibility to azithromycin and clarithromycin can be inferred from erythromycin.
[A] Susceptibility to doxycycline can be inferred from tetracycline.
[1] Susceptibility to doxycycline can be inferred from tetracycline.
[A] Susceptibility to azithromycin and clarithromycin can be inferred from erythromycin.
[1] Susceptibility to azithromycin and clarithromycin can be inferred from erythromycin.
[A] Susceptibility to doxycycline can be inferred from tetracycline.
[1] Susceptibility to doxycycline can be inferred from tetracycline.
[1] The breakpoints are based on epidemiological cut-off values (ECOFFs) and apply to oral treatment of C. difficile infections. There are no conclusive clinical data regarding the relation between MICs and outcomes.
[1] The breakpoints are based on epidemiological cut-off values (ECOFFs) and apply to oral treatment of C. difficile infections. There are no conclusive clinical data regarding the relation between MICs and outcomes. | [2] Metronidazole resistance is rare, but inadequate anaerobic conditions may lead to false resistance. In case of resistance, confirm sufficient anaerobicity, species identification and antimicrobial susceptibility test result.
[1] The breakpoints are based on epidemiological cut-off values (ECOFFs) and apply to oral treatment of C. difficile infections. There are no conclusive clinical data regarding the relation between MICs and outcomes.
[1] Inducible clindamycin resistance may occur in Corynebacterium spp. This can be detected by antagonism of clindamycin activity by a macrolide agent. The clinical significance is unknown. There is currently no recommendation for testing.
[1] Inducible clindamycin resistance may occur in Corynebacterium spp. This can be detected by antagonism of clindamycin activity by a macrolide agent. The clinical significance is unknown. There is currently no recommendation for testing.
[A] Non-wild typeisolates were not available when developing the disk diffusion method.
[1] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported susceptible to amoxicillin. Isolates resistant to benzylpenicillin should be tested for susceptibility to amoxicillin or reported resistant.
[1] Wild-type C. ulcerans is less susceptible to clindamycin.
[1] Wild-type C. ulcerans is less susceptible to clindamycin.
[A] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported "susceptible, increased exposure” (I) to cefotaxime. Isolates resistant to benzylpenicillin should be tested for susceptibility to cefotaxime or reported resistant.
[1] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported "susceptible, increased exposure” (I) to cefotaxime. Isolates resistant to benzylpenicillin should be tested for susceptibility to cefotaxime or reported resistant.
[1] Isolates susceptible to tetracycline can be reported susceptible to doxycycline. Isolates resistant to tetracycline should be tested for susceptibility to doxycycline or reported resistant.
[A] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported susceptible to meropenem. Isolates resistant to benzylpenicillin should be tested for susceptibility to meropenem or reported resistant.
[1] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported susceptible to meropenem. Isolates resistant to benzylpenicillin should be tested for susceptibility to meropenem or reported resistant.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported susceptible to amoxicillin. Isolates resistant to benzylpenicillin should be tested for susceptibility to amoxicillin or reported resistant.
[A] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported "susceptible, increased exposure” (I) to cefotaxime. Isolates resistant to benzylpenicillin should be tested for susceptibility to cefotaxime or reported resistant.
[1] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported "susceptible, increased exposure” (I) to cefotaxime. Isolates resistant to benzylpenicillin should be tested for susceptibility to cefotaxime or reported resistant.
[1] Isolates susceptible to tetracycline can be reported susceptible to doxycycline. Isolates resistant to tetracycline should be tested for susceptibility to doxycycline or reported resistant.
[A] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported susceptible to meropenem. Isolates resistant to benzylpenicillin should be tested for susceptibility to meropenem or reported resistant.
[1] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported susceptible to meropenem. Isolates resistant to benzylpenicillin should be tested for susceptibility to meropenem or reported resistant.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. Resistance to beta-lactam agents in C. acnes is rare. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. Resistance to beta-lactam agents in C. acnes is rare. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. Resistance to beta-lactam agents in C. acnes is rare. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. Resistance to beta-lactam agents in C. acnes is rare. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed.
[D] Examine zones carefully for colonies within zones. Colonies should be taken into account when reading.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. Resistance to beta-lactam agents in C. acnes is rare. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed. | [C] Susceptibility to ceftriaxone can be inferred from the cefotaxime disk diffusion test.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. Resistance to beta-lactam agents in C. acnes is rare. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed. | [3] Susceptibility to ceftriaxone can be inferred from the cefotaxime disk diffusion test.
[C] Susceptibility to ceftriaxone can be inferred from the cefotaxime disk diffusion test.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. Resistance to beta-lactam agents in C. acnes is rare. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. Resistance to beta-lactam agents in C. acnes is rare. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. Resistance to beta-lactam agents in C. acnes is rare. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. Resistance to beta-lactam agents in C. acnes is rare. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. Resistance to beta-lactam agents in C. acnes is rare. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. Resistance to beta-lactam agents in C. acnes is rare. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. Resistance to beta-lactam agents in C. acnes is rare. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. Resistance to beta-lactam agents in C. acnes is rare. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[D] Examine zones carefully for colonies within zones. Colonies should be taken into account when reading.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [C] Susceptibility to ceftriaxone can be inferred from the cefotaxime disk diffusion test.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [5] Susceptibility to ceftriaxone can be inferred from the cefotaxime disk diffusion test.
[C] Susceptibility to ceftriaxone can be inferred from the cefotaxime disk diffusion test.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [4] For susceptibility testing purposes, the concentration of  tazobactam is fixed at 4 mg/L.
[F] Ignore isolated colonies within the inhibition zone.
[6] Agar dilution is the reference method for mecillinam MIC determination.
[A] For other Enterobacterales, the activity of tigecycline varies from insufficient in Serratia spp., Proteus spp., Morganella morganii and Providencia spp. to variable in other species. For more information, see https://www.eucast.org/eucastguidancedocuments/. | [B] Zone diameter breakpoints validated for E. coli only. For C. koseri, use an MIC method.
[2] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [3] For other Enterobacterales, the activity of tigecycline varies from insufficient in Serratia spp., Proteus spp., Morganella morganii and Providencia spp. to variable in other species. For more information, see https://www.eucast.org/eucastguidancedocuments/.
[2] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[B] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [C] Examine zones carefully for colonies within zones. Colonies should be taken into account when reading.
[4] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[D] Metronidazole resistance is rare, but inadequate anaerobic conditions may lead to false resistance. In case of resistance, confirm sufficient anaerobicity, species identification and antimicrobial susceptibility test result.
[5] Metronidazole resistance is rare, but inadequate anaerobic conditions may lead to false resistance. In case of resistance, confirm sufficient anaerobicity, species identification and antimicrobial susceptibility test result.
[1] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L.
[3] For susceptibility testing purposes, the concentration of  tazobactam is fixed at 4 mg/L.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[C] Examine zones carefully for colonies within zones. Colonies should be taken into account when reading.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[D] Metronidazole resistance is rare, but inadequate anaerobic conditions may lead to false resistance. In case of resistance, confirm sufficient anaerobicity, species identification and antimicrobial susceptibility test result.
[5] Metronidazole resistance is rare, but inadequate anaerobic conditions may lead to false resistance. In case of resistance, confirm sufficient anaerobicity, species identification and antimicrobial susceptibility test result.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [4] For susceptibility testing purposes, the concentration of  tazobactam is fixed at 4 mg/L.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[C] Metronidazole resistance is rare, but inadequate anaerobic conditions may lead to false resistance. In case of resistance, confirm sufficient anaerobicity, species identification and antimicrobial susceptibility test result.
[5] Metronidazole resistance is rare, but inadequate anaerobic conditions may lead to false resistance. In case of resistance, confirm sufficient anaerobicity, species identification and antimicrobial susceptibility test result.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [4] For susceptibility testing purposes, the concentration of  tazobactam is fixed at 4 mg/L.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[C] Examine zones carefully for colonies within zones. Colonies should be taken into account when reading.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[D] Metronidazole resistance is rare, but inadequate anaerobic conditions may lead to false resistance. In case of resistance, confirm sufficient anaerobicity, species identification and antimicrobial susceptibility test result.
[5] Metronidazole resistance is rare, but inadequate anaerobic conditions may lead to false resistance. In case of resistance, confirm sufficient anaerobicity, species identification and antimicrobial susceptibility test result.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [4] For susceptibility testing purposes, the concentration of  tazobactam is fixed at 4 mg/L.
[2] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[B] Metronidazole resistance is rare, but inadequate anaerobic conditions may lead to false resistance. In case of resistance, confirm sufficient anaerobicity, species identification and antimicrobial susceptibility test result.
[3] Metronidazole resistance is rare, but inadequate anaerobic conditions may lead to false resistance. In case of resistance, confirm sufficient anaerobicity, species identification and antimicrobial susceptibility test result.
[1] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L.
[F] Ignore isolated colonies within the inhibition zone.
[6] Agar dilution is the reference method for mecillinam MIC determination.
[A] For E. faecalis that test resistant to ampicillin with disk diffusion, confirm with an MIC test.
[1] Susceptibility can be inferred from ampicillin.
[1] Susceptibility can be inferred from ampicillin.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[C]  | [C] Susceptibility to ciprofloxacin and levofloxacin can be inferred from the norfloxacin disk diffusion screening test. For moxifloxacin, see comment 1/B.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Vancomycin susceptible E. faecalis and E. faecium exhibit sharp zone edges and do not exhibit colonies in the inhibition zone. Examine zone edges with transmitted light (plate held up to light). If the zone edge is fuzzy, colonies grow within the zone  or if you are uncertain, then perform confirmatory testing with PCR or report resistant (see pictures below) even if the zone diameter is ≥ 12 mm. Isolates must not be reported susceptible before 24 h incubation.
[3] Isolates susceptible to ampicillin are without phenotypically detectable resistance mechanisms and the specified agents can be used in high exposure in combination therapy (see Note 4/D). Isolates resistant to ampicillin can be reported resistant. | [4] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[2] The addition of a beta-lactamase inhibitor does not add clinical benefit. Beta-lactamase producing enterococci are extremely rare.
[5] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L. | [2] The addition of a beta-lactamase inhibitor does not add clinical benefit. Beta-lactamase producing enterococci are extremely rare.
[A] Vancomycin susceptible E. faecalis and E. faecium exhibit sharp zone edges and do not exhibit colonies in the inhibition zone. Examine zone edges with transmitted light (plate held up to light). If the zone edge is fuzzy, colonies grow within the zone  or if you are uncertain, then perform confirmatory testing with PCR or report resistant (see pictures below) even if the zone diameter is ≥ 12 mm. Isolates must not be reported susceptible before 24 h incubation.
[A] Isolates susceptible to cefadroxil and/or cefalexin can be reported "susceptible, increased exposure” (I) to cefazolin.
[2] Isolates susceptible to cefadroxil and/or cefalexin can be reported "susceptible, increased exposure” (I) to cefazolin.
[D] Ignore isolated colonies within the inhibition zone (see pictures below).
[D] Ignore isolated colonies within the inhibition zone (see pictures below).
[4] Agar dilution is the reference method for fosfomycin. MICs must be determined in the presence of glucose-6-phosphate (25 mg/L in the medium). Follow the manufacturers' instructions for commercial systems.
[4] Agar dilution is the reference method for fosfomycin. MICs must be determined in the presence of glucose-6-phosphate (25 mg/L in the medium). Follow the manufacturers' instructions for commercial systems.
[F] Ignore isolated colonies within the inhibition zone.
[6] Agar dilution is the reference method for mecillinam MIC determination.
[F] Ignore isolated colonies within the inhibition zone.
[A] For other Enterobacterales, the activity of tigecycline varies from insufficient in Serratia spp., Proteus spp., Morganella morganii and Providencia spp. to variable in other species. For more information, see https://www.eucast.org/eucastguidancedocuments/. | [B] Zone diameter breakpoints validated for E. coli only. For C. koseri, use an MIC method.
[2] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [3] For other Enterobacterales, the activity of tigecycline varies from insufficient in Serratia spp., Proteus spp., Morganella morganii and Providencia spp. to variable in other species. For more information, see https://www.eucast.org/eucastguidancedocuments/.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L..
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[C] Examine zones carefully for colonies within zones. Colonies should be taken into account when reading. | [5] Inducible clindamycin resistance may occur. This can be detected by antagonism of clindamycin activity by a macrolide agent [erythromycin and clindamycin disks 12-16 mm apart (edge to edge)]. The clinical significance is unknown.
[5] Inducible clindamycin resistance may occur. This can be detected by antagonism of clindamycin activity by a macrolide agent [erythromycin and clindamycin disks 12-16 mm apart (edge to edge)]. The clinical significance is unknown.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[D] Metronidazole resistance is rare, but inadequate anaerobic conditions may lead to false resistance. In case of resistance, confirm sufficient anaerobicity, species identification and antimicrobial susceptibility test result.
[6] Metronidazole resistance is rare, but inadequate anaerobic conditions may lead to false resistance. In case of resistance, confirm sufficient anaerobicity, species identification and antimicrobial susceptibility test result.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [4] For susceptibility testing purposes, the concentration of  tazobactam is fixed at 4 mg/L.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[C] Examine zones carefully for colonies within zones. Colonies should be taken into account when reading.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[D] Metronidazole resistance is rare, but inadequate anaerobic conditions may lead to false resistance. In case of resistance, confirm sufficient anaerobicity, species identification and antimicrobial susceptibility test result.
[6] Metronidazole resistance is rare, but inadequate anaerobic conditions may lead to false resistance. In case of resistance, confirm sufficient anaerobicity, species identification and antimicrobial susceptibility test result.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[C] Examine zones carefully for colonies within zones. Colonies should be taken into account when reading.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[D] Metronidazole resistance is rare, but inadequate anaerobic conditions may lead to false resistance. In case of resistance, confirm sufficient anaerobicity, species identification and antimicrobial susceptibility test result.
[6] Metronidazole resistance is rare, but inadequate anaerobic conditions may lead to false resistance. In case of resistance, confirm sufficient anaerobicity, species identification and antimicrobial susceptibility test result.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [5] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[6] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[6] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below. | [2] Beta-lactamase positive isolates can be reported resistant to ampicillin, amoxicillin and piperacillin without inhibitors. Tests based on a chromogenic cephalosporin can be used to detect the beta-lactamase.
[2] Beta-lactamase positive isolates can be reported resistant to ampicillin, amoxicillin and piperacillin without inhibitors. Tests based on a chromogenic cephalosporin can be used to detect the beta-lactamase.
[2] Beta-lactamase positive isolates can be reported resistant to ampicillin, amoxicillin and piperacillin without inhibitors. Tests based on a chromogenic cephalosporin can be used to detect the beta-lactamase.
[2] Beta-lactamase positive isolates can be reported resistant to ampicillin, amoxicillin and piperacillin without inhibitors. Tests based on a chromogenic cephalosporin can be used to detect the beta-lactamase.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[1] For chloramphenicol treatment in meningitis, see table of dosages.
[1] For chloramphenicol treatment in meningitis, see table of dosages.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below. | [3] See table of dosages for dosing for different indications.
[3] See table of dosages for dosing for different indications.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all carbapenems for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all carbapenems for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all carbapenems for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all carbapenems for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[B]  | [B] Isolates categorised as screen negative can be reported susceptible to ciprofloxacin, levofloxacin, moxifloxacin and ofloxacin. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for Gram-positive organisms and nalidixic acid for H. influenzae and M. catarrhalis).
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[1/A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[4] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L. | [5] Susceptibility can be inferred from amoxicillin-clavulanic acid iv.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[7] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[2] Susceptibility can be inferred from benzylpenicillin susceptibility.
[2] Susceptibility can be inferred from benzylpenicillin susceptibility.
[1] Susceptibility can be inferred from erythromycin susceptibility.
[1] Susceptibility can be inferred from erythromycin susceptibility.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline. Isolates categorised as resistant should be tested for susceptibility to doxycycline or reported resistant.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Isolates susceptible to cefadroxil and/or cefalexin can be reported "susceptible, increased exposure” (I) to cefazolin.
[2] Isolates susceptible to cefadroxil and/or cefalexin can be reported "susceptible, increased exposure” (I) to cefazolin.
[F] Ignore isolated colonies within the inhibition zone.
[6] Agar dilution is the reference method for mecillinam MIC determination.
[F] Ignore isolated colonies within the inhibition zone.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[1] Erythromycin can be used to screen for macrolide resistance in Moraxella catarrhalis. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[1] Erythromycin can be used to screen for macrolide resistance in Moraxella catarrhalis. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[A] Erythromycin can be used to screen for macrolide resistance in Moraxella catarrhalis. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[B]  | [B] Isolates categorised as screen negative can be reported susceptible to ciprofloxacin, levofloxacin, moxifloxacin and ofloxacin. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for Gram-positive organisms and nalidixic acid for H. influenzae and M. catarrhalis).
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[1] Erythromycin can be used to screen for macrolide resistance in Moraxella catarrhalis. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L. | [3] Susceptibility can be inferred from amoxicillin-clavulanic acid.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[1] For bedaquiline, breakpoints were determined using the EUCAST reference method.
[2] For delamanid and pretomanid, breakpoints were not determined with the EUCAST reference method. Therefore they are provisional and might change according to the results of future studies with the EUCAST reference method for MIC determination.
3.The provisional breakpoint was determined according to MIC data determined with the agar dilution and the agar proportion methods.
[1] Always test for beta-lactamase (tests based on a chromogenic cephalosporin can be used). If beta-lactamase positive, report resistant to ampicillin and amoxicillin. If beta-lactamase negative, determine the MIC of benzylpenicillin. Infer the susceptibility to ampicillin and amoxicillin from the benzylpenicillin MIC (do not report benzylpenicillin susceptibility).
[1] For chloramphenicol treatment in meningitis, see table of dosages.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory. | [2] Breakpoints for serious N. meningitidis systemic infections (meningitis with or without septicemia) have been determined for meropenem only.
[1] Tetracycline can be used to predict susceptibility to minocycline for prophylaxis against N. meningitidis infections.
[1] Tetracycline can be used to predict susceptibility to minocycline for prophylaxis against N. meningitidis infections.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[C] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [D] Examine zones carefully for colonies within zones. Colonies should be taken into account when reading. | [3] Inducible clindamycin resistance may occur. This can be detected by antagonism of clindamycin activity by a macrolide agent [erythromycin and clindamycin disks 12-16 mm apart (edge to edge)]. The clinical significance is unknown.
[4] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [3] Inducible clindamycin resistance may occur. This can be detected by antagonism of clindamycin activity by a macrolide agent [erythromycin and clindamycin disks 12-16 mm apart (edge to edge)]. The clinical significance is unknown.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[E] Metronidazole resistance is rare, but inadequate anaerobic conditions may lead to false resistance. In case of resistance, confirm sufficient anaerobicity, species identification and antimicrobial susceptibility test result.
[5] Metronidazole resistance is rare, but inadequate anaerobic conditions may lead to false resistance. In case of resistance, confirm sufficient anaerobicity, species identification and antimicrobial susceptibility test result.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L..
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[C] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [D] Examine zones carefully for colonies within zones. Colonies should be taken into account when reading. | [5] Inducible clindamycin resistance may occur. This can be detected by antagonism of clindamycin activity by a macrolide agent [erythromycin and clindamycin disks 12-16 mm apart (edge to edge)]. The clinical significance is unknown.
[6] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [5] Inducible clindamycin resistance may occur. This can be detected by antagonism of clindamycin activity by a macrolide agent [erythromycin and clindamycin disks 12-16 mm apart (edge to edge)]. The clinical significance is unknown.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[E] Metronidazole resistance is rare, but inadequate anaerobic conditions may lead to false resistance. In case of resistance, confirm sufficient anaerobicity, species identification and antimicrobial susceptibility test result.
[7] Metronidazole resistance is rare, but inadequate anaerobic conditions may lead to false resistance. In case of resistance, confirm sufficient anaerobicity, species identification and antimicrobial susceptibility test result.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [4] For susceptibility testing purposes, the concentration of  tazobactam is fixed at 4 mg/L.
[F] Ignore isolated colonies within the inhibition zone.
[6] Agar dilution is the reference method for mecillinam MIC determination.
[F] Ignore isolated colonies within the inhibition zone.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[C] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [D] Examine zones carefully for colonies within zones. Colonies should be taken into account when reading. | [3] Inducible clindamycin resistance may occur. This can be detected by antagonism of clindamycin activity by a macrolide agent [erythromycin and clindamycin disks 12-16 mm apart (edge to edge)]. The clinical significance is unknown.
[4] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [3] Inducible clindamycin resistance may occur. This can be detected by antagonism of clindamycin activity by a macrolide agent [erythromycin and clindamycin disks 12-16 mm apart (edge to edge)]. The clinical significance is unknown.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[E] Metronidazole resistance is rare, but inadequate anaerobic conditions may lead to false resistance. In case of resistance, confirm sufficient anaerobicity, species identification and antimicrobial susceptibility test result.
[5] Metronidazole resistance is rare, but inadequate anaerobic conditions may lead to false resistance. In case of resistance, confirm sufficient anaerobicity, species identification and antimicrobial susceptibility test result.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[C] Examine zones carefully for colonies within zones. Colonies should be taken into account when reading.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[D] Metronidazole resistance is rare, but inadequate anaerobic conditions may lead to false resistance. In case of resistance, confirm sufficient anaerobicity, species identification and antimicrobial susceptibility test result.
[3] Metronidazole resistance is rare, but inadequate anaerobic conditions may lead to false resistance. In case of resistance, confirm sufficient anaerobicity, species identification and antimicrobial susceptibility test result.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[2] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [1] Colistin MIC determination should be performed with broth microdilution. Quality control must be performed with both a susceptible QC strain (E. coli ATCC 25922 or P. aeruginosa ATCC 27853) and the colistin resistant E. coli NCTC 13846 (mcr-1 positive).
[2] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[3] For susceptibility testing purposes, the concentration of avibactam is fixed at 4 mg/L.
[4] See table of dosages for dosing for different indications.
[5] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L. | [4] See table of dosages for dosing for different indications.
[2] Broth microdilution MIC determination must be performed in iron-depleted Mueller-Hinton broth and specific reading instructions must be followed. For testing conditions and reading instructions, see https://www.eucast.org/eucastguidancedocuments/.
[1] For susceptibility testing purposes, the concentration of relebactam is fixed at 4 mg/L.
[2] For susceptibility testing purposes, the concentration of vaborbactam is fixed at 8 mg/L.
[1] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note B.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note B.
[B] Isolates categorised as screen negative can be reported susceptible to ciprofloxacin and levofloxacin. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Susceptibility to doxycycline can be inferred from the tetracycline disk diffusion screening test.
[8] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[8] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] There is clinical evidence for ciprofloxacin to indicate a poor response in systemic infections caused by Salmonella spp. with any detectable fluoroquinolone resistance mechanisms. The available data relate mainly to Salmonella Typhi but there are also case reports of poor response with other Salmonella species.
[A] There may be growth within the inhibition zone. The density of growth may vary from a fine haze to substantial growth (see pictures below). If any zone edge can be seen, ignore growth within the inhibition zone and read the zone diameter. | [1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Erythromycin can be used to screen for macrolide resistance in staphylococci. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[B] Place the erythromycin and clindamycin disks 12-20 mm apart (edge to edge) and look for antagonism (the D phenomenon) to detect inducible clindamycin resistance. | [2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant and consider adding this comment to the report: "Clindamycin may still be used for short-term therapy of less serious skin and soft tissue infections as constitutive resistance is unlikely to develop during such therapy".
[2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant and consider adding this comment to the report: "Clindamycin may still be used for short-term therapy of less serious skin and soft tissue infections as constitutive resistance is unlikely to develop during such therapy".
[1] Erythromycin can be used to screen for macrolide resistance in staphylococci. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[3] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturers' instructions for commercial systems.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[A] Erythromycin can be used to screen for macrolide resistance in staphylococci. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Erythromycin can be used to screen for macrolide resistance in staphylococci. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[D]  | [D] Isolates categorised as screen negative can be reported susceptible to moxifloxacin and "susceptible increased exposure" (I) to levofloxacin. For ciprofloxacin, the isolate is without phenotypically detectable resistance mechanisms and can be used in high exposure in combination therapy (see Note 2/A). Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Erythromycin can be used to screen for macrolide resistance in staphylococci. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[5] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[5] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[2] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[3] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [2] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Isolates susceptible to linezolid can be reported susceptible to tedizolid.
[1] Isolates susceptible to linezolid can be reported susceptible to tedizolid.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[F] Methicillin-susceptible isolates can be reported susceptible to ceftobiprole without further testing.
[9] Methicillin-susceptible isolates can be reported susceptible to ceftobiprole without further testing.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [B] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[2] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[D] Methicillin-susceptible isolates can be reported susceptible to ceftaroline without further testing.
[D] Methicillin-susceptible isolates can be reported susceptible to ceftaroline without further testing.
[7] Methicillin-susceptible isolates can be reported susceptible to ceftaroline without further testing.
[7] Methicillin-susceptible isolates can be reported susceptible to ceftaroline without further testing.
[2] Daptomycin MICs must be determined in the presence of Ca (50 mg/L in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturers' instructions for commercial systems. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[B] For MRSA that test susceptible with disk diffusion, the results should be confirmed with an MIC test.
[A] Susceptibility of staphylococci to cephalosporins is inferred from the cefoxitin susceptibility except for cefixime, ceftazidime, ceftazidime-avibactam, ceftibuten, cefiderocol and ceftolozane-tazobactam, which do not have breakpoints and should not be used for staphylococcal infections. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. If cefazolin, cefepime, cefotaxime, ceftriaxone or cefuroxime iv are reported for methicillin-susceptible staphylococci, these should be reported “susceptible, increased exposure” (I) - see https://www.eucast.org/eucastguidancedocuments/. Many methicillin-resistant S. aureus are susceptible to ceftaroline and ceftobiprole, see Notes 7/D and 9/F. | [B] If coagulase-negative staphylococci are not identified to species level, use zone diameter breakpoints S≥25, R<25 mm, with an ATU of 22-24 mm. For isolates with results inside the ATU: identify species, perform PCR for mecA/mecC or report resistant.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[B] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[B] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note | [3] Ofloxacin breakpoints for Staphylococcus spp. have been removed since in systemic infections with staphylococci the agent is inferior to other fluoroquinolones. For topical use of ofloxacin, see tables of topical agents.
[3] Ofloxacin breakpoints for Staphylococcus spp. have been removed since in systemic infections with staphylococci the agent is inferior to other fluoroquinolones. For topical use of ofloxacin, see tables of topical agents.
[2] Breakpoints for nasal decolonization in carriers of S. aureus, S ≤1, R >1 mg/L (disk diffusion with mupirocin 200 µg disk S ≥30, R <30 mm). For short term suppression of nasal colonization (usually as a perioperative practice) breakpoints of S ≤256, R >256 mg/L (disk diffusion S ≥18 mm, R <18 mm) can be used.
[2] Breakpoints for nasal decolonization in carriers of S. aureus, S ≤1, R >1 mg/L (disk diffusion with mupirocin 200 µg disk S ≥30, R <30 mm). For short term suppression of nasal colonization (usually as a perioperative practice) breakpoints of S ≤256, R >256 mg/L (disk diffusion S ≥18 mm, R <18 mm) can be used.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for Gram-positive organisms and nalidixic acid for H. influenzae and M. catarrhalis).
[3] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturers' instructions for commercial systems.
[A] Most S. aureus are penicillinase producers and some are methicillin resistant. Either mechanism renders them resistant to benzylpenicillin, phenoxymethylpenicillin, ampicillin, amoxicillin, piperacillin and ticarcillin. Isolates that test susceptible to benzylpenicillin and cefoxitin can be reported susceptible to all penicillins. Isolatesthat test resistant to benzylpenicillin but susceptible to cefoxitin are susceptible to β-lactam β-lactamase inhibitor combinations, the isoxazolylpenicillins (oxacillin, cloxacillin, dicloxacillin and flucloxacillin) and nafcillin. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. Isolates that test resistant to cefoxitin are resistant to all penicillins. | [B] For S. aureus, disk diffusion is more reliable than MIC determination for detection of penicillinase producers, provided the zone diameter is measured AND the zone edge for isolates with zone diameters ≥26 mm is closely inspected (see pictures below). Examine the zone edge with transmitted light (plate held up to light). If the zone diameter is <26 mm, then report resistant. If the zone diameter is ≥26 mm AND the zone edge is sharp (no reduction of growth towards zone edge, like a "cliff"), then report resistant. If not sharp (reduction of growth towards zone edge,  like a "beach"), then report susceptible and if uncertain, then report resistant. Chromogenic cephalosporin-based beta-lactamase tests do not reliably detect staphylococcal penicillinase.
[1] Most S. aureus are penicillinase producers and some are methicillin resistant. Either mechanism renders them resistant to benzylpenicillin, phenoxymethylpenicillin, ampicillin, amoxicillin, piperacillin and ticarcillin. Isolates that test susceptible to benzylpenicillin and cefoxitin can be reported susceptible to all penicillins. Isolatesthat test resistant to benzylpenicillin but susceptible to cefoxitin are susceptible to β-lactam β-lactamase inhibitor combinations, the isoxazolylpenicillins (oxacillin, cloxacillin, dicloxacillin and flucloxacillin) and nafcillin. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. Isolates that test resistant to cefoxitin are resistant to all penicillins.
[3] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturers' instructions for commercial systems.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[E] For screening for methicillin resistance in S. pseudintermedius, S. intermedius, S. schleiferi and S. coagulans.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [B] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[2] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] Susceptibility of staphylococci to cephalosporins is inferred from the cefoxitin susceptibility except for cefixime, ceftazidime, ceftazidime-avibactam, ceftibuten, cefiderocol and ceftolozane-tazobactam, which do not have breakpoints and should not be used for staphylococcal infections. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. If cefazolin, cefepime, cefotaxime, ceftriaxone or cefuroxime iv are reported for methicillin-susceptible staphylococci, these should be reported “susceptible, increased exposure” (I) - see https://www.eucast.org/eucastguidancedocuments/. Many methicillin-resistant S. aureus are susceptible to ceftaroline and ceftobiprole, see Notes 7/D and 9/F. | [B] If coagulase-negative staphylococci are not identified to species level, use zone diameter breakpoints S≥25, R<25 mm, with an ATU of 22-24 mm. For isolates with results inside the ATU: identify species, perform PCR for mecA/mecC or report resistant.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[B] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[B] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note | [3] Ofloxacin breakpoints for Staphylococcus spp. have been removed since in systemic infections with staphylococci the agent is inferior to other fluoroquinolones. For topical use of ofloxacin, see tables of topical agents.
[3] Ofloxacin breakpoints for Staphylococcus spp. have been removed since in systemic infections with staphylococci the agent is inferior to other fluoroquinolones. For topical use of ofloxacin, see tables of topical agents.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] Susceptibility of staphylococci to cephalosporins is inferred from the cefoxitin susceptibility except for cefixime, ceftazidime, ceftazidime-avibactam, ceftibuten, cefiderocol and ceftolozane-tazobactam, which do not have breakpoints and should not be used for staphylococcal infections. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. If cefazolin, cefepime, cefotaxime, ceftriaxone or cefuroxime iv are reported for methicillin-susceptible staphylococci, these should be reported “susceptible, increased exposure” (I) - see https://www.eucast.org/eucastguidancedocuments/. Many methicillin-resistant S. aureus are susceptible to ceftaroline and ceftobiprole, see Notes 7/D and 9/F. | [B] If coagulase-negative staphylococci are not identified to species level, use zone diameter breakpoints S≥25, R<25 mm, with an ATU of 22-24 mm. For isolates with results inside the ATU: identify species, perform PCR for mecA/mecC or report resistant.
[E] For screening for methicillin resistance in S. pseudintermedius, S. intermedius, S. schleiferi and S. coagulans.
[A] Susceptibility of staphylococci to cephalosporins is inferred from the cefoxitin susceptibility except for cefixime, ceftazidime, ceftazidime-avibactam, ceftibuten, cefiderocol and ceftolozane-tazobactam, which do not have breakpoints and should not be used for staphylococcal infections. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. If cefazolin, cefepime, cefotaxime, ceftriaxone or cefuroxime iv are reported for methicillin-susceptible staphylococci, these should be reported “susceptible, increased exposure” (I) - see https://www.eucast.org/eucastguidancedocuments/. Many methicillin-resistant S. aureus are susceptible to ceftaroline and ceftobiprole, see Notes 7/D and 9/F. | [B] If coagulase-negative staphylococci are not identified to species level, use zone diameter breakpoints S≥25, R<25 mm, with an ATU of 22-24 mm. For isolates with results inside the ATU: identify species, perform PCR for mecA/mecC or report resistant.
[E] For screening for methicillin resistance in S. pseudintermedius, S. intermedius, S. schleiferi and S. coagulans.
[E] For screening for methicillin resistance in S. pseudintermedius, S. intermedius, S. schleiferi and S. coagulans.
[C] Most staphylococci are penicillinase producers and some are methicillin resistant. Either mechanism renders them resistant to benzylpenicillin, phenoxymethylpenicillin, ampicillin, amoxicillin, piperacillin and ticarcillin. No currently available method can reliably detect penicillinase production in all species of staphylococci but methicillin resistance can be detected with cefoxitin as described. | [D] Ampicillin susceptible S. saprophyticus are mecA-negative and susceptible to ampicillin, amoxicillin and piperacillin (without or with a beta-lactamase inhibitor).
[1] Erythromycin can be used to screen for macrolide resistance in Streptococcus groups A, B, C and
[B] Place the erythromycin and clindamycin disks 12-16 mm apart (edge to edge) and look for antagonism (the D phenomenon) to detect inducible clindamycin resistance. | [2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant and consider adding this comment to the report: "Clindamycin may still be used for short-term therapy of less serious skin and soft tissue infections as constitutive resistance is unlikely to develop during such therapy". The clinical importance of inducible clindamycin resistance in combination treatment of severe S. pyogenes infections is not known.
[2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant and consider adding this comment to the report: "Clindamycin may still be used for short-term therapy of less serious skin and soft tissue infections as constitutive resistance is unlikely to develop during such therapy". The clinical importance of inducible clindamycin resistance in combination treatment of severe S. pyogenes infections is not known.
[1] Erythromycin can be used to screen for macrolide resistance in Streptococcus groups A, B, C and
[2] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturers' instructions for commercial systems. | [3] Isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] Daptomycin MICs must be determined in the presence of Ca (50 mg/L in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturers' instructions for commercial systems. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[A] Erythromycin can be used to screen for macrolide resistance in Streptococcus groups A, B, C and
[1] Erythromycin can be used to screen for macrolide resistance in Streptococcus groups A, B, C and
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[B] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[B] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[C]  | [C] Isolates categorised as screen negative can be reported susceptible to moxifloxacin and as "susceptible increased exposure" (I) to levofloxacin. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for Gram-positive organisms and nalidixic acid for H. influenzae and M. catarrhalis).
[2] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturers' instructions for commercial systems. | [3] Isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Erythromycin can be used to screen for macrolide resistance in Streptococcus groups A, B, C and
[4] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[4] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[B] Non-wild type isolates were not available when developing the disk diffusion method. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[3] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [2] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Isolates susceptible to linezolid can be reported susceptible to tedizolid. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] Isolates susceptible to linezolid can be reported susceptible to tedizolid. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[B] Non-wild type isolates were not available when developing the disk diffusion method. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturers' instructions for commercial systems. | [3] Isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturers' instructions for commercial systems. | [3] Isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L. | [2] The addition of a beta-lactamase inhibitor does not add clinical benefit.
[1] Erythromycin can be used to screen for macrolide resistance in Streptococcus pneumoniae. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[B] Place the erythromycin and clindamycin disks 12-16 mm apart (edge to edge) and look for antagonism (the D phenomenon) to detect inducible clindamycin resistance. | [2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant.
[2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant.
[1] Erythromycin can be used to screen for macrolide resistance in Streptococcus pneumoniae. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[A] Erythromycin can be used to screen for macrolide resistance in Streptococcus pneumoniae. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Erythromycin can be used to screen for macrolide resistance in Streptococcus pneumoniae. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[B]  | [B] Isolates categorised as screen negative can be reported susceptible to moxifloxacin and as "susceptible increased exposure" (I) to levofloxacin. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for Gram-positive organisms and nalidixic acid for H. influenzae and M. catarrhalis).
[D] For interpretation of the oxacillin disk screen, see flow chart below. | [1] The oxacillin 1 µg disk diffusion screening test or a benzylpenicillin MIC test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (oxacillin zone diameter ≥20 mm, or benzylpenicillin MIC ≤0.06 mg/L) all beta-lactam agents for which clinical breakpoints are available, including those with “Note” can be reported susceptible without further testing, except for cefaclor, which if reported, should be reported as “susceptible, increased exposure” (I). When the screen is positive (zone diameter <20 mm, or benzylpenicillin MIC >0.06 mg/L), see flow chart below.
[1] Erythromycin can be used to screen for macrolide resistance in Streptococcus pneumoniae. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[A] Non-wild typeisolates were not available when developing the disk diffusion method. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Non-wild typeisolates were not available when developing the disk diffusion method. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Place the erythromycin and clindamycin disks 12-16 mm apart (edge to edge) and look for antagonism (the D phenomenon) to detect inducible clindamycin resistance. | [1] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant.
[1] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant.
[A] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. See Note 1/A on penicillins.
[A] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. See Note 1/A on penicillins.
[A] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. See Note 1/A on penicillins.
[A] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. See Note 1/A on penicillins.
[1] For susceptibility testing purposes, the concentration of relebactam is fixed at 4 mg/L. | [2] The addition of a beta-lactamase inhibitor does not add clinical benefit.
[A] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. Isolates categorised as screen negative can be reported susceptible to beta-lactam agents for which clinical breakpoints are listed (including those with “Note”). Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[B] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. Isolates categorised as screen negative can be reported susceptible to beta-lactam agents for which clinical breakpoints are listed (including those with “Note”). Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[2] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[B] Non-wild type isolates were not available when developing the disk diffusion method. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[B] Non-wild type isolates were not available when developing the disk diffusion method. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Susceptibility to azithromycin (and erythromycin when azithromycin is not available) is inferred from the erythromycin disk diffusion test.
[A] Susceptibility to ciprofloxacin and levofloxacin can be inferred from the pefloxacin disk diffusion screening test.
[1/A] Susceptibility to azithromycin (and erythromycin when azithromycin is not available) is inferred from the erythromycin disk diffusion test.
[A] Susceptibility to ciprofloxacin and levofloxacin can be inferred from the pefloxacin disk diffusion screening test.
[A] Susceptibility to ciprofloxacin and levofloxacin can be inferred from the pefloxacin disk diffusion screening test.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1/A] Susceptibility to doxycycline (and tetracycline when doxycycline is not available) is inferred from the tetracycline disk diffusion test.
[1] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[2] The intrinsically low activity of imipenem against Morganella morganii, Proteus spp. and Providencia spp. requires the high exposure of imipenem.
[2] The intrinsically low activity of imipenem against Morganella morganii, Proteus spp. and Providencia spp. requires the high exposure of imipenem.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [D] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[3] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[3] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[1] The aztreonam breakpoints for Enterobacterales will detect clinically important resistance mechanisms (including ESBL). Some isolates that produce beta-lactamases are susceptible to aztreonam with these breakpoints and should be reported as tested, i.e. the presence or absence of an ESBL does not in itself influence the categorisation of susceptibility. ESBL detection and characterisation are recommended for public health and infection control purposes.
[1] The aztreonam breakpoints for Enterobacterales will detect clinically important resistance mechanisms (including ESBL). Some isolates that produce beta-lactamases are susceptible to aztreonam with these breakpoints and should be reported as tested, i.e. the presence or absence of an ESBL does not in itself influence the categorisation of susceptibility. ESBL detection and characterisation are recommended for public health and infection control purposes.
[2] For susceptibility testing purposes, the concentration of avibactam is fixed at 4 mg/L.
[2] In meningitis, where all fluoroquinolone resistance mechanisms must be excluded, either perform an MIC test, or infer susceptibility from the pefloxacin 5 µg screening test.
[3] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [2] Colistin MIC determination should be performed with broth microdilution. Quality control must be performed with both a susceptible QC strain (E. coli ATCC 25922 or P. aeruginosa ATCC 27853) and the colistin resistant E. coli NCTC 13846 (mcr-1 positive).
[6] For susceptibility testing purposes, the concentration of avibactam is fixed at 4 mg/L.
[7] See table of dosages for dosing for different indications.
[8] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L. | [7] See table of dosages for dosing for different indications.
[4] Broth microdilution MIC determination must be performed in iron-depleted Mueller-Hinton broth and specific reading instructions must be followed. For testing conditions and reading instructions, see https://www.eucast.org/eucastguidancedocuments/.
[5] The cefoxitin cut-off value (8 mg/L) has a high sensitivity but poor specificity for identification of AmpC-producing Enterobacterales as this agent is also affected by permeability alterations and some carbapenemases. Classical non-AmpC producers are wild type, whereas plasmid AmpC producers or chromosomal AmpC hyperproducers are non-wild type.
[3] For susceptibility testing purposes, the concentration of enmetazobactam is fixed at 8 mg/L.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[3] For susceptibility testing purposes, the concentration of relebactam is fixed at 4 mg/L.
[4] For susceptibility testing purposes, the concentration of vaborbactam is fixed at 8 mg/L.
[3] Fluoroquinolone breakpoints are available for other agents.
[3] Fluoroquinolone breakpoints are available for other agents.
[A] Tests with a ciprofloxacin 5 µg disk will not reliably exclude all fluoroquinolone resistance mechanisms in Salmonella spp. Perform an MIC test, or infer susceptibility from the pefloxacin 5 µg screening test. | [B] In meningitis, where all fluoroquinolone resistance mechanisms must be excluded, either perform an MIC test, or infer susceptibility from the pefloxacin 5 µg screening test. | [C] The pefloxacin screening test can also be used to detect fluoroquinolone resistance mechanisms in other Enterobacterales such as E. coli, K. pneumoniae and Shigella spp.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for Gram-positive organisms and nalidixic acid for H. influenzae and M. catarrhalis).
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[8] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[8] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[5] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[3] For isolates with confirmed MIC 2 mg/L (one dilution above the breakpoint), itraconazole may be considered for treatment of chronic pulmonary aspergillosis when no alternative is available and when  sufficient exposure (>2 mg/L) is ensured via TDM.
[3] For isolates with confirmed MIC 2 mg/L (one dilution above the breakpoint), itraconazole may be considered for treatment of chronic pulmonary aspergillosis when no alternative is available and when  sufficient exposure (>2 mg/L) is ensured via TDM.
[6] For isolates with confirmed MIC 2 mg/L (one dilution above the breakpoint), voriconazole may be considered for treatment of chronic pulmonary aspergillosis when no alternative is available and when sufficient exposure (>2-3 mg/L) is ensured via TDM.
[3] For isolates with confirmed MIC 2 mg/L (one dilution above the breakpoint), itraconazole may be considered for treatment of chronic pulmonary aspergillosis when no alternative is available and when  sufficient exposure (>2 mg/L) is ensured via TDM.
[6] For isolates with confirmed MIC 2 mg/L (one dilution above the breakpoint), voriconazole may be considered for treatment of chronic pulmonary aspergillosis when no alternative is available and when sufficient exposure (>2-3 mg/L) is ensured via TDM.
[3] For isolates with confirmed MIC 2 mg/L (one dilution above the breakpoint), itraconazole may be considered for treatment of chronic pulmonary aspergillosis when no alternative is available and when  sufficient exposure (>2 mg/L) is ensured via TDM.
[7] Breakpoints apply for MICs determined with Tween 20 supplemented medium according to the EUCAST E.Def 7.4 method.
[8] Strains with MIC values above the S/I breakpoint are rare or not yet reported. The identification and antifungal susceptibility tests on any such isolate must be repeated and if the result is confirmed the isolate sent to a reference laboratory. Until there is evidence regarding clinical response for confirmed isolates with MIC above the current resistant breakpoint they should be reported resistant. A clinical response of 76% was achieved in infections caused by the species listed below when MICs were lower than or equal to the epidemiological cut-offs. Therefore, wild type populations of C. albicans, C. dubliniensis, C. parapsilosis and C. tropicalis are considered susceptible.
[7] Breakpoints apply for MICs determined with Tween 20 supplemented medium according to the EUCAST E.Def 7.4 method.
[8] Strains with MIC values above the S/I breakpoint are rare or not yet reported. The identification and antifungal susceptibility tests on any such isolate must be repeated and if the result is confirmed the isolate sent to a reference laboratory. Until there is evidence regarding clinical response for confirmed isolates with MIC above the current resistant breakpoint they should be reported resistant. A clinical response of 76% was achieved in infections caused by the species listed below when MICs were lower than or equal to the epidemiological cut-offs. Therefore, wild type populations of C. albicans, C. dubliniensis, C. parapsilosis and C. tropicalis are considered susceptible.
[7] Breakpoints apply for MICs determined with Tween 20 supplemented medium according to the EUCAST E.Def 7.4 method.
[7] Breakpoints apply for MICs determined with Tween 20 supplemented medium according to the EUCAST E.Def 7.4 method.
[8] Strains with MIC values above the S/I breakpoint are rare or not yet reported. The identification and antifungal susceptibility tests on any such isolate must be repeated and if the result is confirmed the isolate sent to a reference laboratory. Until there is evidence regarding clinical response for confirmed isolates with MIC above the current resistant breakpoint they should be reported resistant. A clinical response of 76% was achieved in infections caused by the species listed below when MICs were lower than or equal to the epidemiological cut-offs. Therefore, wild type populations of C. albicans, C. dubliniensis, C. parapsilosis and C. tropicalis are considered susceptible.
[1] The entire C. auris wild-type population is in the I category. The Susceptible category (≤0.001 mg/L) is simply to avoid missclassification of any WT strains as "S" strains.
[4] The entire C. glabrata wild-type population is in the I category. MICs against C. glabrata should be interpreted as resistant when above 16 mg/L. Susceptible category (≤0.001 mg/L) is simply to avoid missclassification of any wild-typestrains as "S" strains.
[7] Breakpoints apply for MICs determined with Tween 20 supplemented medium according to the EUCAST E.Def 7.4 method.
[7] Breakpoints apply for MICs determined with Tween 20 supplemented medium according to the EUCAST E.Def 7.4 method.
[A] There may be growth within the inhibition zone. The density of growth may vary from a fine haze to substantial growth (see pictures below). If any zone edge can be seen, ignore growth within the inhibition zone and read the zone diameter. | [1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[2] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [1] Colistin MIC determination should be performed with broth microdilution. Quality control must be performed with both a susceptible QC strain (E. coli ATCC 25922 or P. aeruginosa ATCC 27853) and the colistin resistant E. coli NCTC 13846 (mcr-1 positive).
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[4] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[4] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] Susceptibility can be inferred from the norfloxacin disk diffusion screening test. See Note
[1] Susceptibility can be inferred from ciprofloxacin susceptibility.
[C]  | [C] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance.
[A] Non-wild type isolates were not available when developing the disk diffusion method.
[A] Susceptibility can be inferred from the norfloxacin disk diffusion screening test. See Note
[1] Susceptibility can be inferred from ciprofloxacin susceptibility.
[C]  | [C] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance.
[A] Non-wild type isolates were not available when developing the disk diffusion method.
[A] Read the obvious zone edge and disregard haze or growth within the inhibition zone (see pictures below). | [1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[B]  | [B] Isolates categorised as screen negative can be reported "susceptible increased exposure" (I) to ciprofloxacin and levofloxacin. Isolates categorised as screen positive can be reported resistant to ciprofloxacin and levofloxacin.
[A] Non-wild type isolates were not available when developing the disk diffusion method.
[1] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported susceptible to amoxicillin. Isolates resistant to benzylpenicillin should be tested for susceptibility to amoxicillin or reported resistant.
[1] Isolates susceptible to tetracycline can be reported susceptible to doxycycline. Isolates resistant to tetracycline should be tested for susceptibility to doxycycline or reported resistant.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[2] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [B] Examine zones carefully for colonies within zones. Colonies should be taken into account when reading.
[5] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[5] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L.
[3] Isolates susceptible to ampicillin-sulbactam and amoxicillin-clavulanic acid may be resistant to piperacillin-tazobactam.
[4] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L. | [3] Isolates susceptible to ampicillin-sulbactam and amoxicillin-clavulanic acid may be resistant to piperacillin-tazobactam.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] Isolates susceptible to tetracycline can be reported susceptible to doxycycline. Isolates resistant to tetracycline should be tested for susceptibility to doxycycline or reported resistant.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [B] Examine zones carefully for colonies close to the zone edge. Colonies should be taken into account when reading.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[C] Read the obvious zone edges and disregard haze or faint growth within the inhibition zone. | [2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] There may be growth within the inhibition zone. The density of growth may vary from a fine haze to substantial growth (see pictures below). If any zone edge can be seen, ignore growth within the inhibition zone and read the zone diameter. | [1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Isolates categorised as screen negative can be reported "susceptible increased exposure" (I) to doxycyline. Isolates categorised as screen positive can be reported resistant to doxycycline.
[A] Susceptibility to azithromycin and clarithromycin can be inferred from erythromycin.
[1] Susceptibility to azithromycin and clarithromycin can be inferred from erythromycin.
[A] Susceptibility to doxycycline can be inferred from tetracycline.
[1] Susceptibility to doxycycline can be inferred from tetracycline.
[A] Susceptibility to azithromycin and clarithromycin can be inferred from erythromycin.
[1] Susceptibility to azithromycin and clarithromycin can be inferred from erythromycin.
[A] Susceptibility to doxycycline can be inferred from tetracycline.
[1] Susceptibility to doxycycline can be inferred from tetracycline.
[1] The breakpoints are based on epidemiological cut-off values (ECOFFs) and apply to oral treatment of C. difficile infections. There are no conclusive clinical data regarding the relation between MICs and outcomes.
[1] The breakpoints are based on epidemiological cut-off values (ECOFFs) and apply to oral treatment of C. difficile infections. There are no conclusive clinical data regarding the relation between MICs and outcomes.
[1] The breakpoints are based on epidemiological cut-off values (ECOFFs) and apply to oral treatment of C. difficile infections. There are no conclusive clinical data regarding the relation between MICs and outcomes.
[1] Inducible clindamycin resistance may occur in Corynebacterium spp. This can be detected by antagonism of clindamycin activity by a macrolide agent. The clinical significance is unknown. There is currently no recommendation for testing.
[1] Inducible clindamycin resistance may occur in Corynebacterium spp. This can be detected by antagonism of clindamycin activity by a macrolide agent. The clinical significance is unknown. There is currently no recommendation for testing.
[A] Non-wild typeisolates were not available when developing the disk diffusion method.
[1] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported susceptible to amoxicillin. Isolates resistant to benzylpenicillin should be tested for susceptibility to amoxicillin or reported resistant.
[1] Wild-type C. ulcerans is less susceptible to clindamycin.
[1] Wild-type C. ulcerans is less susceptible to clindamycin.
[A] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported "susceptible, increased exposure” (I) to cefotaxime. Isolates resistant to benzylpenicillin should be tested for susceptibility to cefotaxime or reported resistant.
[1] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported "susceptible, increased exposure” (I) to cefotaxime. Isolates resistant to benzylpenicillin should be tested for susceptibility to cefotaxime or reported resistant.
[1] Isolates susceptible to tetracycline can be reported susceptible to doxycycline. Isolates resistant to tetracycline should be tested for susceptibility to doxycycline or reported resistant.
[A] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported susceptible to meropenem. Isolates resistant to benzylpenicillin should be tested for susceptibility to meropenem or reported resistant.
[1] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported susceptible to meropenem. Isolates resistant to benzylpenicillin should be tested for susceptibility to meropenem or reported resistant.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported susceptible to amoxicillin. Isolates resistant to benzylpenicillin should be tested for susceptibility to amoxicillin or reported resistant.
[A] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported "susceptible, increased exposure” (I) to cefotaxime. Isolates resistant to benzylpenicillin should be tested for susceptibility to cefotaxime or reported resistant.
[1] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported "susceptible, increased exposure” (I) to cefotaxime. Isolates resistant to benzylpenicillin should be tested for susceptibility to cefotaxime or reported resistant.
[1] Isolates susceptible to tetracycline can be reported susceptible to doxycycline. Isolates resistant to tetracycline should be tested for susceptibility to doxycycline or reported resistant.
[A] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported susceptible to meropenem. Isolates resistant to benzylpenicillin should be tested for susceptibility to meropenem or reported resistant.
[1] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported susceptible to meropenem. Isolates resistant to benzylpenicillin should be tested for susceptibility to meropenem or reported resistant.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[D] Examine zones carefully for colonies within zones. Colonies should be taken into account when reading.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [C] Susceptibility to ceftriaxone can be inferred from the cefotaxime disk diffusion test.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [C] Susceptibility to ceftriaxone can be inferred from the cefotaxime disk diffusion test.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[F] Ignore isolated colonies within the inhibition zone.
[6] Agar dilution is the reference method for mecillinam MIC determination.
[A] For other Enterobacterales, the activity of tigecycline varies from insufficient in Serratia spp., Proteus spp., Morganella morganii and Providencia spp. to variable in other species. For more information, see https://www.eucast.org/eucastguidancedocuments/. | [B] Zone diameter breakpoints validated for E. coli only. For C. koseri, use an MIC method.
[2] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [3] For other Enterobacterales, the activity of tigecycline varies from insufficient in Serratia spp., Proteus spp., Morganella morganii and Providencia spp. to variable in other species. For more information, see https://www.eucast.org/eucastguidancedocuments/.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[C] Examine zones carefully for colonies within zones. Colonies should be taken into account when reading.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [4] For susceptibility testing purposes, the concentration of  tazobactam is fixed at 4 mg/L.
[F] Ignore isolated colonies within the inhibition zone.
[6] Agar dilution is the reference method for mecillinam MIC determination.
[A] For E. faecalis that test resistant to ampicillin with disk diffusion, confirm with an MIC test.
[1] Susceptibility can be inferred from ampicillin.
[1] Susceptibility can be inferred from ampicillin.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[C]  | [C] Susceptibility to ciprofloxacin and levofloxacin can be inferred from the norfloxacin disk diffusion screening test. For moxifloxacin, see comment 1/B.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Vancomycin susceptible E. faecalis and E. faecium exhibit sharp zone edges and do not exhibit colonies in the inhibition zone. Examine zone edges with transmitted light (plate held up to light). If the zone edge is fuzzy, colonies grow within the zone  or if you are uncertain, then perform confirmatory testing with PCR or report resistant (see pictures below) even if the zone diameter is ≥ 12 mm. Isolates must not be reported susceptible before 24 h incubation.
[3] Isolates susceptible to ampicillin are without phenotypically detectable resistance mechanisms and the specified agents can be used in high exposure in combination therapy (see Note 4/D). Isolates resistant to ampicillin can be reported resistant. | [4] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[2] The addition of a beta-lactamase inhibitor does not add clinical benefit. Beta-lactamase producing enterococci are extremely rare.
[5] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L. | [2] The addition of a beta-lactamase inhibitor does not add clinical benefit. Beta-lactamase producing enterococci are extremely rare.
[A] Vancomycin susceptible E. faecalis and E. faecium exhibit sharp zone edges and do not exhibit colonies in the inhibition zone. Examine zone edges with transmitted light (plate held up to light). If the zone edge is fuzzy, colonies grow within the zone  or if you are uncertain, then perform confirmatory testing with PCR or report resistant (see pictures below) even if the zone diameter is ≥ 12 mm. Isolates must not be reported susceptible before 24 h incubation.
[A] Isolates susceptible to cefadroxil and/or cefalexin can be reported "susceptible, increased exposure” (I) to cefazolin.
[2] Isolates susceptible to cefadroxil and/or cefalexin can be reported "susceptible, increased exposure” (I) to cefazolin.
[D] Ignore isolated colonies within the inhibition zone (see pictures below).
[D] Ignore isolated colonies within the inhibition zone (see pictures below).
[4] Agar dilution is the reference method for fosfomycin. MICs must be determined in the presence of glucose-6-phosphate (25 mg/L in the medium). Follow the manufacturers' instructions for commercial systems.
[4] Agar dilution is the reference method for fosfomycin. MICs must be determined in the presence of glucose-6-phosphate (25 mg/L in the medium). Follow the manufacturers' instructions for commercial systems.
[F] Ignore isolated colonies within the inhibition zone.
[6] Agar dilution is the reference method for mecillinam MIC determination.
[F] Ignore isolated colonies within the inhibition zone.
[A] For other Enterobacterales, the activity of tigecycline varies from insufficient in Serratia spp., Proteus spp., Morganella morganii and Providencia spp. to variable in other species. For more information, see https://www.eucast.org/eucastguidancedocuments/. | [B] Zone diameter breakpoints validated for E. coli only. For C. koseri, use an MIC method.
[2] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [3] For other Enterobacterales, the activity of tigecycline varies from insufficient in Serratia spp., Proteus spp., Morganella morganii and Providencia spp. to variable in other species. For more information, see https://www.eucast.org/eucastguidancedocuments/.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[C] Examine zones carefully for colonies within zones. Colonies should be taken into account when reading.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [4] For susceptibility testing purposes, the concentration of  tazobactam is fixed at 4 mg/L.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[5] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[5] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below. | [2] Beta-lactamase positive isolates can be reported resistant to ampicillin, amoxicillin and piperacillin without inhibitors. Tests based on a chromogenic cephalosporin can be used to detect the beta-lactamase.
[2] Beta-lactamase positive isolates can be reported resistant to ampicillin, amoxicillin and piperacillin without inhibitors. Tests based on a chromogenic cephalosporin can be used to detect the beta-lactamase.
[2] Beta-lactamase positive isolates can be reported resistant to ampicillin, amoxicillin and piperacillin without inhibitors. Tests based on a chromogenic cephalosporin can be used to detect the beta-lactamase.
[2] Beta-lactamase positive isolates can be reported resistant to ampicillin, amoxicillin and piperacillin without inhibitors. Tests based on a chromogenic cephalosporin can be used to detect the beta-lactamase.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[1] For chloramphenicol treatment in meningitis, see table of dosages.
[1] For chloramphenicol treatment in meningitis, see table of dosages.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below. | [3] See table of dosages for dosing for different indications.
[3] See table of dosages for dosing for different indications.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all carbapenems for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all carbapenems for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all carbapenems for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all carbapenems for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[B]  | [B] Isolates categorised as screen negative can be reported susceptible to ciprofloxacin, levofloxacin, moxifloxacin and ofloxacin. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for Gram-positive organisms and nalidixic acid for H. influenzae and M. catarrhalis).
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[1/A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[3] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L. | [4] Susceptibility can be inferred from amoxicillin-clavulanic acid iv.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[6] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[2] Susceptibility can be inferred from benzylpenicillin susceptibility.
[2] Susceptibility can be inferred from benzylpenicillin susceptibility.
[1] Susceptibility can be inferred from erythromycin susceptibility.
[1] Susceptibility can be inferred from erythromycin susceptibility.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline. Isolates categorised as resistant should be tested for susceptibility to doxycycline or reported resistant.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Isolates susceptible to cefadroxil and/or cefalexin can be reported "susceptible, increased exposure” (I) to cefazolin.
[2] Isolates susceptible to cefadroxil and/or cefalexin can be reported "susceptible, increased exposure” (I) to cefazolin.
[F] Ignore isolated colonies within the inhibition zone.
[6] Agar dilution is the reference method for mecillinam MIC determination.
[F] Ignore isolated colonies within the inhibition zone.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[1] Erythromycin can be used to screen for macrolide resistance in Moraxella catarrhalis. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[1] Erythromycin can be used to screen for macrolide resistance in Moraxella catarrhalis. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[A] Erythromycin can be used to screen for macrolide resistance in Moraxella catarrhalis. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[B]  | [B] Isolates categorised as screen negative can be reported susceptible to ciprofloxacin, levofloxacin, moxifloxacin and ofloxacin. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for Gram-positive organisms and nalidixic acid for H. influenzae and M. catarrhalis).
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[1] Erythromycin can be used to screen for macrolide resistance in Moraxella catarrhalis. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L. | [3] Susceptibility can be inferred from amoxicillin-clavulanic acid.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[1] Breakpoints were not determined with the EUCAST reference method. Therefore they are provisory values that might change according to the results on ongoing studies using the EUCAST reference protocol for MIC determination.
[1] Breakpoints were not determined with the EUCAST reference method. Therefore they are provisory values that might change according to the results on ongoing studies using the EUCAST reference protocol for MIC determination.
[1] Always test for beta-lactamase (tests based on a chromogenic cephalosporin can be used). If beta-lactamase positive, report resistant to ampicillin and amoxicillin. If beta-lactamase negative, determine the MIC of benzylpenicillin. Infer the susceptibility to ampicillin and amoxicillin from the benzylpenicillin MIC (do not report benzylpenicillin susceptibility).
[1] For chloramphenicol treatment in meningitis, see table of dosages.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory. | [2] Breakpoints for serious N. meningitidis systemic infections (meningitis with or without septicemia) have been determined for meropenem only.
[1] Tetracycline can be used to predict susceptibility to minocycline for prophylaxis against N. meningitidis infections.
[1] Tetracycline can be used to predict susceptibility to minocycline for prophylaxis against N. meningitidis infections.
[F] Ignore isolated colonies within the inhibition zone.
[6] Agar dilution is the reference method for mecillinam MIC determination.
[F] Ignore isolated colonies within the inhibition zone.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[C] Examine zones carefully for colonies within zones. Colonies should be taken into account when reading.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[2] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [1] Colistin MIC determination should be performed with broth microdilution. Quality control must be performed with both a susceptible QC strain (E. coli ATCC 25922 or P. aeruginosa ATCC 27853) and the colistin resistant E. coli NCTC 13846 (mcr-1 positive).
[2] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[3] For susceptibility testing purposes, the concentration of avibactam is fixed at 4 mg/L.
[4] See table of dosages for dosing for different indications.
[5] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L. | [4] See table of dosages for dosing for different indications.
[2] Broth microdilution MIC determination must be performed in iron-depleted Mueller-Hinton broth and specific reading instructions must be followed. For testing conditions and reading instructions, see https://www.eucast.org/eucastguidancedocuments/.
[1] For susceptibility testing purposes, the concentration of relebactam is fixed at 4 mg/L.
[2] For susceptibility testing purposes, the concentration of vaborbactam is fixed at 8 mg/L.
[1] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note B.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note B.
[B] Isolates categorised as screen negative can be reported susceptible to ciprofloxacin and levofloxacin. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Susceptibility to doxycycline can be inferred from the tetracycline disk diffusion screening test.
[1] There is clinical evidence for ciprofloxacin to indicate a poor response in systemic infections caused by Salmonella spp. with any detectable fluoroquinolone resistance mechanisms. The available data relate mainly to Salmonella Typhi but there are also case reports of poor response with other Salmonella species.
[A] There may be growth within the inhibition zone. The density of growth may vary from a fine haze to substantial growth (see pictures below). If any zone edge can be seen, ignore growth within the inhibition zone and read the zone diameter. | [1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Erythromycin can be used to screen for macrolide resistance in staphylococci. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[B] Place the erythromycin and clindamycin disks 12-20 mm apart (edge to edge) and look for antagonism (the D phenomenon) to detect inducible clindamycin resistance. | [2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant and consider adding this comment to the report: "Clindamycin may still be used for short-term therapy of less serious skin and soft tissue infections as constitutive resistance is unlikely to develop during such therapy".
[2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant and consider adding this comment to the report: "Clindamycin may still be used for short-term therapy of less serious skin and soft tissue infections as constitutive resistance is unlikely to develop during such therapy".
[1] Erythromycin can be used to screen for macrolide resistance in staphylococci. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[3] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturers' instructions for commercial systems.
[2] Daptomycin MICs must be determined in the presence of Ca (50 mg/L in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturers' instructions for commercial systems. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[A] Erythromycin can be used to screen for macrolide resistance in staphylococci. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Erythromycin can be used to screen for macrolide resistance in staphylococci. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[D]  | [D] Isolates categorised as screen negative can be reported susceptible to moxifloxacin and "susceptible increased exposure" (I) to levofloxacin. For ciprofloxacin, the isolate is without phenotypically detectable resistance mechanisms and can be used in high exposure in combination therapy (see Note 2/A). Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Erythromycin can be used to screen for macrolide resistance in staphylococci. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[4] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[4] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[2] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[3] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [2] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Isolates susceptible to linezolid can be reported susceptible to tedizolid.
[1] Isolates susceptible to linezolid can be reported susceptible to tedizolid.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[F] Methicillin-susceptible isolates can be reported susceptible to ceftobiprole without further testing.
[9] Methicillin-susceptible isolates can be reported susceptible to ceftobiprole without further testing.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [B] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[2] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[D] Methicillin-susceptible isolates can be reported susceptible to ceftaroline without further testing.
[D] Methicillin-susceptible isolates can be reported susceptible to ceftaroline without further testing.
[7] Methicillin-susceptible isolates can be reported susceptible to ceftaroline without further testing.
[7] Methicillin-susceptible isolates can be reported susceptible to ceftaroline without further testing.
[B] For MRSA that test susceptible with disk diffusion, the results should be confirmed with an MIC test.
[A] Susceptibility of staphylococci to cephalosporins is inferred from the cefoxitin susceptibility except for cefixime, ceftazidime, ceftazidime-avibactam, ceftibuten and ceftolozane-tazobactam, which do not have breakpoints and should not be used for staphylococcal infections. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. If cefotaxime and ceftriaxone are reported for methicillin-susceptible staphylococci, these should be reported “Susceptible, increased exposure” (I). Some methicillin-resistant S. aureus are susceptible to ceftaroline and ceftobiprole, see Notes 7/D and 9/F. | [B] If coagulase-negative staphylococci are not identified to species level, use zone diameter breakpoints S≥25, R<25 mm, with an ATU of 22-24 mm. For isolates with results inside the ATU: identify species, perform PCR for mecA/mecC or report resistant.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[B] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[B] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note | [3] Ofloxacin breakpoints for Staphylococcus spp. have been removed since in systemic infections with staphylococci the agent is inferior to other fluoroquinolones. For topical use of ofloxacin, see tables of topical agents.
[3] Ofloxacin breakpoints for Staphylococcus spp. have been removed since in systemic infections with staphylococci the agent is inferior to other fluoroquinolones. For topical use of ofloxacin, see tables of topical agents.
[2] Breakpoints for nasal decolonization in carriers of S. aureus, S ≤1, R >1 mg/L (disk diffusion with mupirocin 200 µg disk S ≥30, R <30 mm). For short term suppression of nasal colonization (usually as a perioperative practice) breakpoints of S ≤256, R >256 mg/L (disk diffusion S ≥18 mm, R <18 mm) can be used.
[2] Breakpoints for nasal decolonization in carriers of S. aureus, S ≤1, R >1 mg/L (disk diffusion with mupirocin 200 µg disk S ≥30, R <30 mm). For short term suppression of nasal colonization (usually as a perioperative practice) breakpoints of S ≤256, R >256 mg/L (disk diffusion S ≥18 mm, R <18 mm) can be used.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for Gram-positive organisms and nalidixic acid for H. influenzae and M. catarrhalis).
[3] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturers' instructions for commercial systems.
[A] Most S. aureus are penicillinase producers and some are methicillin resistant. Either mechanism renders them resistant to benzylpenicillin, phenoxymethylpenicillin, ampicillin, amoxicillin, piperacillin and ticarcillin. Isolates that test susceptible to benzylpenicillin and cefoxitin can be reported susceptible to all penicillins. Isolatesthat test resistant to benzylpenicillin but susceptible to cefoxitin are susceptible to β-lactam β-lactamase inhibitor combinations, the isoxazolylpenicillins (oxacillin, cloxacillin, dicloxacillin and flucloxacillin) and nafcillin. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. Isolates that test resistant to cefoxitin are resistant to all penicillins. | [B] For S. aureus, disk diffusion is more reliable than MIC determination for detection of penicillinase producers, provided the zone diameter is measured AND the zone edge for isolates with zone diameters ≥26 mm is closely inspected (see pictures below). Examine the zone edge with transmitted light (plate held up to light). If the zone diameter is <26 mm, then report resistant. If the zone diameter is ≥26 mm AND the zone edge is sharp (no reduction of growth towards zone edge, like a "cliff"), then report resistant. If not sharp (reduction of growth towards zone edge,  like a "beach"), then report susceptible and if uncertain, then report resistant. Chromogenic cephalosporin-based beta-lactamase tests do not reliably detect staphylococcal penicillinase.
[1] Most S. aureus are penicillinase producers and some are methicillin resistant. Either mechanism renders them resistant to benzylpenicillin, phenoxymethylpenicillin, ampicillin, amoxicillin, piperacillin and ticarcillin. Isolates that test susceptible to benzylpenicillin and cefoxitin can be reported susceptible to all penicillins. Isolatesthat test resistant to benzylpenicillin but susceptible to cefoxitin are susceptible to β-lactam β-lactamase inhibitor combinations, the isoxazolylpenicillins (oxacillin, cloxacillin, dicloxacillin and flucloxacillin) and nafcillin. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. Isolates that test resistant to cefoxitin are resistant to all penicillins.
[3] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturers' instructions for commercial systems.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[E] For screening for methicillin resistance in S. pseudintermedius, S. intermedius, S. schleiferi and S. coagulans.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [B] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[2] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] Susceptibility of staphylococci to cephalosporins is inferred from the cefoxitin susceptibility except for cefixime, ceftazidime, ceftazidime-avibactam, ceftibuten and ceftolozane-tazobactam, which do not have breakpoints and should not be used for staphylococcal infections. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. If cefotaxime and ceftriaxone are reported for methicillin-susceptible staphylococci, these should be reported “Susceptible, increased exposure” (I). Some methicillin-resistant S. aureus are susceptible to ceftaroline and ceftobiprole, see Notes 7/D and 9/F. | [B] If coagulase-negative staphylococci are not identified to species level, use zone diameter breakpoints S≥25, R<25 mm, with an ATU of 22-24 mm. For isolates with results inside the ATU: identify species, perform PCR for mecA/mecC or report resistant.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[B] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[B] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note | [3] Ofloxacin breakpoints for Staphylococcus spp. have been removed since in systemic infections with staphylococci the agent is inferior to other fluoroquinolones. For topical use of ofloxacin, see tables of topical agents.
[3] Ofloxacin breakpoints for Staphylococcus spp. have been removed since in systemic infections with staphylococci the agent is inferior to other fluoroquinolones. For topical use of ofloxacin, see tables of topical agents.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] Susceptibility of staphylococci to cephalosporins is inferred from the cefoxitin susceptibility except for cefixime, ceftazidime, ceftazidime-avibactam, ceftibuten and ceftolozane-tazobactam, which do not have breakpoints and should not be used for staphylococcal infections. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. If cefotaxime and ceftriaxone are reported for methicillin-susceptible staphylococci, these should be reported “Susceptible, increased exposure” (I). Some methicillin-resistant S. aureus are susceptible to ceftaroline and ceftobiprole, see Notes 7/D and 9/F. | [B] If coagulase-negative staphylococci are not identified to species level, use zone diameter breakpoints S≥25, R<25 mm, with an ATU of 22-24 mm. For isolates with results inside the ATU: identify species, perform PCR for mecA/mecC or report resistant.
[E] For screening for methicillin resistance in S. pseudintermedius, S. intermedius, S. schleiferi and S. coagulans.
[A] Susceptibility of staphylococci to cephalosporins is inferred from the cefoxitin susceptibility except for cefixime, ceftazidime, ceftazidime-avibactam, ceftibuten and ceftolozane-tazobactam, which do not have breakpoints and should not be used for staphylococcal infections. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. If cefotaxime and ceftriaxone are reported for methicillin-susceptible staphylococci, these should be reported “Susceptible, increased exposure” (I). Some methicillin-resistant S. aureus are susceptible to ceftaroline and ceftobiprole, see Notes 7/D and 9/F. | [B] If coagulase-negative staphylococci are not identified to species level, use zone diameter breakpoints S≥25, R<25 mm, with an ATU of 22-24 mm. For isolates with results inside the ATU: identify species, perform PCR for mecA/mecC or report resistant.
[E] For screening for methicillin resistance in S. pseudintermedius, S. intermedius, S. schleiferi and S. coagulans.
[E] For screening for methicillin resistance in S. pseudintermedius, S. intermedius, S. schleiferi and S. coagulans.
[C] Most staphylococci are penicillinase producers and some are methicillin resistant. Either mechanism renders them resistant to benzylpenicillin, phenoxymethylpenicillin, ampicillin, amoxicillin, piperacillin and ticarcillin. No currently available method can reliably detect penicillinase production in all species of staphylococci but methicillin resistance can be detected with cefoxitin as described. | [D] Ampicillin susceptible S. saprophyticus are mecA-negative and susceptible to ampicillin, amoxicillin and piperacillin (without or with a beta-lactamase inhibitor).
[1] Erythromycin can be used to screen for macrolide resistance in Streptococcus groups A, B, C and
[B] Place the erythromycin and clindamycin disks 12-16 mm apart (edge to edge) and look for antagonism (the D phenomenon) to detect inducible clindamycin resistance. | [2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant and consider adding this comment to the report: "Clindamycin may still be used for short-term therapy of less serious skin and soft tissue infections as constitutive resistance is unlikely to develop during such therapy". The clinical importance of inducible clindamycin resistance in combination treatment of severe S. pyogenes infections is not known.
[2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant and consider adding this comment to the report: "Clindamycin may still be used for short-term therapy of less serious skin and soft tissue infections as constitutive resistance is unlikely to develop during such therapy". The clinical importance of inducible clindamycin resistance in combination treatment of severe S. pyogenes infections is not known.
[1] Erythromycin can be used to screen for macrolide resistance in Streptococcus groups A, B, C and
[2] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturers' instructions for commercial systems. | [3] Isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] Daptomycin MICs must be determined in the presence of Ca (50 mg/L in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturers' instructions for commercial systems. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[A] Erythromycin can be used to screen for macrolide resistance in Streptococcus groups A, B, C and
[1] Erythromycin can be used to screen for macrolide resistance in Streptococcus groups A, B, C and
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[B] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[B] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[C]  | [C] Isolates categorised as screen negative can be reported susceptible to moxifloxacin and as "susceptible increased exposure" (I) to levofloxacin. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for Gram-positive organisms and nalidixic acid for H. influenzae and M. catarrhalis).
[2] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturers' instructions for commercial systems. | [3] Isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Erythromycin can be used to screen for macrolide resistance in Streptococcus groups A, B, C and
[4] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[4] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[B] Non-wild type isolates were not available when developing the disk diffusion method. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[3] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [2] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Isolates susceptible to linezolid can be reported susceptible to tedizolid. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] Isolates susceptible to linezolid can be reported susceptible to tedizolid. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[B] Non-wild type isolates were not available when developing the disk diffusion method. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturers' instructions for commercial systems. | [3] Isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturers' instructions for commercial systems. | [3] Isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L. | [2] The addition of a beta-lactamase inhibitor does not add clinical benefit.
[1] Erythromycin can be used to screen for macrolide resistance in Streptococcus pneumoniae. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[B] Place the erythromycin and clindamycin disks 12-16 mm apart (edge to edge) and look for antagonism (the D phenomenon) to detect inducible clindamycin resistance. | [2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant.
[2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant.
[1] Erythromycin can be used to screen for macrolide resistance in Streptococcus pneumoniae. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[A] Erythromycin can be used to screen for macrolide resistance in Streptococcus pneumoniae. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Erythromycin can be used to screen for macrolide resistance in Streptococcus pneumoniae. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[B]  | [B] Isolates categorised as screen negative can be reported susceptible to moxifloxacin and as "susceptible increased exposure" (I) to levofloxacin. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for Gram-positive organisms and nalidixic acid for H. influenzae and M. catarrhalis).
[D] For interpretation of the oxacillin disk screen, see flow chart below. | [1] The oxacillin 1 µg disk diffusion screening test or a benzylpenicillin MIC test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (oxacillin zone diameter ≥20 mm, or benzylpenicillin MIC ≤0.06 mg/L) all beta-lactam agents for which clinical breakpoints are available, including those with “Note” can be reported susceptible without further testing, except for cefaclor, which if reported, should be reported as “susceptible, increased exposure” (I). When the screen is positive (zone diameter <20 mm, or benzylpenicillin MIC >0.06 mg/L), see flow chart below.
[1] Erythromycin can be used to screen for macrolide resistance in Streptococcus pneumoniae. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[A] Non-wild typeisolates were not available when developing the disk diffusion method. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Non-wild typeisolates were not available when developing the disk diffusion method. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Place the erythromycin and clindamycin disks 12-16 mm apart (edge to edge) and look for antagonism (the D phenomenon) to detect inducible clindamycin resistance. | [1] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant.
[1] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant.
[A] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. See Note 1/A on penicillins.
[A] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. See Note 1/A on penicillins.
[A] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. See Note 1/A on penicillins.
[A] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. See Note 1/A on penicillins.
[1] For susceptibility testing purposes, the concentration of relebactam is fixed at 4 mg/L. | [2] The addition of a beta-lactamase inhibitor does not add clinical benefit.
[A] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. Isolates categorised as screen negative can be reported susceptible to beta-lactam agents for which clinical breakpoints are listed (including those with “Note”). Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[B] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. Isolates categorised as screen negative can be reported susceptible to beta-lactam agents for which clinical breakpoints are listed (including those with “Note”). Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[2] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[B] Non-wild type isolates were not available when developing the disk diffusion method. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[B] Non-wild type isolates were not available when developing the disk diffusion method. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Susceptibility to azithromycin (and erythromycin when azithromycin is not available) is inferred from the erythromycin disk diffusion test.
[A] Susceptibility to ciprofloxacin and levofloxacin can be inferred from the pefloxacin disk diffusion screening test.
[1/A] Susceptibility to azithromycin (and erythromycin when azithromycin is not available) is inferred from the erythromycin disk diffusion test.
[A] Susceptibility to ciprofloxacin and levofloxacin can be inferred from the pefloxacin disk diffusion screening test.
[A] Susceptibility to ciprofloxacin and levofloxacin can be inferred from the pefloxacin disk diffusion screening test.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1/A] Susceptibility to doxycycline (and tetracycline when doxycycline is not available) is inferred from the tetracycline disk diffusion test.
[1] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[2] The intrinsically low activity of imipenem against Morganella morganii, Proteus spp. and Providencia spp. requires the high exposure of imipenem.
[2] The intrinsically low activity of imipenem against Morganella morganii, Proteus spp. and Providencia spp. requires the high exposure of imipenem.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [D] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[3] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[3] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[1] The aztreonam breakpoints for Enterobacterales will detect clinically important resistance mechanisms (including ESBL). Some isolates that produce beta-lactamases are susceptible to aztreonam with these breakpoints and should be reported as tested, i.e. the presence or absence of an ESBL does not in itself influence the categorisation of susceptibility. ESBL detection and characterisation are recommended for public health and infection control purposes.
[1] The aztreonam breakpoints for Enterobacterales will detect clinically important resistance mechanisms (including ESBL). Some isolates that produce beta-lactamases are susceptible to aztreonam with these breakpoints and should be reported as tested, i.e. the presence or absence of an ESBL does not in itself influence the categorisation of susceptibility. ESBL detection and characterisation are recommended for public health and infection control purposes.
[2] For susceptibility testing purposes, the concentration of avibactam is fixed at 4 mg/L.
[2] In meningitis, where all fluoroquinolone resistance mechanisms must be excluded, either perform an MIC test, or infer susceptibility from the pefloxacin 5 µg screening test.
[3] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [2] Colistin MIC determination should be performed with broth microdilution. Quality control must be performed with both a susceptible QC strain (E. coli ATCC 25922 or P. aeruginosa ATCC 27853) and the colistin resistant E. coli NCTC 13846 (mcr-1 positive).
[6] For susceptibility testing purposes, the concentration of avibactam is fixed at 4 mg/L.
[7] See table of dosages for dosing for different indications.
[8] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L. | [7] See table of dosages for dosing for different indications.
[4] Broth microdilution MIC determination must be performed in iron-depleted Mueller-Hinton broth and specific reading instructions must be followed. For testing conditions and reading instructions, see https://www.eucast.org/eucastguidancedocuments/.
[5] The cefoxitin cut-off value (8 mg/L) has a high sensitivity but poor specificity for identification of AmpC-producing Enterobacterales as this agent is also affected by permeability alterations and some carbapenemases. Classical non-AmpC producers are wild type, whereas plasmid AmpC producers or chromosomal AmpC hyperproducers are non-wild type.
[3] For susceptibility testing purposes, the concentration of enmetazobactam is fixed at 8 mg/L.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[3] For susceptibility testing purposes, the concentration of relebactam is fixed at 4 mg/L.
[4] For susceptibility testing purposes, the concentration of vaborbactam is fixed at 8 mg/L.
[3] Fluoroquinolone breakpoints are available for other agents.
[3] Fluoroquinolone breakpoints are available for other agents.
[A] Tests with a ciprofloxacin 5 µg disk will not reliably exclude all fluoroquinolone resistance mechanisms in Salmonella spp. Perform an MIC test, or infer susceptibility from the pefloxacin 5 µg screening test. | [B] In meningitis, where all fluoroquinolone resistance mechanisms must be excluded, either perform an MIC test, or infer susceptibility from the pefloxacin 5 µg screening test. | [C] The pefloxacin screening test can also be used to detect fluoroquinolone resistance mechanisms in other Enterobacterales such as E. coli, K. pneumoniae and Shigella spp.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for Gram-positive organisms and nalidixic acid for H. influenzae and M. catarrhalis).
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[7] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[7] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[5] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[A] There may be growth within the inhibition zone. The density of growth may vary from a fine haze to substantial growth (see pictures below). If any zone edge can be seen, ignore growth within the inhibition zone and read the zone diameter. | [1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[2] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [1] Colistin MIC determination should be performed with broth microdilution. Quality control must be performed with both a susceptible QC strain (E. coli ATCC 25922 or P. aeruginosa ATCC 27853) and the colistin resistant E. coli NCTC 13846 (mcr-1 positive).
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[4] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[4] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] Susceptibility can be inferred from the norfloxacin disk diffusion screening test. See Note
[1] Susceptibility can be inferred from ciprofloxacin susceptibility.
[C]  | [C] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance.
[A] Non-wild type isolates were not available when developing the disk diffusion method.
[A] Susceptibility can be inferred from the norfloxacin disk diffusion screening test. See Note
[1] Susceptibility can be inferred from ciprofloxacin susceptibility.
[C]  | [C] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance.
[A] Non-wild type isolates were not available when developing the disk diffusion method.
[A] Read the obvious zone edge and disregard haze or growth within the inhibition zone (see pictures below). | [1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[B]  | [B] Isolates categorised as screen negative can be reported "susceptible increased exposure" (I) to ciprofloxacin and levofloxacin. Isolates categorised as screen positive can be reported resistant to ciprofloxacin and levofloxacin.
[A] Non-wild type isolates were not available when developing the disk diffusion method.
[1] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported susceptible to amoxicillin. Isolates resistant to benzylpenicillin should be tested for susceptibility to amoxicillin or reported resistant.
[1] Isolates susceptible to tetracycline can be reported susceptible to doxycycline. Isolates resistant to tetracycline should be tested for susceptibility to doxycycline or reported resistant.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[2] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [B] Examine zones carefully for colonies within zones. Colonies should be taken into account when reading.
[4] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[4] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L.
[3] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] Isolates susceptible to tetracycline can be reported susceptible to doxycycline. Isolates resistant to tetracycline should be tested for susceptibility to doxycycline or reported resistant.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [B] Examine zones carefully for colonies close to the zone edge. Colonies should be taken into account when reading.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[C] Read the obvious zone edges and disregard haze or faint growth within the inhibition zone. | [2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] There may be growth within the inhibition zone. The density of growth may vary from a fine haze to substantial growth (see pictures below). If any zone edge can be seen, ignore growth within the inhibition zone and read the zone diameter. | [1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Isolates categorised as screen negative can be reported "susceptible increased exposure" (I) to doxycyline. Isolates categorised as screen positive can be reported resistant to doxycycline.
[A] Susceptibility to azithromycin and clarithromycin can be inferred from erythromycin.
[1] Susceptibility to azithromycin and clarithromycin can be inferred from erythromycin.
[A] Susceptibility to doxycycline can be inferred from tetracycline.
[1] Susceptibility to doxycycline can be inferred from tetracycline.
[A] Susceptibility to azithromycin and clarithromycin can be inferred from erythromycin.
[1] Susceptibility to azithromycin and clarithromycin can be inferred from erythromycin.
[A] Susceptibility to doxycycline can be inferred from tetracycline.
[1] Susceptibility to doxycycline can be inferred from tetracycline.
[1] The breakpoints are based on epidemiological cut-off values (ECOFFs) and apply to oral treatment of C. difficile infections. There are no conclusive clinical data regarding the relation between MICs and outcomes.
[1] The breakpoints are based on epidemiological cut-off values (ECOFFs) and apply to oral treatment of C. difficile infections. There are no conclusive clinical data regarding the relation between MICs and outcomes.
[1] The breakpoints are based on epidemiological cut-off values (ECOFFs) and apply to oral treatment of C. difficile infections. There are no conclusive clinical data regarding the relation between MICs and outcomes.
[1] Inducible clindamycin resistance may occur in Corynebacterium spp. This can be detected by antagonism of clindamycin activity by a macrolide agent. The clinical significance is unknown. There is currently no recommendation for testing.
[1] Inducible clindamycin resistance may occur in Corynebacterium spp. This can be detected by antagonism of clindamycin activity by a macrolide agent. The clinical significance is unknown. There is currently no recommendation for testing.
[A] Non-wild typeisolates were not available when developing the disk diffusion method.
[1] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported susceptible to amoxicillin. Isolates resistant to benzylpenicillin should be tested for susceptibility to amoxicillin or reported resistant.
[1] Wild-type C. ulcerans is less susceptible to clindamycin.
[1] Wild-type C. ulcerans is less susceptible to clindamycin.
[A] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported "susceptible, increased exposure” (I) to cefotaxime. Isolates resistant to benzylpenicillin should be tested for susceptibility to cefotaxime or reported resistant.
[1] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported "susceptible, increased exposure” (I) to cefotaxime. Isolates resistant to benzylpenicillin should be tested for susceptibility to cefotaxime or reported resistant.
[1] Isolates susceptible to tetracycline can be reported susceptible to doxycycline. Isolates resistant to tetracycline should be tested for susceptibility to doxycycline or reported resistant.
[A] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported susceptible to meropenem. Isolates resistant to benzylpenicillin should be tested for susceptibility to meropenem or reported resistant.
[1] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported susceptible to meropenem. Isolates resistant to benzylpenicillin should be tested for susceptibility to meropenem or reported resistant.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported susceptible to amoxicillin. Isolates resistant to benzylpenicillin should be tested for susceptibility to amoxicillin or reported resistant.
[A] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported "susceptible, increased exposure” (I) to cefotaxime. Isolates resistant to benzylpenicillin should be tested for susceptibility to cefotaxime or reported resistant.
[1] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported "susceptible, increased exposure” (I) to cefotaxime. Isolates resistant to benzylpenicillin should be tested for susceptibility to cefotaxime or reported resistant.
[1] Isolates susceptible to tetracycline can be reported susceptible to doxycycline. Isolates resistant to tetracycline should be tested for susceptibility to doxycycline or reported resistant.
[A] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported susceptible to meropenem. Isolates resistant to benzylpenicillin should be tested for susceptibility to meropenem or reported resistant.
[1] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported susceptible to meropenem. Isolates resistant to benzylpenicillin should be tested for susceptibility to meropenem or reported resistant.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[D] Examine zones carefully for colonies within zones. Colonies should be taken into account when reading.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [C] Susceptibility to ceftriaxone can be inferred from the cefotaxime disk diffusion test.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [C] Susceptibility to ceftriaxone can be inferred from the cefotaxime disk diffusion test.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[F] Ignore isolated colonies within the inhibition zone.
[6] Agar dilution is the reference method for mecillinam MIC determination.
[A] For other Enterobacterales, the activity of tigecycline varies from insufficient in Serratia spp., Proteus spp., Morganella morganii and Providencia spp. to variable in other species. For more information, see https://www.eucast.org/eucastguidancedocuments/. | [B] Zone diameter breakpoints validated for E. coli only. For C. koseri, use an MIC method.
[2] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [3] For other Enterobacterales, the activity of tigecycline varies from insufficient in Serratia spp., Proteus spp., Morganella morganii and Providencia spp. to variable in other species. For more information, see https://www.eucast.org/eucastguidancedocuments/.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[C] Examine zones carefully for colonies within zones. Colonies should be taken into account when reading.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [4] For susceptibility testing purposes, the concentration of  tazobactam is fixed at 4 mg/L.
[F] Ignore isolated colonies within the inhibition zone.
[6] Agar dilution is the reference method for mecillinam MIC determination.
[2] In E. faecalis, susceptibility to ampicillin, amoxicillin and piperacillin (with and without beta-lactamase inhibitor) is the expected phenotype, while in E. faecium, resistance is common. Isolates resistant to ampicillin can be reported resistant to ampicillin, amoxicillin and piperacillin (with or without inhibitor). For E. faecalis that test resistant to ampicillin with disk diffusion, confirm with an MIC test. | [4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L. | [1] Aminopenicillin breakpoints in enterococci are based on intravenous administration. For oral administration the breakpoints are relevant for urinary tract infections only.
[A] In E. faecalis, susceptibility to ampicillin, amoxicillin and piperacillin (with and without beta-lactamase inhibitor) is the expected phenotype, while in E. faecium, resistance is common. Isolates resistant to ampicillin can be reported resistant to ampicillin, amoxicillin and piperacillin (with or without inhibitor). For E. faecalis that test resistant to ampicillin with disk diffusion, confirm with an MIC test. | [1] Aminopenicillin breakpoints in enterococci are based on intravenous administration. For oral administration the breakpoints are relevant for urinary tract infections only.
[2] In E. faecalis, susceptibility to ampicillin, amoxicillin and piperacillin (with and without beta-lactamase inhibitor) is the expected phenotype, while in E. faecium, resistance is common. Isolates resistant to ampicillin can be reported resistant to ampicillin, amoxicillin and piperacillin (with or without inhibitor). For E. faecalis that test resistant to ampicillin with disk diffusion, confirm with an MIC test. | [1] Aminopenicillin breakpoints in enterococci are based on intravenous administration. For oral administration the breakpoints are relevant for urinary tract infections only.
[2] In E. faecalis, susceptibility to ampicillin, amoxicillin and piperacillin (with and without beta-lactamase inhibitor) is the expected phenotype, while in E. faecium, resistance is common. Isolates resistant to ampicillin can be reported resistant to ampicillin, amoxicillin and piperacillin (with or without inhibitor). For E. faecalis that test resistant to ampicillin with disk diffusion, confirm with an MIC test. | [1] Aminopenicillin breakpoints in enterococci are based on intravenous administration. For oral administration the breakpoints are relevant for urinary tract infections only.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[C]  | [C] Susceptibility to ciprofloxacin and levofloxacin can be inferred from the norfloxacin disk diffusion screening test. For moxifloxacin, see comment 1/B.
[2] In E. faecalis, susceptibility to ampicillin, amoxicillin and piperacillin (with and without beta-lactamase inhibitor) is the expected phenotype, while in E. faecium, resistance is common. Isolates resistant to ampicillin can be reported resistant to ampicillin, amoxicillin and piperacillin (with or without inhibitor). For E. faecalis that test resistant to ampicillin with disk diffusion, confirm with an MIC test. | [3] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L. | [1] Aminopenicillin breakpoints in enterococci are based on intravenous administration. For oral administration the breakpoints are relevant for urinary tract infections only.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Isolates susceptible to cefadroxil and/or cefalexin can be reported "susceptible, increased exposure” (I) to cefazolin.
[2] Isolates susceptible to cefadroxil and/or cefalexin can be reported "susceptible, increased exposure” (I) to cefazolin.
[D] Ignore isolated colonies within the inhibition zone (see pictures below).
[D] Ignore isolated colonies within the inhibition zone (see pictures below).
[4] Agar dilution is the reference method for fosfomycin. MICs must be determined in the presence of glucose-6-phosphate (25 mg/L in the medium). Follow the manufacturers' instructions for commercial systems.
[4] Agar dilution is the reference method for fosfomycin. MICs must be determined in the presence of glucose-6-phosphate (25 mg/L in the medium). Follow the manufacturers' instructions for commercial systems.
[F] Ignore isolated colonies within the inhibition zone.
[6] Agar dilution is the reference method for mecillinam MIC determination.
[F] Ignore isolated colonies within the inhibition zone.
[A] For other Enterobacterales, the activity of tigecycline varies from insufficient in Serratia spp., Proteus spp., Morganella morganii and Providencia spp. to variable in other species. For more information, see https://www.eucast.org/eucastguidancedocuments/. | [B] Zone diameter breakpoints validated for E. coli only. For C. koseri, use an MIC method.
[2] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [3] For other Enterobacterales, the activity of tigecycline varies from insufficient in Serratia spp., Proteus spp., Morganella morganii and Providencia spp. to variable in other species. For more information, see https://www.eucast.org/eucastguidancedocuments/.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[C] Examine zones carefully for colonies within zones. Colonies should be taken into account when reading.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [4] For susceptibility testing purposes, the concentration of  tazobactam is fixed at 4 mg/L.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[5] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[5] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below. | [2] Beta-lactamase positive isolates can be reported resistant to ampicillin, amoxicillin and piperacillin without inhibitors. Tests based on a chromogenic cephalosporin can be used to detect the beta-lactamase.
[2] Beta-lactamase positive isolates can be reported resistant to ampicillin, amoxicillin and piperacillin without inhibitors. Tests based on a chromogenic cephalosporin can be used to detect the beta-lactamase.
[2] Beta-lactamase positive isolates can be reported resistant to ampicillin, amoxicillin and piperacillin without inhibitors. Tests based on a chromogenic cephalosporin can be used to detect the beta-lactamase.
[2] Beta-lactamase positive isolates can be reported resistant to ampicillin, amoxicillin and piperacillin without inhibitors. Tests based on a chromogenic cephalosporin can be used to detect the beta-lactamase.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[1] For chloramphenicol treatment in meningitis, see table of dosages.
[1] For chloramphenicol treatment in meningitis, see table of dosages.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below. | [D] For benzylpenicillin screen positive isolates (zone <12 mm), determine the MIC in meningitis.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below. | [D] For benzylpenicillin screen positive isolates (zone <12 mm), determine the MIC in meningitis.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below. | [2] See table of dosages for dosing for different indications.
[2] See table of dosages for dosing for different indications.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all carbapenems for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all carbapenems for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all carbapenems for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all carbapenems for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[C]  | [C] Isolates categorised as screen negative can be reported susceptible to ciprofloxacin, levofloxacin, moxifloxacin and ofloxacin. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for Gram-positive organisms and nalidixic acid for H. influenzae and M. catarrhalis).
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[1/A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[3] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L. | [4] Susceptibility can be inferred from amoxicillin-clavulanic acid iv.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[6] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[2] Susceptibility can be inferred from benzylpenicillin susceptibility.
[2] Susceptibility can be inferred from benzylpenicillin susceptibility.
[1] Susceptibility can be inferred from erythromycin susceptibility.
[1] Susceptibility can be inferred from erythromycin susceptibility.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline. Isolates categorised as resistant should be tested for susceptibility to doxycycline or reported resistant.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Isolates susceptible to cefadroxil and/or cefalexin can be reported "susceptible, increased exposure” (I) to cefazolin.
[2] Isolates susceptible to cefadroxil and/or cefalexin can be reported "susceptible, increased exposure” (I) to cefazolin.
[F] Ignore isolated colonies within the inhibition zone.
[6] Agar dilution is the reference method for mecillinam MIC determination.
[F] Ignore isolated colonies within the inhibition zone.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[1] Erythromycin can be used to screen for macrolide resistance in Moraxella catarrhalis. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[1] Erythromycin can be used to screen for macrolide resistance in Moraxella catarrhalis. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[A] Erythromycin can be used to screen for macrolide resistance in Moraxella catarrhalis. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[B]  | [B] Isolates categorised as screen negative can be reported susceptible to ciprofloxacin, levofloxacin, moxifloxacin and ofloxacin. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for Gram-positive organisms and nalidixic acid for H. influenzae and M. catarrhalis).
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[1] Erythromycin can be used to screen for macrolide resistance in Moraxella catarrhalis. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L. | [3] Susceptibility can be inferred from amoxicillin-clavulanic acid.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[1] Breakpoints were not determined with the EUCAST reference method. Therefore they are provisory values that might change according to the results on ongoing studies using the EUCAST reference protocol for MIC determination.
[1] Breakpoints were not determined with the EUCAST reference method. Therefore they are provisory values that might change according to the results on ongoing studies using the EUCAST reference protocol for MIC determination.
[1] Always test for beta-lactamase (tests based on a chromogenic cephalosporin can be used). If beta-lactamase positive, report resistant to ampicillin and amoxicillin. If beta-lactamase negative, determine the MIC of benzylpenicillin. Infer the susceptibility to ampicillin and amoxicillin from the benzylpenicillin MIC (do not report benzylpenicillin susceptibility).
[1] For chloramphenicol treatment in meningitis, see table of dosages.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory. | [2] Breakpoints for serious N. meningitidis systemic infections (meningitis with or without septicemia) have been determined for meropenem only.
[1] Tetracycline can be used to predict susceptibility to minocycline for prophylaxis against N. meningitidis infections.
[1] Tetracycline can be used to predict susceptibility to minocycline for prophylaxis against N. meningitidis infections.
[F] Ignore isolated colonies within the inhibition zone.
[6] Agar dilution is the reference method for mecillinam MIC determination.
[F] Ignore isolated colonies within the inhibition zone.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[C] Examine zones carefully for colonies within zones. Colonies should be taken into account when reading.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[2] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [1] Colistin MIC determination should be performed with broth microdilution. Quality control must be performed with both a susceptible QC strain (E. coli ATCC 25922 or P. aeruginosa ATCC 27853) and the colistin resistant E. coli NCTC 13846 (mcr-1 positive).
[2] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[2] For susceptibility testing purposes, the concentration of avibactam is fixed at 4 mg/L.
[3] See table of dosages for dosing for different indications.
[4] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L. | [3] See table of dosages for dosing for different indications.
[1] Broth microdilution MIC determination must be performed in iron-depleted Mueller-Hinton broth and specific reading instructions must be followed. For testing conditions and reading instructions, see https://www.eucast.org/eucastguidancedocuments/.
[1] For susceptibility testing purposes, the concentration of relebactam is fixed at 4 mg/L.
[2] For susceptibility testing purposes, the concentration of vaborbactam is fixed at 8 mg/L.
[1] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note B.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note B.
[B] Isolates categorised as screen negative can be reported susceptible to ciprofloxacin and levofloxacin. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Susceptibility to doxycycline can be inferred from the tetracycline disk diffusion screening test.
[1] There is clinical evidence for ciprofloxacin to indicate a poor response in systemic infections caused by Salmonella spp. with any detectable fluoroquinolone resistance mechanisms. The available data relate mainly to Salmonella Typhi but there are also case reports of poor response with other Salmonella species.
[A] There may be growth within the inhibition zone. The density of growth may vary from a fine haze to substantial growth (see pictures below). If any zone edge can be seen, ignore growth within the inhibition zone and read the zone diameter. | [1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Erythromycin can be used to screen for macrolide resistance in staphylococci. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[B] Place the erythromycin and clindamycin disks 12-20 mm apart (edge to edge) and look for antagonism (the D phenomenon) to detect inducible clindamycin resistance. | [2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant and consider adding this comment to the report: "Clindamycin may still be used for short-term therapy of less serious skin and soft tissue infections as constitutive resistance is unlikely to develop during such therapy".
[2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant and consider adding this comment to the report: "Clindamycin may still be used for short-term therapy of less serious skin and soft tissue infections as constitutive resistance is unlikely to develop during such therapy".
[1] Erythromycin can be used to screen for macrolide resistance in staphylococci. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[3] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturers' instructions for commercial systems. | [4] Coagulase-negative staphylococci susceptible to both vancomycin and teicoplanin can be reported susceptible to dalbavancin. | [5] S. aureus isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin.
[2] Daptomycin MICs must be determined in the presence of Ca (50 mg/L in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturers' instructions for commercial systems. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[A] Erythromycin can be used to screen for macrolide resistance in staphylococci. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Erythromycin can be used to screen for macrolide resistance in staphylococci. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[D]  | [D] Isolates categorised as screen negative can be reported susceptible to moxifloxacin and "susceptible increased exposure" (I) to levofloxacin. For ciprofloxacin, the isolate is without phenotypically detectable resistance mechanisms and can be used in high exposure in combination therapy (see Note 2/A). Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Erythromycin can be used to screen for macrolide resistance in staphylococci. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[4] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[4] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[2] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[3] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [2] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Isolates susceptible to linezolid can be reported susceptible to tedizolid.
[1] Isolates susceptible to linezolid can be reported susceptible to tedizolid.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[F] Methicillin-susceptible isolates can be reported susceptible to ceftobiprole without further testing.
[8] Methicillin-susceptible isolates can be reported susceptible to ceftobiprole without further testing.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [B] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[2] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[D] Methicillin-susceptible isolates can be reported susceptible to ceftaroline without further testing.
[D] Methicillin-susceptible isolates can be reported susceptible to ceftaroline without further testing.
[6] Methicillin-susceptible isolates can be reported susceptible to ceftaroline without further testing.
[6] Methicillin-susceptible isolates can be reported susceptible to ceftaroline without further testing.
[B] For MRSA that test susceptible with disk diffusion, the results should be confirmed with an MIC test.
[A] Susceptibility of staphylococci to cephalosporins is inferred from the cefoxitin susceptibility except for cefixime, ceftazidime, ceftazidime-avibactam, ceftibuten and ceftolozane-tazobactam, which do not have breakpoints and should not be used for staphylococcal infections. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. If cefotaxime and ceftriaxone are reported for methicillin-susceptible staphylococci, these should be reported “Susceptible, increased exposure” (I). Some methicillin-resistant S. aureus are susceptible to ceftaroline and ceftobiprole, see Notes 6/D and 8/F. | [B] If coagulase-negative staphylococci are not identified to species level, use zone diameter breakpoints S≥25, R<25 mm, with an ATU of 22-24 mm. For isolates with results inside the ATU: identify species, perform PCR for mecA/mecC or report resistant.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[B] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[B] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[2] Breakpoints for nasal decolonization in carriers of S. aureus, S ≤1, R >1 mg/L (disk diffusion with mupirocin 200 µg disk S ≥30, R <30 mm). For short term suppression of nasal colonization (usually as a perioperative practice) breakpoints of S ≤256, R >256 mg/L (disk diffusion S ≥18 mm, R <18 mm) can be used.
ND = No ECOFF available.
[2] Breakpoints for nasal decolonization in carriers of S. aureus, S ≤1, R >1 mg/L (disk diffusion with mupirocin 200 µg disk S ≥30, R <30 mm). For short term suppression of nasal colonization (usually as a perioperative practice) breakpoints of S ≤256, R >256 mg/L (disk diffusion S ≥18 mm, R <18 mm) can be used.
ND = No ECOFF available.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for Gram-positive organisms and nalidixic acid for H. influenzae and M. catarrhalis).
[3] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturers' instructions for commercial systems. | [5] S. aureus isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin.
[A] Most S. aureus are penicillinase producers and some are methicillin resistant. Either mechanism renders them resistant to benzylpenicillin, phenoxymethylpenicillin, ampicillin, amoxicillin, piperacillin and ticarcillin. Isolates that test susceptible to benzylpenicillin and cefoxitin can be reported susceptible to all penicillins. Isolatesthat test resistant to benzylpenicillin but susceptible to cefoxitin are susceptible to β-lactam β-lactamase inhibitor combinations, the isoxazolylpenicillins (oxacillin, cloxacillin, dicloxacillin and flucloxacillin) and nafcillin. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. Isolates that test resistant to cefoxitin are resistant to all penicillins. | [B] For S. aureus, disk diffusion is more reliable than MIC determination for detection of penicillinase producers, provided the zone diameter is measured AND the zone edge for isolates with zone diameters ≥26 mm is closely inspected (see pictures below). Examine the zone edge with transmitted light (plate held up to light). If the zone diameter is <26 mm, then report resistant. If the zone diameter is ≥26 mm AND the zone edge is sharp (no reduction of growth towards zone edge, like a "cliff"), then report resistant. If not sharp (reduction of growth towards zone edge,  like a "beach"), then report susceptible and if uncertain, then report resistant. Chromogenic cephalosporin-based beta-lactamase tests do not reliably detect staphylococcal penicillinase.
[1] Most S. aureus are penicillinase producers and some are methicillin resistant. Either mechanism renders them resistant to benzylpenicillin, phenoxymethylpenicillin, ampicillin, amoxicillin, piperacillin and ticarcillin. Isolates that test susceptible to benzylpenicillin and cefoxitin can be reported susceptible to all penicillins. Isolatesthat test resistant to benzylpenicillin but susceptible to cefoxitin are susceptible to β-lactam β-lactamase inhibitor combinations, the isoxazolylpenicillins (oxacillin, cloxacillin, dicloxacillin and flucloxacillin) and nafcillin. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. Isolates that test resistant to cefoxitin are resistant to all penicillins.
[3] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturers' instructions for commercial systems. | [6] MRSA isolates susceptible to vancomycin can be reported susceptible to telavancin.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[E] For screening for methicillin resistance in S. pseudintermedius, S. intermedius, S. schleiferi and S. coagulans.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [B] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[2] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] Susceptibility of staphylococci to cephalosporins is inferred from the cefoxitin susceptibility except for cefixime, ceftazidime, ceftazidime-avibactam, ceftibuten and ceftolozane-tazobactam, which do not have breakpoints and should not be used for staphylococcal infections. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. If cefotaxime and ceftriaxone are reported for methicillin-susceptible staphylococci, these should be reported “Susceptible, increased exposure” (I). Some methicillin-resistant S. aureus are susceptible to ceftaroline and ceftobiprole, see Notes 6/D and 8/F. | [B] If coagulase-negative staphylococci are not identified to species level, use zone diameter breakpoints S≥25, R<25 mm, with an ATU of 22-24 mm. For isolates with results inside the ATU: identify species, perform PCR for mecA/mecC or report resistant.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[B] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[B] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] Susceptibility of staphylococci to cephalosporins is inferred from the cefoxitin susceptibility except for cefixime, ceftazidime, ceftazidime-avibactam, ceftibuten and ceftolozane-tazobactam, which do not have breakpoints and should not be used for staphylococcal infections. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. If cefotaxime and ceftriaxone are reported for methicillin-susceptible staphylococci, these should be reported “Susceptible, increased exposure” (I). Some methicillin-resistant S. aureus are susceptible to ceftaroline and ceftobiprole, see Notes 6/D and 8/F. | [B] If coagulase-negative staphylococci are not identified to species level, use zone diameter breakpoints S≥25, R<25 mm, with an ATU of 22-24 mm. For isolates with results inside the ATU: identify species, perform PCR for mecA/mecC or report resistant.
[E] For screening for methicillin resistance in S. pseudintermedius, S. intermedius, S. schleiferi and S. coagulans.
[A] Susceptibility of staphylococci to cephalosporins is inferred from the cefoxitin susceptibility except for cefixime, ceftazidime, ceftazidime-avibactam, ceftibuten and ceftolozane-tazobactam, which do not have breakpoints and should not be used for staphylococcal infections. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. If cefotaxime and ceftriaxone are reported for methicillin-susceptible staphylococci, these should be reported “Susceptible, increased exposure” (I). Some methicillin-resistant S. aureus are susceptible to ceftaroline and ceftobiprole, see Notes 6/D and 8/F. | [B] If coagulase-negative staphylococci are not identified to species level, use zone diameter breakpoints S≥25, R<25 mm, with an ATU of 22-24 mm. For isolates with results inside the ATU: identify species, perform PCR for mecA/mecC or report resistant.
[E] For screening for methicillin resistance in S. pseudintermedius, S. intermedius, S. schleiferi and S. coagulans.
[E] For screening for methicillin resistance in S. pseudintermedius, S. intermedius, S. schleiferi and S. coagulans.
[C] Most staphylococci are penicillinase producers and some are methicillin resistant. Either mechanism renders them resistant to benzylpenicillin, phenoxymethylpenicillin, ampicillin, amoxicillin, piperacillin and ticarcillin. No currently available method can reliably detect penicillinase production in all species of staphylococci but methicillin resistance can be detected with cefoxitin as described. | [D] Ampicillin susceptible S. saprophyticus are mecA-negative and susceptible to ampicillin, amoxicillin and piperacillin (without or with a beta-lactamase inhibitor).
[1] Erythromycin can be used to screen for macrolide resistance in Streptococcus groups A, B, C and
[B] Place the erythromycin and clindamycin disks 12-16 mm apart (edge to edge) and look for antagonism (the D phenomenon) to detect inducible clindamycin resistance. | [2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant and consider adding this comment to the report: "Clindamycin may still be used for short-term therapy of less serious skin and soft tissue infections as constitutive resistance is unlikely to develop during such therapy". The clinical importance of inducible clindamycin resistance in combination treatment of severe S. pyogenes infections is not known.
[2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant and consider adding this comment to the report: "Clindamycin may still be used for short-term therapy of less serious skin and soft tissue infections as constitutive resistance is unlikely to develop during such therapy". The clinical importance of inducible clindamycin resistance in combination treatment of severe S. pyogenes infections is not known.
[1] Erythromycin can be used to screen for macrolide resistance in Streptococcus groups A, B, C and
[2] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturers' instructions for commercial systems. | [3] Isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] Daptomycin MICs must be determined in the presence of Ca (50 mg/L in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturers' instructions for commercial systems. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[A] Erythromycin can be used to screen for macrolide resistance in Streptococcus groups A, B, C and
[1] Erythromycin can be used to screen for macrolide resistance in Streptococcus groups A, B, C and
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[B] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[B] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[C]  | [C] Isolates categorised as screen negative can be reported susceptible to moxifloxacin and as "susceptible increased exposure" (I) to levofloxacin. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for Gram-positive organisms and nalidixic acid for H. influenzae and M. catarrhalis).
[2] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturers' instructions for commercial systems. | [3] Isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Erythromycin can be used to screen for macrolide resistance in Streptococcus groups A, B, C and
[4] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[4] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[B] Non-wild type isolates were not available when developing the disk diffusion method. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[3] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [2] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Isolates susceptible to linezolid can be reported susceptible to tedizolid. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] Isolates susceptible to linezolid can be reported susceptible to tedizolid. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[B] Non-wild type isolates were not available when developing the disk diffusion method. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturers' instructions for commercial systems. | [3] Isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturers' instructions for commercial systems. | [3] Isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[5] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L. | [3] The addition of a beta-lactamase inhibitor does not add clinical benefit.
[1] Erythromycin can be used to screen for macrolide resistance in Streptococcus pneumoniae. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[B] Place the erythromycin and clindamycin disks 12-16 mm apart (edge to edge) and look for antagonism (the D phenomenon) to detect inducible clindamycin resistance. | [2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant.
[2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant.
[1] Erythromycin can be used to screen for macrolide resistance in Streptococcus pneumoniae. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[A] Erythromycin can be used to screen for macrolide resistance in Streptococcus pneumoniae. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Erythromycin can be used to screen for macrolide resistance in Streptococcus pneumoniae. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[B]  | [B] Isolates categorised as screen negative can be reported susceptible to moxifloxacin and as "susceptible increased exposure" (I) to levofloxacin. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for Gram-positive organisms and nalidixic acid for H. influenzae and M. catarrhalis).
[C] For interpretation of the oxacillin disk screen, see flow chart below. | [1] The oxacillin 1 µg disk diffusion screening test or a benzylpenicillin MIC test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (oxacillin zone diameter ≥20 mm, or benzylpenicillin MIC ≤0.06 mg/L) all beta-lactam agents for which clinical breakpoints are available, including those with “Note” can be reported susceptible without further testing, except for cefaclor, which if reported, should be reported as “susceptible, increased exposure” (I). When the screen is positive (zone diameter <20 mm, or benzylpenicillin MIC >0.06 mg/L), see flow chart below.
[2] For breakpoints and dosing in pneumonia, see table of dosages.
[1] Erythromycin can be used to screen for macrolide resistance in Streptococcus pneumoniae. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[A] Non-wild typeisolates were not available when developing the disk diffusion method. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Non-wild typeisolates were not available when developing the disk diffusion method. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Place the erythromycin and clindamycin disks 12-16 mm apart (edge to edge) and look for antagonism (the D phenomenon) to detect inducible clindamycin resistance. | [1] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant.
[1] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant.
[A] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. See Note 1/A on penicillins.
[A] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. See Note 1/A on penicillins.
[A] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. See Note 1/A on penicillins.
[A] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. See Note 1/A on penicillins.
[1] For susceptibility testing purposes, the concentration of relebactam is fixed at 4 mg/L. | [2] The addition of a beta-lactamase inhibitor does not add clinical benefit.
[A] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. Isolates categorised as screen negative can be reported susceptible to beta-lactam agents for which clinical breakpoints are listed (including those with “Note”). Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. Isolates categorised as screen negative can be reported susceptible to beta-lactam agents for which clinical breakpoints are listed (including those with “Note”). Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[B] Non-wild type isolates were not available when developing the disk diffusion method. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[B] Non-wild type isolates were not available when developing the disk diffusion method. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Susceptibility to azithromycin (and erythromycin when azithromycin is not available) is inferred from the erythromycin disk diffusion test.
[A] Susceptibility to ciprofloxacin and levofloxacin can be inferred from the pefloxacin disk diffusion screening test.
[1/A] Susceptibility to azithromycin (and erythromycin when azithromycin is not available) is inferred from the erythromycin disk diffusion test.
[A] Susceptibility to ciprofloxacin and levofloxacin can be inferred from the pefloxacin disk diffusion screening test.
[A] Susceptibility to ciprofloxacin and levofloxacin can be inferred from the pefloxacin disk diffusion screening test.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1/A] Susceptibility to doxycycline (and tetracycline when doxycycline is not available) is inferred from the tetracycline disk diffusion test.
[1] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[2] The intrinsically low activity of imipenem against Morganella morganii, Proteus spp. and Providencia spp. requires the high exposure of imipenem.
[2] The intrinsically low activity of imipenem against Morganella morganii, Proteus spp. and Providencia spp. requires the high exposure of imipenem.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [D] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[3] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[3] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[1] The aztreonam breakpoints for Enterobacterales will detect clinically important resistance mechanisms (including ESBL). Some isolates that produce beta-lactamases are susceptible to aztreonam with these breakpoints and should be reported as tested, i.e. the presence or absence of an ESBL does not in itself influence the categorisation of susceptibility. ESBL detection and characterisation are recommended for public health and infection control purposes.
[1] The aztreonam breakpoints for Enterobacterales will detect clinically important resistance mechanisms (including ESBL). Some isolates that produce beta-lactamases are susceptible to aztreonam with these breakpoints and should be reported as tested, i.e. the presence or absence of an ESBL does not in itself influence the categorisation of susceptibility. ESBL detection and characterisation are recommended for public health and infection control purposes.
[2] In meningitis, where all fluoroquinolone resistance mechanisms must be excluded, either perform an MIC test, or infer susceptibility from the pefloxacin 5 µg screening test.
[3] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [2] Colistin MIC determination should be performed with broth microdilution. Quality control must be performed with both a susceptible QC strain (E. coli ATCC 25922 or P. aeruginosa ATCC 27853) and the colistin resistant E. coli NCTC 13846 (mcr-1 positive).
[5] For susceptibility testing purposes, the concentration of avibactam is fixed at 4 mg/L.
[6] See table of dosages for dosing for different indications.
[7] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L. | [6] See table of dosages for dosing for different indications.
[3] Broth microdilution MIC determination must be performed in iron-depleted Mueller-Hinton broth and specific reading instructions must be followed. For testing conditions and reading instructions, see https://www.eucast.org/eucastguidancedocuments/.
[4] The cefoxitin cut-off value (8 mg/L) has a high sensitivity but poor specificity for identification of AmpC-producing Enterobacterales as this agent is also affected by permeability alterations and some carbapenemases. Classical non-AmpC producers are wild type, whereas plasmid AmpC producers or chromosomal AmpC hyperproducers are non-wild type.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[3] For susceptibility testing purposes, the concentration of relebactam is fixed at 4 mg/L.
[4] For susceptibility testing purposes, the concentration of vaborbactam is fixed at 8 mg/L.
[3] Fluoroquinolone breakpoints are available for other agents.
[3] Fluoroquinolone breakpoints are available for other agents.
[A] Tests with a ciprofloxacin 5 µg disk will not reliably exclude all fluoroquinolone resistance mechanisms in Salmonella spp. Perform an MIC test, or infer susceptibility from the pefloxacin 5 µg screening test. | [B] In meningitis, where all fluoroquinolone resistance mechanisms must be excluded, either perform an MIC test, or infer susceptibility from the pefloxacin 5 µg screening test. | [C] The pefloxacin screening test can also be used to detect fluoroquinolone resistance mechanisms in other Enterobacterales such as E. coli, K. pneumoniae and Shigella spp.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for Gram-positive organisms and nalidixic acid for H. influenzae and M. catarrhalis).
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[7] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[7] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[5] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[A] There may be growth within the inhibition zone. The density of growth may vary from a fine haze to substantial growth (see pictures below). If any zone edge can be seen, ignore growth within the inhibition zone and read the zone diameter. | [1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[2] For information on how to use breakpoints in brackets, see hhttps://www.eucast.org/eucastguidancedocuments/. | [1] Colistin MIC determination should be performed with broth microdilution. Quality control must be performed with both a susceptible QC strain (E. coli ATCC 25922 or P. aeruginosa ATCC 27853) and the colistin resistant E. coli NCTC 13846 (mcr-1 positive).
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[2] The beta-lactamases produced by the organisms either do not modify the parent carbapenem or are not affected by the inhibitor. Therefore the addition of the beta-lactamase inhibitor does not add clinical benefit.
[1] For susceptibility testing purposes, the concentration of relebactam is fixed at 4 mg/L. | [2] The beta-lactamases produced by the organisms either do not modify the parent carbapenem or are not affected by the inhibitor. Therefore the addition of the beta-lactamase inhibitor does not add clinical benefit.
[3] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[3] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] Susceptibility can be inferred from the norfloxacin disk diffusion screening test. See Note
[1] Susceptibility can be inferred from ciprofloxacin susceptibility.
[C]  | [C] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance.
[A] Non-wild type isolates were not available when developing the disk diffusion method.
[A] Susceptibility can be inferred from the norfloxacin disk diffusion screening test. See Note
[1] Susceptibility can be inferred from ciprofloxacin susceptibility.
[C]  | [C] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance.
[A] Non-wild type isolates were not available when developing the disk diffusion method.
[A] Read the obvious zone edge and disregard haze or growth within the inhibition zone (see pictures below). | [1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[B]  | [B] Isolates categorised as screen negative can be reported "susceptible increased exposure" (I) to ciprofloxacin and levofloxacin. Isolates categorised as screen positive can be reported resistant to ciprofloxacin and levofloxacin.
[A] Non-wild type isolates were not available when developing the disk diffusion method.
[1] Aminopenicillins without beta-lactamase inhibitors are rarely active against Bacteroides spp. and EUCAST has refrained from setting breakpoints for ampicillin and amoxicillin without inhibitors.
[3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L. | [1] Aminopenicillins without beta-lactamase inhibitors are rarely active against Bacteroides spp. and EUCAST has refrained from setting breakpoints for ampicillin and amoxicillin without inhibitors.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [B] Examine zones carefully for colonies within zones. Colonies should be taken into account when reading.
[5] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[5] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] Aminopenicillins without beta-lactamase inhibitors are rarely active against Bacteroides spp. and EUCAST has refrained from setting breakpoints for ampicillin and amoxicillin without inhibitors.
[2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L. | [1] Aminopenicillins without beta-lactamase inhibitors are rarely active against Bacteroides spp. and EUCAST has refrained from setting breakpoints for ampicillin and amoxicillin without inhibitors.
[4] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[1] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] There may be growth within the inhibition zone. The density of growth may vary from a fine haze to substantial growth (see pictures below). If any zone edge can be seen, ignore growth within the inhibition zone and read the zone diameter. | [1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Isolates categorised as screen negative can be reported "susceptible increased exposure" (I) to doxycyline. Isolates categorised as screen positive can be reported resistant to doxycycline.
[A] Susceptibility to azithromycin and clarithromycin can be inferred from erythromycin.
[1] Susceptibility to azithromycin and clarithromycin can be inferred from erythromycin.
[A] Susceptibility to doxycycline can be inferred from tetracycline.
[1] Susceptibility to doxycycline can be inferred from tetracycline.
[A] Susceptibility to azithromycin and clarithromycin can be inferred from erythromycin.
[1] Susceptibility to azithromycin and clarithromycin can be inferred from erythromycin.
[A] Susceptibility to doxycycline can be inferred from tetracycline.
[1] Susceptibility to doxycycline can be inferred from tetracycline.
[1] The breakpoints are based on epidemiological cut-off values (ECOFFs) and apply to oral treatment of C. difficile infections. There are no conclusive clinical data regarding the relation between MICs and outcomes.
[1] The breakpoints are based on epidemiological cut-off values (ECOFFs) and apply to oral treatment of C. difficile infections. There are no conclusive clinical data regarding the relation between MICs and outcomes.
[1] Inducible clindamycin resistance may occur in Corynebacterium spp. This can be detected by antagonism of clindamycin activity by a macrolide agent. The clinical significance is unknown. There is currently no recommendation for testing.
[1] Inducible clindamycin resistance may occur in Corynebacterium spp. This can be detected by antagonism of clindamycin activity by a macrolide agent. The clinical significance is unknown. There is currently no recommendation for testing.
[A] Non-wild typeisolates were not available when developing the disk diffusion method.
[1] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported susceptible to amoxicillin. Isolates resistant to benzylpenicillin should be tested for susceptibility to amoxicillin or reported resistant.
[1] Wild-type C. ulcerans is less susceptible to clindamycin.
[1] Wild-type C. ulcerans is less susceptible to clindamycin.
[A] Susceptibility to cefotaxime can be inferred from benzylpenicillin.
[1] Susceptibility to cefotaxime can be inferred from benzylpenicillin.
[1] Susceptibility to doxycycline can be inferred from tetracycline.
[A] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported susceptible to meropenem. Isolates resistant to benzylpenicillin should be tested for susceptibility to meropenem or reported resistant.
[1] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported susceptible to meropenem. Isolates resistant to benzylpenicillin should be tested for susceptibility to meropenem or reported resistant.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported susceptible to amoxicillin. Isolates resistant to benzylpenicillin should be tested for susceptibility to amoxicillin or reported resistant.
[A] Susceptibility to cefotaxime can be inferred from benzylpenicillin.
[1] Susceptibility to cefotaxime can be inferred from benzylpenicillin.
[1] Susceptibility to doxycycline can be inferred from tetracycline.
[A] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported susceptible to meropenem. Isolates resistant to benzylpenicillin should be tested for susceptibility to meropenem or reported resistant.
[1] Isolates "susceptible, increased exposure” (I) to benzylpenicillin can be reported susceptible to meropenem. Isolates resistant to benzylpenicillin should be tested for susceptibility to meropenem or reported resistant.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[D] Examine zones carefully for colonies within zones. Colonies should be taken into account when reading.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [C] Susceptibility to ceftriaxone can be inferred from the cefotaxime disk diffusion test.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [C] Susceptibility to ceftriaxone can be inferred from the cefotaxime disk diffusion test.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[F] Ignore isolated colonies within the inhibition zone.
[6] Agar dilution is the reference method for mecillinam MIC determination.
[A] For other Enterobacterales, the activity of tigecycline varies from insufficient inSerratia spp., Proteus spp., Morganella morganii and Providencia spp. to variable in other species. For more information, see https://www.eucast.org/eucastguidancedocuments/. | [B] Zone diameter breakpoints validated for E. coli only. For C. koseri, use an MIC method.
[2] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [3] For other Enterobacterales, the activity of tigecycline varies from insufficient inSerratia spp., Proteus spp., Morganella morganii and Providencia spp. to variable in other species. For more information, see https://www.eucast.org/eucastguidancedocuments/.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[C] Examine zones carefully for colonies within zones. Colonies should be taken into account when reading.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [4] For susceptibility testing purposes, the concentration of  tazobactam is fixed at 4 mg/L.
[F] Ignore isolated colonies within the inhibition zone.
[6] Agar dilution is the reference method for mecillinam MIC determination.
[2] In E. faecalis, susceptibility to ampicillin, amoxicillin and piperacillin (with and without beta-lactamase inhibitor) is the expected phenotype, while in E. faecium, resistance is common. Isolates resistant to ampicillin can be reported resistant to ampicillin, amoxicillin and piperacillin (with or without inhibitor). For E. faecalis that test resistant to ampicillin with disk diffusion, confirm with an MIC test. | [4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L. | [1] Aminopenicillin breakpoints in enterococci are based on intravenous administration. For oral administration the breakpoints are relevant for urinary tract infections only.
[A] In E. faecalis, susceptibility to ampicillin, amoxicillin and piperacillin (with and without beta-lactamase inhibitor) is the expected phenotype, while in E. faecium, resistance is common. Isolates resistant to ampicillin can be reported resistant to ampicillin, amoxicillin and piperacillin (with or without inhibitor). For E. faecalis that test resistant to ampicillin with disk diffusion, confirm with an MIC test. | [1] Aminopenicillin breakpoints in enterococci are based on intravenous administration. For oral administration the breakpoints are relevant for urinary tract infections only.
[2] In E. faecalis, susceptibility to ampicillin, amoxicillin and piperacillin (with and without beta-lactamase inhibitor) is the expected phenotype, while in E. faecium, resistance is common. Isolates resistant to ampicillin can be reported resistant to ampicillin, amoxicillin and piperacillin (with or without inhibitor). For E. faecalis that test resistant to ampicillin with disk diffusion, confirm with an MIC test. | [1] Aminopenicillin breakpoints in enterococci are based on intravenous administration. For oral administration the breakpoints are relevant for urinary tract infections only.
[2] In E. faecalis, susceptibility to ampicillin, amoxicillin and piperacillin (with and without beta-lactamase inhibitor) is the expected phenotype, while in E. faecium, resistance is common. Isolates resistant to ampicillin can be reported resistant to ampicillin, amoxicillin and piperacillin (with or without inhibitor). For E. faecalis that test resistant to ampicillin with disk diffusion, confirm with an MIC test. | [1] Aminopenicillin breakpoints in enterococci are based on intravenous administration. For oral administration the breakpoints are relevant for urinary tract infections only.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[C]  | [C] Susceptibility to ciprofloxacin and levofloxacin can be inferred from the norfloxacin disk diffusion screening test. For moxifloxacin, see comment 1/B.
[2] In E. faecalis, susceptibility to ampicillin, amoxicillin and piperacillin (with and without beta-lactamase inhibitor) is the expected phenotype, while in E. faecium, resistance is common. Isolates resistant to ampicillin can be reported resistant to ampicillin, amoxicillin and piperacillin (with or without inhibitor). For E. faecalis that test resistant to ampicillin with disk diffusion, confirm with an MIC test. | [3] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L. | [1] Aminopenicillin breakpoints in enterococci are based on intravenous administration. For oral administration the breakpoints are relevant for urinary tract infections only.
[A] Vancomycin susceptible enterococci exhibit sharp zone edges and do not exhibit colonies in the inhibition zone. Examine zone edges with transmitted light (plate held up to light). If the zone edge is fuzzy, colonies grow within the zone  or if you are uncertain, then perform confirmatory testing with PCR or report resistant (see pictures below) even if the zone diameter is ≥ 12 mm. Isolates must not be reported susceptible before 24 h incubation.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Isolates susceptible to cefadroxil and/or cefalexin can be reported "susceptible, increased exposure” (I) to cefazolin.
[2] Isolates susceptible to cefadroxil and/or cefalexin can be reported "susceptible, increased exposure” (I) to cefazolin.
[E] Ignore isolated colonies within the inhibition zone (see pictures below).
[5] Agar dilution is the reference method for fosfomycin. MICs must be determined in the presence of glucose-6-phosphate (25 mg/L in the medium). Follow the manufacturers' instructions for commercial systems.
[F] Ignore isolated colonies within the inhibition zone.
[6] Agar dilution is the reference method for mecillinam MIC determination.
[F] Ignore isolated colonies within the inhibition zone.
[A] For other Enterobacterales, the activity of tigecycline varies from insufficient inSerratia spp., Proteus spp., Morganella morganii and Providencia spp. to variable in other species. For more information, see https://www.eucast.org/eucastguidancedocuments/. | [B] Zone diameter breakpoints validated for E. coli only. For C. koseri, use an MIC method.
[2] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [3] For other Enterobacterales, the activity of tigecycline varies from insufficient inSerratia spp., Proteus spp., Morganella morganii and Providencia spp. to variable in other species. For more information, see https://www.eucast.org/eucastguidancedocuments/.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[C] Examine zones carefully for colonies within zones. Colonies should be taken into account when reading.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents. | [4] For susceptibility testing purposes, the concentration of  tazobactam is fixed at 4 mg/L.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[5] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[5] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below. | [2] Beta-lactamase positive isolates can be reported resistant to ampicillin, amoxicillin and piperacillin without inhibitors. Tests based on a chromogenic cephalosporin can be used to detect the beta-lactamase.
[2] Beta-lactamase positive isolates can be reported resistant to ampicillin, amoxicillin and piperacillin without inhibitors. Tests based on a chromogenic cephalosporin can be used to detect the beta-lactamase.
[2] Beta-lactamase positive isolates can be reported resistant to ampicillin, amoxicillin and piperacillin without inhibitors. Tests based on a chromogenic cephalosporin can be used to detect the beta-lactamase.
[2] Beta-lactamase positive isolates can be reported resistant to ampicillin, amoxicillin and piperacillin without inhibitors. Tests based on a chromogenic cephalosporin can be used to detect the beta-lactamase.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[1] For chloramphenicol treatment in meningitis, see table of dosages.
[1] For chloramphenicol treatment in meningitis, see table of dosages.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below. | [2] See table of dosages for dosing for different indications.
[2] See table of dosages for dosing for different indications.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all carbapenems for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all carbapenems for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all carbapenems for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all carbapenems for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[C]  | [C] Isolates categorised as screen negative can be reported susceptible to ciprofloxacin, levofloxacin, moxifloxacin and ofloxacin. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for Gram-positive organisms and nalidixic acid for H. influenzae and M. catarrhalis).
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[1/A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[3] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L. | [4] Susceptibility can be inferred from amoxicillin-clavulanic acid iv.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (zone diameter ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (zone diameter <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[6] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[2] Susceptibility can be inferred from benzylpenicillin susceptibility.
[2] Susceptibility can be inferred from benzylpenicillin susceptibility.
[1] Susceptibility can be inferred from erythromycin susceptibility.
[1] Susceptibility can be inferred from erythromycin susceptibility.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline. Isolates categorised as resistant should be tested for susceptibility to doxycycline or reported resistant.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Isolates susceptible to cefadroxil and/or cefalexin can be reported "susceptible, increased exposure” (I) to cefazolin.
[2] Isolates susceptible to cefadroxil and/or cefalexin can be reported "susceptible, increased exposure” (I) to cefazolin.
[F] Ignore isolated colonies within the inhibition zone.
[6] Agar dilution is the reference method for mecillinam MIC determination.
[F] Ignore isolated colonies within the inhibition zone.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[1] Erythromycin can be used to screen for macrolide resistance in Moraxella catarrhalis. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[1] Erythromycin can be used to screen for macrolide resistance in Moraxella catarrhalis. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[A] Erythromycin can be used to screen for macrolide resistance in Moraxella catarrhalis. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[B]  | [B] Isolates categorised as screen negative can be reported susceptible to ciprofloxacin, levofloxacin, moxifloxacin and ofloxacin. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for Gram-positive organisms and nalidixic acid for H. influenzae and M. catarrhalis).
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[1] Erythromycin can be used to screen for macrolide resistance in Moraxella catarrhalis. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L. | [3] Susceptibility can be inferred from amoxicillin-clavulanic acid.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[1] Breakpoints were determined on MICs performed on Middlebrook 7H11/7H10 medium. The comparability of tests performed by other media has not been established. There is ongoing work to review breakpoints using the EUCAST reference method (described above).
[1] Always test for beta-lactamase (tests based on a chromogenic cephalosporin can be used). If beta-lactamase positive, report resistant to ampicillin and amoxicillin. If beta-lactamase negative, determine the MIC of benzylpenicillin. Infer the susceptibility to ampicillin and amoxicillin from the benzylpenicillin MIC (do not report benzylpenicillin susceptibility).
[1] For chloramphenicol treatment in meningitis, see table of dosages.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory. | [2] Breakpoints for serious N. meningitidis systemic infections (meningitis with or without septicemia) have been determined for meropenem only.
[1] Tetracycline can be used to predict susceptibility to minocycline for prophylaxis against N. meningitidis infections.
[1] Tetracycline can be used to predict susceptibility to minocycline for prophylaxis against N. meningitidis infections.
[F] Ignore isolated colonies within the inhibition zone.
[6] Agar dilution is the reference method for mecillinam MIC determination.
[F] Ignore isolated colonies within the inhibition zone.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[C] Examine zones carefully for colonies within zones. Colonies should be taken into account when reading.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[1] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] Isolates susceptible to benzylpenicillin can be reported susceptible to all beta-lactam agents with breakpoints (including those with Note) without further testing. Isolates resistant to benzylpenicillin should be tested for susceptibility to individual agents.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[2] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [1] Colistin MIC determination should be performed with broth microdilution. Quality control must be performed with both a susceptible QC strain (E. coli ATCC 25922 or P. aeruginosa ATCC 27853) and the colistin resistant E. coli NCTC 13846 (mcr-1 positive).
[2] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[2] For susceptibility testing purposes, the concentration of avibactam is fixed at 4 mg/L.
[3] See table of dosages for dosing for different indications.
[4] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L. | [3] See table of dosages for dosing for different indications.
[1] Broth microdilution MIC determination must be performed in iron-depleted Mueller-Hinton broth and specific reading instructions must be followed. For testing conditions and reading instructions, see https://www.eucast.org/eucastguidancedocuments/.
[1] For susceptibility testing purposes, the concentration of relebactam is fixed at 4 mg/L.
[2] For susceptibility testing purposes, the concentration of vaborbactam is fixed at 8 mg/L.
[1] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note B.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note B.
[B] Isolates categorised as screen negative can be reported susceptible to ciprofloxacin and levofloxacin. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Susceptibility to doxycycline can be inferred from the tetracycline disk diffusion screening test.
[1] There is clinical evidence for ciprofloxacin to indicate a poor response in systemic infections caused by Salmonella spp. with low-level ciprofloxacin resistance (MIC >0.06 mg/L). The available data relate mainly to Salmonella Typhi but there are also case reports of poor response with other Salmonella species.
[A] There may be growth within the inhibition zone. The density of growth may vary from a fine haze to substantial growth (see pictures below). If any zone edge can be seen, ignore growth within the inhibition zone and read the zone diameter. | [1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Erythromycin can be used to screen for macrolide resistance in staphylococci. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[B] Place the erythromycin and clindamycin disks 12-20 mm apart (edge to edge) and look for antagonism (the D phenomenon) to detect inducible clindamycin resistance. | [2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant and consider adding this comment to the report: "Clindamycin may still be used for short-term therapy of less serious skin and soft tissue infections as constitutive resistance is unlikely to develop during such therapy".
[2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant and consider adding this comment to the report: "Clindamycin may still be used for short-term therapy of less serious skin and soft tissue infections as constitutive resistance is unlikely to develop during such therapy".
[1] Erythromycin can be used to screen for macrolide resistance in staphylococci. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[3] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturers' instructions for commercial systems. | [4] S. aureus isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin.
[2] Daptomycin MICs must be determined in the presence of Ca (50 mg/L in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturers' instructions for commercial systems. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[A] Erythromycin can be used to screen for macrolide resistance in staphylococci. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Erythromycin can be used to screen for macrolide resistance in staphylococci. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[4] Agar dilution is the reference method for fosfomycin. MICs must be determined in the presence of glucose-6-phosphate (25 mg/L in the medium). | [3] Breakpoints for fosfomycin iv are currently under review.
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[C]  | [C] Isolates categorised as screen negative can be reported susceptible to moxifloxacin and "susceptible increased exposure" (I) to ciprofloxacin and levofloxacin. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Erythromycin can be used to screen for macrolide resistance in staphylococci. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[5] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[5] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[2] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[3] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [2] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Isolates susceptible to linezolid can be reported susceptible to tedizolid.
[1] Isolates susceptible to linezolid can be reported susceptible to tedizolid.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [2] Resistance to amikacin is most reliably determined by testing with kanamycin (MIC >8 mg/L). The corresponding zone diameter for the kanamycin 30 µg disk is R<18 mm for S. aureus and R<22 mm for coagulase-negative staphylococci.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [2] Resistance to amikacin is most reliably determined by testing with kanamycin (MIC >8 mg/L). The corresponding zone diameter for the kanamycin 30 µg disk is R<18 mm for S. aureus and R<22 mm for coagulase-negative staphylococci.
[F] Methicillin-susceptible isolates can be reported susceptible to ceftobiprole without further testing.
[8] Methicillin-susceptible isolates can be reported susceptible to ceftobiprole without further testing.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[D] Methicillin-susceptible isolates can be reported susceptible to ceftaroline without further testing.
[D] Methicillin-susceptible isolates can be reported susceptible to ceftaroline without further testing.
[6] Methicillin-susceptible isolates can be reported susceptible to ceftaroline without further testing.
[6] Methicillin-susceptible isolates can be reported susceptible to ceftaroline without further testing.
[B] For MRSA that test susceptible with disk diffusion, the results should be confirmed with an MIC test.
[A] Susceptibility of staphylococci to cephalosporins is inferred from the cefoxitin susceptibility except for cefixime, ceftazidime, ceftazidime-avibactam, ceftibuten and ceftolozane-tazobactam, which do not have breakpoints and should not be used for staphylococcal infections. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. If cefotaxime and ceftriaxone are reported for methicillin-susceptible staphylococci, these should be reported “Susceptible, increased exposure” (I). Some methicillin-resistant S. aureus are susceptible to ceftaroline and ceftobiprole, see Notes 5/D and 7/F. | [B] If coagulase-negative staphylococci are not identified to species level, use zone diameter breakpoints S≥25, R<25 mm, with an ATU of 22-24 mm. For isolates with results inside the ATU: identify species, perform PCR for mecA/mecC or report resistant.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[2] Breakpoints for nasal decontamination S ≤1, R >256 mg/L (S ≥30, R <18 mm for the mupirocin 200 µg disk). Isolates in the I category are associated with short term suppression (useful preoperatively) but, unlike fully susceptible isolates, long term eradication rates are low.
ND = No ECOFF available.
[2] Breakpoints for nasal decontamination S ≤1, R >256 mg/L (S ≥30, R <18 mm for the mupirocin 200 µg disk). Isolates in the I category are associated with short term suppression (useful preoperatively) but, unlike fully susceptible isolates, long term eradication rates are low.
ND = No ECOFF available.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for Gram-positive organisms and nalidixic acid for H. influenzae and M. catarrhalis).
[3] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturers' instructions for commercial systems. | [4] S. aureus isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin.
[A] Most S. aureus are penicillinase producers and some are methicillin resistant. Either mechanism renders them resistant to benzylpenicillin, phenoxymethylpenicillin, ampicillin, amoxicillin, piperacillin and ticarcillin. Isolates that test susceptible to benzylpenicillin and cefoxitin can be reported susceptible to all penicillins. Isolatesthat test resistant to benzylpenicillin but susceptible to cefoxitin are susceptible to β-lactam β-lactamase inhibitor combinations, the isoxazolylpenicillins (oxacillin, cloxacillin, dicloxacillin and flucloxacillin) and nafcillin. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. Isolates that test resistant to cefoxitin are resistant to all penicillins. | [B] For S. aureus, disk diffusion is more reliable than MIC determination for detection of penicillinase producers, provided the zone diameter is measured AND the zone edge for isolates with zone diameters ≥26 mm is closely inspected (see pictures below). Examine the zone edge with transmitted light (plate held up to light). If the zone diameter is <26 mm, then report resistant. If the zone diameter is ≥26 mm AND the zone edge is sharp (no reduction of growth towards zone edge, like a "cliff"), then report resistant. If not sharp (reduction of growth towards zone edge,  like a "beach"), then report susceptible and if uncertain, then report resistant. Chromogenic cephalosporin-based beta-lactamase tests do not reliably detect staphylococcal penicillinase.
[1] Most S. aureus are penicillinase producers and some are methicillin resistant. Either mechanism renders them resistant to benzylpenicillin, phenoxymethylpenicillin, ampicillin, amoxicillin, piperacillin and ticarcillin. Isolates that test susceptible to benzylpenicillin and cefoxitin can be reported susceptible to all penicillins. Isolatesthat test resistant to benzylpenicillin but susceptible to cefoxitin are susceptible to β-lactam β-lactamase inhibitor combinations, the isoxazolylpenicillins (oxacillin, cloxacillin, dicloxacillin and flucloxacillin) and nafcillin. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. Isolates that test resistant to cefoxitin are resistant to all penicillins.
[3] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturers' instructions for commercial systems. | [5] MRSA isolates susceptible to vancomycin can be reported susceptible to telavancin.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[E] For screening for methicillin resistance in S. pseudintermedius, S. schleiferi and S. coagulans.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [2] Resistance to amikacin is most reliably determined by testing with kanamycin (MIC >8 mg/L). The corresponding zone diameter for the kanamycin 30 µg disk is R<18 mm for S. aureus and R<22 mm for coagulase-negative staphylococci.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [2] Resistance to amikacin is most reliably determined by testing with kanamycin (MIC >8 mg/L). The corresponding zone diameter for the kanamycin 30 µg disk is R<18 mm for S. aureus and R<22 mm for coagulase-negative staphylococci.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Susceptibility of staphylococci to cephalosporins is inferred from the cefoxitin susceptibility except for cefixime, ceftazidime, ceftazidime-avibactam, ceftibuten and ceftolozane-tazobactam, which do not have breakpoints and should not be used for staphylococcal infections. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. If cefotaxime and ceftriaxone are reported for methicillin-susceptible staphylococci, these should be reported “Susceptible, increased exposure” (I). Some methicillin-resistant S. aureus are susceptible to ceftaroline and ceftobiprole, see Notes 5/D and 7/F. | [B] If coagulase-negative staphylococci are not identified to species level, use zone diameter breakpoints S≥25, R<25 mm, with an ATU of 22-24 mm. For isolates with results inside the ATU: identify species, perform PCR for mecA/mecC or report resistant.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] Susceptibility of staphylococci to cephalosporins is inferred from the cefoxitin susceptibility except for cefixime, ceftazidime, ceftazidime-avibactam, ceftibuten and ceftolozane-tazobactam, which do not have breakpoints and should not be used for staphylococcal infections. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. If cefotaxime and ceftriaxone are reported for methicillin-susceptible staphylococci, these should be reported “Susceptible, increased exposure” (I). Some methicillin-resistant S. aureus are susceptible to ceftaroline and ceftobiprole, see Notes 5/D and 7/F. | [B] If coagulase-negative staphylococci are not identified to species level, use zone diameter breakpoints S≥25, R<25 mm, with an ATU of 22-24 mm. For isolates with results inside the ATU: identify species, perform PCR for mecA/mecC or report resistant.
[A] Susceptibility of staphylococci to cephalosporins is inferred from the cefoxitin susceptibility except for cefixime, ceftazidime, ceftazidime-avibactam, ceftibuten and ceftolozane-tazobactam, which do not have breakpoints and should not be used for staphylococcal infections. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. If cefotaxime and ceftriaxone are reported for methicillin-susceptible staphylococci, these should be reported “Susceptible, increased exposure” (I). Some methicillin-resistant S. aureus are susceptible to ceftaroline and ceftobiprole, see Notes 5/D and 7/F. | [B] If coagulase-negative staphylococci are not identified to species level, use zone diameter breakpoints S≥25, R<25 mm, with an ATU of 22-24 mm. For isolates with results inside the ATU: identify species, perform PCR for mecA/mecC or report resistant.
[E] For screening for methicillin resistance in S. pseudintermedius, S. schleiferi and S. coagulans.
[E] For screening for methicillin resistance in S. pseudintermedius, S. schleiferi and S. coagulans.
[C] Most staphylococci are penicillinase producers and some are methicillin resistant. Either mechanism renders them resistant to benzylpenicillin, phenoxymethylpenicillin, ampicillin, amoxicillin, piperacillin and ticarcillin. No currently available method can reliably detect penicillinase production in all species of staphylococci but methicillin resistance can be detected with cefoxitin as described. | [D] Ampicillin susceptible S. saprophyticus are mecA-negative and susceptible to ampicillin, amoxicillin and piperacillin (without or with a beta-lactamase inhibitor).
[1] Erythromycin can be used to screen for macrolide resistance in Streptococcus groups A, B, C and
[B] Place the erythromycin and clindamycin disks 12-16 mm apart (edge to edge) and look for antagonism (the D phenomenon) to detect inducible clindamycin resistance. | [2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant and consider adding this comment to the report: "Clindamycin may still be used for short-term therapy of less serious skin and soft tissue infections as constitutive resistance is unlikely to develop during such therapy". The clinical importance of inducible clindamycin resistance in combination treatment of severe S. pyogenes infections is not known.
[2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant and consider adding this comment to the report: "Clindamycin may still be used for short-term therapy of less serious skin and soft tissue infections as constitutive resistance is unlikely to develop during such therapy". The clinical importance of inducible clindamycin resistance in combination treatment of severe S. pyogenes infections is not known.
[1] Erythromycin can be used to screen for macrolide resistance in Streptococcus groups A, B, C and
[2] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturer's instructions for commercial systems. | [3] Isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] Daptomycin MICs must be determined in the presence of Ca (50 mg/L in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturer's instructions for commercial systems. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[A] Erythromycin can be used to screen for macrolide resistance in Streptococcus groups A, B, C and
[1] Erythromycin can be used to screen for macrolide resistance in Streptococcus groups A, B, C and
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[B] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[B] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[C]  | [C] Isolates categorised as screen negative can be reported susceptible to moxifloxacin and as "susceptible increased exposure" (I) to levofloxacin. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for Gram-positive organisms and nalidixic acid for H. influenzae and M. catarrhalis).
[2] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturer's instructions for commercial systems. | [3] Isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Erythromycin can be used to screen for macrolide resistance in Streptococcus groups A, B, C and
[4] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[4] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[B] Non-wild type isolates were not available when developing the disk diffusion method. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[3] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [2] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Isolates susceptible to linezolid can be reported susceptible to tedizolid. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] Isolates susceptible to linezolid can be reported susceptible to tedizolid. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[B] Non-wild type isolates were not available when developing the disk diffusion method. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturer's instructions for commercial systems. | [3] Isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturer's instructions for commercial systems. | [3] Isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[3] Breakpoints for trimethoprim are currently under review.
[5] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L. | [3] The addition of a beta-lactamase inhibitor does not add clinical benefit.
[1] Erythromycin can be used to screen for macrolide resistance in Streptococcus pneumoniae. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[B] Place the erythromycin and clindamycin disks 12-16 mm apart (edge to edge) and look for antagonism (the D phenomenon) to detect inducible clindamycin resistance. | [2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant.
[2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant.
[1] Erythromycin can be used to screen for macrolide resistance in Streptococcus pneumoniae. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[A] Erythromycin can be used to screen for macrolide resistance in Streptococcus pneumoniae. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Erythromycin can be used to screen for macrolide resistance in Streptococcus pneumoniae. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[B]  | [B] Isolates categorised as screen negative can be reported susceptible to moxifloxacin and as "susceptible increased exposure" (I) to levofloxacin. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for Gram-positive organisms and nalidixic acid for H. influenzae and M. catarrhalis).
[C] For interpretation of the oxacillin disk screen, see flow chart below. | [1] The oxacillin 1 µg disk diffusion screening test or a benzylpenicillin MIC test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (oxacillin zone diameter ≥20 mm, or benzylpenicillin MIC ≤0.06 mg/L) all beta-lactam agents for which clinical breakpoints are available, including those with “Note” can be reported susceptible without further testing, except for cefaclor, which if reported, should be reported as “susceptible, increased exposure” (I). When the screen is positive (zone diameter <20 mm, or benzylpenicillin MIC >0.06 mg/L), see flow chart below.
[2] For breakpoints and dosing in pneumonia, see table of dosages.
[1] Erythromycin can be used to screen for macrolide resistance in Streptococcus pneumoniae. Isolates categorised as susceptible can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant should be tested for susceptibility to individual agents or reported resistant.
[A] Non-wild typeisolates were not available when developing the disk diffusion method. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Non-wild typeisolates were not available when developing the disk diffusion method. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Place the erythromycin and clindamycin disks 12-16 mm apart (edge to edge) and look for antagonism (the D phenomenon) to detect inducible clindamycin resistance. | [1] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant.
[1] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant.
[A] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. See Note 1/A on penicillins.
[A] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. See Note 1/A on penicillins.
[A] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. See Note 1/A on penicillins.
[A] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. See Note 1/A on penicillins.
[1] For susceptibility testing purposes, the concentration of relebactam is fixed at 4 mg/L. | [2] The addition of a beta-lactamase inhibitor does not add clinical benefit.
[A] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. Isolates categorised as screen negative can be reported susceptible to beta-lactam agents for which clinical breakpoints are listed (including those with “Note”). Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. Isolates categorised as screen negative can be reported susceptible to beta-lactam agents for which clinical breakpoints are listed (including those with “Note”). Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[B] Non-wild type isolates were not available when developing the disk diffusion method. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[B] Non-wild type isolates were not available when developing the disk diffusion method. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Susceptibility to azithromycin (and erythromycin when azithromycin is not available) is inferred from the erythromycin disk diffusion test.
[A] Susceptibility to ciprofloxacin and levofloxacin can be inferred from the pefloxacin disk diffusion screening test.
[1/A] Susceptibility to azithromycin (and erythromycin when azithromycin is not available) is inferred from the erythromycin disk diffusion test.
[A] Susceptibility to ciprofloxacin and levofloxacin can be inferred from the pefloxacin disk diffusion screening test.
[A] Susceptibility to ciprofloxacin and levofloxacin can be inferred from the pefloxacin disk diffusion screening test.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1/A] Susceptibility to doxycycline (and tetracycline when doxycycline is not available) is inferred from the tetracycline disk diffusion test.
[1] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[2] The intrinsically low activity of imipenem against Morganella morganii, Proteus spp. and Providencia spp. requires the high exposure of imipenem.
[2] The intrinsically low activity of imipenem against Morganella morganii, Proteus spp. and Providencia spp. requires the high exposure of imipenem.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [D] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[3] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[3] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[1] The aztreonam breakpoints for Enterobacterales will detect clinically important resistance mechanisms (including ESBL). Some isolates that produce beta-lactamases are susceptible to aztreonam with these breakpoints and should be reported as tested, i.e. the presence or absence of an ESBL does not in itself influence the categorisation of susceptibility. ESBL detection and characterisation are recommended for public health and infection control purposes.
[1] The aztreonam breakpoints for Enterobacterales will detect clinically important resistance mechanisms (including ESBL). Some isolates that produce beta-lactamases are susceptible to aztreonam with these breakpoints and should be reported as tested, i.e. the presence or absence of an ESBL does not in itself influence the categorisation of susceptibility. ESBL detection and characterisation are recommended for public health and infection control purposes.
[2] In meningitis, where low-level ciprofloxacin resistance must be excluded, either perform an MIC test, or infer susceptibility from the pefloxacin 5 µg screening test.
[3] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [2] Colistin MIC determination should be performed with broth microdilution. Quality control must be performed with both a susceptible QC strain (E. coli ATCC 25922 or P. aeruginosa ATCC 27853) and the colistin resistant E. coli NCTC 13846 (mcr-1 positive).
[5] For susceptibility testing purposes, the concentration of avibactam is fixed at 4 mg/L.
[6] See table of dosages for dosing for different indications.
[7] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L. | [6] See table of dosages for dosing for different indications.
[3] Broth microdilution MIC determination must be performed in iron-depleted Mueller-Hinton broth and specific reading instructions must be followed. For testing conditions and reading instructions, see https://www.eucast.org/eucastguidancedocuments/.
[D] Zone diameter breakpoints apply to E. coli only. For other Enterobacterales, use an MIC method. | [E] Ignore isolated colonies within the inhibition zone (see pictures below). | [4] Breakpoints for fosfomycin iv are currently under review.
[5] Agar dilution is the reference method for fosfomycin. MICs must be determined in the presence of glucose-6-phosphate (25 mg/L in the medium). Follow the manufacturers' instructions for commercial systems. | [4] Breakpoints for fosfomycin iv are currently under review.
[4] The cefoxitin cut-off value (8 mg/L) has a high sensitivity but poor specificity for identification of AmpC-producing Enterobacterales as this agent is also affected by permeability alterations and some carbapenemases. Classical non-AmpC producers are wild type, whereas plasmid AmpC producers or chromosomal AmpC hyperproducers are non-wild type.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[3] For susceptibility testing purposes, the concentration of relebactam is fixed at 4 mg/L.
[4] For susceptibility testing purposes, the concentration of vaborbactam is fixed at 8 mg/L.
[A] Tests with a ciprofloxacin 5 µg disk will not reliably detect low-level resistance in Salmonella spp. Perform an MIC test, or infer susceptibility from the pefloxacin 5 µg screening test. | [B] In meningitis, where low-level ciprofloxacin resistance must be excluded, either perform an MIC test, or infer susceptibility from the pefloxacin 5 µg screening test. | [C] The pefloxacin screening test can also be used to detect fluoroquinolone resistance mechanisms in other Enterobacterales such as E. coli, K. pneumoniae and Shigella spp.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for Gram-positive organisms and nalidixic acid for H. influenzae and M. catarrhalis).
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L. | [1] For information on how to implement the new aminopenicillin breakpoints, see https://www.eucast.org/eucastguidancedocuments/.
[6] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[6] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[5] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[A] There may be growth within the inhibition zone. The density of growth may vary from a fine haze to substantial growth (see pictures below). If any zone edge can be seen, ignore growth within the inhibition zone and read the zone diameter. | [1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[2] For information on how to use breakpoints in brackets, see hhttps://www.eucast.org/eucastguidancedocuments/. | [1] Colistin MIC determination should be performed with broth microdilution. Quality control must be performed with both a susceptible QC strain (E. coli ATCC 25922 or P. aeruginosa ATCC 27853) and the colistin resistant E. coli NCTC 13846 (mcr-1 positive).
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[2] The beta-lactamases produced by the organisms either do not modify the parent carbapenem or are not affected by the inhibitor. Therefore the addition of the beta-lactamase inhibitor does not add clinical benefit.
[1] For susceptibility testing purposes, the concentration of relebactam is fixed at 4 mg/L. | [2] The beta-lactamases produced by the organisms either do not modify the parent carbapenem or are not affected by the inhibitor. Therefore the addition of the beta-lactamase inhibitor does not add clinical benefit.
[3] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[3] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] Susceptibility can be inferred from the norfloxacin disk diffusion screening test. See Note
[1] Susceptibility can be inferred from ciprofloxacin susceptibility.
[C]  | [C] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance.
[A] Non-wild type isolates were not available when developing the disk diffusion method.
[A] Susceptibility can be inferred from the norfloxacin disk diffusion screening test. See Note
[1] Susceptibility can be inferred from ciprofloxacin susceptibility.
[C]  | [C] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance.
[A] Non-wild type isolates were not available when developing the disk diffusion method.
[A] Read the obvious zone edge and disregard haze or growth within the inhibition zone (see pictures below). | [1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[B]  | [B] Isolates categorised as screen negative can be reported "susceptible increased exposure" (I) to ciprofloxacin and levofloxacin. Isolates categorised as screen positive can be reported resistant to ciprofloxacin and levofloxacin.
[A] Non-wild type isolates were not available when developing the disk diffusion method.
[B] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [C] Examine zones carefully for colonies within zones. Colonies should be taken into account when reading.
[3] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] The meropenem zone diameter breakpoint will detect all cfiA gene mediated carbapenem resistance in Bacteroides fragilis. Some isolates with an MIC of 1 mg/L may harbour the cfiA gene.
[2] The meropenem zone diameter breakpoint will detect all cfiA gene mediated carbapenem resistance in Bacteroides fragilis. Some isolates with an MIC of 1 mg/L may harbour the cfiA gene.
[1] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[1] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] There may be growth within the inhibition zone. The density of growth may vary from a fine haze to substantial growth (see pictures below). If any zone edge can be seen, ignore growth within the inhibition zone and read the zone diameter. | [1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Isolates categorised as screen negative can be reported "susceptible increased exposure" (I) to doxycyline. Isolates categorised as screen positive can be reported resistant to doxycycline.
[A] Erythromycin can be used to determine susceptibility to azithromycin and clarithromycin.
[1] Erythromycin can be used to determine susceptibility to azithromycin and clarithromycin.
[A] Tetracycline can be used to determine susceptibility to doxycycline.
[1] Tetracycline can be used to determine susceptibility to doxycycline.
[A] Erythromycin can be used to determine susceptibility to azithromycin and clarithromycin.
[1] Erythromycin can be used to determine susceptibility to azithromycin and clarithromycin.
[A] Tetracycline can be used to determine susceptibility to doxycycline.
[1] Tetracycline can be used to determine susceptibility to doxycycline.
[1] The breakpoints are based on epidemiological cut-off values (ECOFFs) and apply to oral treatment of C. difficile infections. There are no conclusive clinical data regarding the relation between MICs and outcomes.
[1] The breakpoints are based on epidemiological cut-off values (ECOFFs) and apply to oral treatment of C. difficile infections. There are no conclusive clinical data regarding the relation between MICs and outcomes.
[1] Inducible clindamycin resistance may occur in Corynebacteria. This can be detected by antagonism of clindamycin activity by a macrolide agent. The clinical significance is unknown. There is currently no recommendation for testing.
[1] Inducible clindamycin resistance may occur in Corynebacteria. This can be detected by antagonism of clindamycin activity by a macrolide agent. The clinical significance is unknown. There is currently no recommendation for testing.
[A] Non-wild typeisolates were not available when developing the disk diffusion method.
[A] Examine zones carefully for colonies within zones. Colonies should be taken into account when reading.
[1] For susceptibility testing purposes, the concentration of  tazobactam is fixed at 4 mg/L.
[A] For other Enterobacterales, the activity of tigecycline varies from insufficient in Proteus spp., Morganella morganii and Providencia spp. to variable in other species. For more information, see https://www.eucast.org/eucastguidancedocuments/. | [B] Zone diameter breakpoints validated for E. coli only. For C. koseri, use an MIC method.
[2] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [3] For other Enterobacterales, the activity of tigecycline varies from insufficient in Proteus spp., Morganella morganii and Providencia spp. to variable in other species. For more information, see https://www.eucast.org/eucastguidancedocuments/.
[A] Examine zones carefully for colonies within zones. Colonies should be taken into account when reading.
[1] For susceptibility testing purposes, the concentration of  tazobactam is fixed at 4 mg/L.
[2] Susceptibility to ampicillin, amoxicillin and piperacillin (with and without beta-lactamase inhibitor) can be inferred from ampicillin. Ampicillin resistance is uncommon in E. faecalis (confirm with MIC) but common in E. faecium. | [4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L. | [1] Aminopenicillin breakpoints in enterococci are based on intravenous administration. For oral administration the breakpoints are relevant for urinary tract infections only.
[A] Susceptibility to ampicillin, amoxicillin and piperacillin (with and without beta-lactamase inhibitor) can be inferred from ampicillin. Ampicillin resistance is uncommon in E. faecalis (confirm with MIC) but common in E. faecium. | [1] Aminopenicillin breakpoints in enterococci are based on intravenous administration. For oral administration the breakpoints are relevant for urinary tract infections only.
[2] Susceptibility to ampicillin, amoxicillin and piperacillin (with and without beta-lactamase inhibitor) can be inferred from ampicillin. Ampicillin resistance is uncommon in E. faecalis (confirm with MIC) but common in E. faecium. | [1] Aminopenicillin breakpoints in enterococci are based on intravenous administration. For oral administration the breakpoints are relevant for urinary tract infections only.
[2] Susceptibility to ampicillin, amoxicillin and piperacillin (with and without beta-lactamase inhibitor) can be inferred from ampicillin. Ampicillin resistance is uncommon in E. faecalis (confirm with MIC) but common in E. faecium. | [1] Aminopenicillin breakpoints in enterococci are based on intravenous administration. For oral administration the breakpoints are relevant for urinary tract infections only.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[C]  | [C] Susceptibility to ciprofloxacin and levofloxacin can be inferred from the norfloxacin disk diffusion screening test. For moxifloxacin, see comment 1/B.
[2] Susceptibility to ampicillin, amoxicillin and piperacillin (with and without beta-lactamase inhibitor) can be inferred from ampicillin. Ampicillin resistance is uncommon in E. faecalis (confirm with MIC) but common in E. faecium. | [3] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L. | [1] Aminopenicillin breakpoints in enterococci are based on intravenous administration. For oral administration the breakpoints are relevant for urinary tract infections only.
[A] Vancomycin susceptible enterococci exhibit sharp zone edges and do not exhibit colonies in the inhibition zone. Examine zone edges with transmitted light (plate held up to light). If the zone edge is fuzzy, colonies grow within the zone  or if you are uncertain, then perform confirmatory testing with PCR or report resistant (see pictures below) even if the zone diameter is ≥ 12 mm. Isolates must not be reported susceptible before 24 h incubation.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Isolates susceptible to cefadroxil and/or cefalexin can be reported "susceptible, increased exposure” (I) to cefazolin.
[2] Isolates susceptible to cefadroxil and/or cefalexin can be reported "susceptible, increased exposure” (I) to cefazolin.
[D] Ignore isolated colonies within the inhibition zone (see pictures below).
[4] Agar dilution is the reference method for fosfomycin. MICs must be determined in the presence of glucose-6-phosphate (25 mg/L in the medium). Follow the manufacturers' instructions for commercial systems.
[C] Ignore isolated colonies within the inhibition zone.
[A] For other Enterobacterales, the activity of tigecycline varies from insufficient in Proteus spp., Morganella morganii and Providencia spp. to variable in other species. For more information, see https://www.eucast.org/eucastguidancedocuments/. | [B] Zone diameter breakpoints validated for E. coli only. For C. koseri, use an MIC method.
[2] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [3] For other Enterobacterales, the activity of tigecycline varies from insufficient in Proteus spp., Morganella morganii and Providencia spp. to variable in other species. For more information, see https://www.eucast.org/eucastguidancedocuments/.
[A] Examine zones carefully for colonies within zones. Colonies should be taken into account when reading.
[1] For susceptibility testing purposes, the concentration of  tazobactam is fixed at 4 mg/L.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[5] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[5] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below. | [2] Beta-lactamase positive isolates can be reported resistant to ampicillin, amoxicillin and piperacillin without inhibitors. Tests based on a chromogenic cephalosporin can be used to detect the beta-lactamase.
[2] Beta-lactamase positive isolates can be reported resistant to ampicillin, amoxicillin and piperacillin without inhibitors. Tests based on a chromogenic cephalosporin can be used to detect the beta-lactamase.
[2] Beta-lactamase positive isolates can be reported resistant to ampicillin, amoxicillin and piperacillin without inhibitors. Tests based on a chromogenic cephalosporin can be used to detect the beta-lactamase.
[2] Beta-lactamase positive isolates can be reported resistant to ampicillin, amoxicillin and piperacillin without inhibitors. Tests based on a chromogenic cephalosporin can be used to detect the beta-lactamase.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[1] For chloramphenicol treatment in meningitis, see table of dosages.
[1] For chloramphenicol treatment in meningitis, see table of dosages.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below. | [D] For benzylpenicillin 1 unit disk screen positive isolates (inhibition zone <12 mm), determine the MIC.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below. | [D] For benzylpenicillin 1 unit disk screen positive isolates (inhibition zone <12 mm), determine the MIC.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below. | [2] See table of dosages for dosing for different indications.
[2] See table of dosages for dosing for different indications.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all carbapenems for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all carbapenems for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all carbapenems for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all carbapenems for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[B]  | [B] Isolates categorised as screen negative can be reported susceptible to ciprofloxacin, levofloxacin, moxifloxacin and ofloxacin. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for gram positive organisms and nalidixic acid for H. influenzae and M. catarrhalis).
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[1/A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[3] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L. | [4] Susceptibility can be inferred from amoxicillin-clavulanic acid iv.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[A] The benzylpenicillin 1 unit disk diffusion screening test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[6] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[2] Susceptibility can be inferred from benzylpenicillin susceptibility.
[2] Susceptibility can be inferred from benzylpenicillin susceptibility.
[1] Susceptibility can be inferred from erythromycin susceptibility.
[1] Susceptibility can be inferred from erythromycin susceptibility.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible can be reported susceptible to doxycycline. Isolates categorised as resistant should be tested for susceptibility to doxycycline or reported resistant.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Isolates susceptible to cefadroxil and/or cefalexin can be reported "susceptible, increased exposure” (I) to cefazolin.
[2] Isolates susceptible to cefadroxil and/or cefalexin can be reported "susceptible, increased exposure” (I) to cefazolin.
[C] Ignore isolated colonies within the inhibition zone.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[A] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[B]  | [B] Isolates categorised as screen negative can be reported susceptible to ciprofloxacin, levofloxacin, moxifloxacin and ofloxacin. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for gram positive organisms and nalidixic acid for H. influenzae and M. catarrhalis).
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L. | [3] Susceptibility can be inferred from amoxicillin-clavulanic acid.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as susceptible to tetracycline can be reported susceptible to doxycycline and minocycline. Isolates categorised as resistant to tetracycline should be tested for susceptibility to individual agents or reported resistant.
[1] Breakpoints were determined on MICs performed on Middlebrook 7H11/7H10 medium. The comparability of tests performed by other media has not been established. There is ongoing work to review breakpoints using the EUCAST reference method (described above).
[1] Always test for beta-lactamase (tests based on a chromogenic cephalosporin can be used). If beta-lactamase positive, report resistant to ampicillin and amoxicillin. If beta-lactamase negative, determine the MIC of benzylpenicillin. Infer the susceptibility to ampicillin and amoxicillin from the benzylpenicillin MIC (do not report benzylpenicillin susceptibility).
[1] For chloramphenicol treatment in meningitis, see table of dosages.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory. | [2] Breakpoints for serious N. meningitidis systemic infections (meningitis with or without septicemia) have been determined for meropenem only. 3.The addition of the beta-lactamase inhibitor does not add clinical benefit.
[1] Tetracycline can be used to predict susceptibility to minocycline for prophylaxis against N. meningitidis infections.
[1] Tetracycline can be used to predict susceptibility to minocycline for prophylaxis against N. meningitidis infections.
[C] Ignore isolated colonies within the inhibition zone.
[A] Examine zones carefully for colonies within zones. Colonies should be taken into account when reading.
[1] For susceptibility testing purposes, the concentration of  tazobactam is fixed at 4 mg/L.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[2] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [1] Colistin MIC determination should be performed with broth microdilution. Quality control must be performed with both a susceptible QC strain (E. coli ATCC 25922 or P. aeruginosa ATCC 27853) and the colistin resistant E. coli NCTC 13846 (mcr-1 positive).
[2] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[2] For susceptibility testing purposes, the concentration of avibactam is fixed at 4 mg/L.
[3] See table of dosages for dosing for different indications.
[4] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L. | [3] See table of dosages for dosing for different indications.
[1] Broth microdilution MIC determination must be performed in iron-depleted Mueller-Hinton broth and specific reading instructions must be followed. For testing conditions and reading instructions, see https://www.eucast.org/eucastguidancedocuments/.
[1] For susceptibility testing purposes, the concentration of relebactam is fixed at 4 mg/L.
[2] For susceptibility testing purposes, the concentration of vaborbactam is fixed at 8 mg/L.
[1] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note B.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note B.
[B] Isolates categorised as screen negative can be reported susceptible to ciprofloxacin and levofloxacin. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Susceptibility to doxycycline can be inferred from the tetracycline disk diffusion screening test.
[1] There is clinical evidence for ciprofloxacin to indicate a poor response in systemic infections caused by Salmonella spp. with low-level ciprofloxacin resistance (MIC >0.06 mg/L). The available data relate mainly to  Salmonella Typhi but there are also case reports of poor response with other Salmonella species.
[2/C] The pefloxacin 5 µg breakpoint used to screen for clinical fluoroquinolone resistance in Salmonella spp., can also be used to detect fluoroquinolone resistance mechanisms in other Enterobacterales such as E. coli, K. pneumoniae and Shigella spp. | [B]  | [B] Susceptibility of Salmonella spp. to ciprofloxacin can be inferred from the pefloxacin disk diffusion screening test. | [1] There is clinical evidence for ciprofloxacin to indicate a poor response in systemic infections caused by Salmonella spp. with low-level ciprofloxacin resistance (MIC >0.06 mg/L). The available data relate mainly to  Salmonella Typhi but there are also case reports of poor response with other Salmonella species.
[A] There may be growth within the inhibition zone. The density of growth may vary from a fine haze to substantial growth (see pictures below). If any zone edge can be seen, ignore growth within the inhibition zone and read the zone diameter. | [1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Erythromycin can be used to screen for macrolide resistance in staphylococci. Isolates categorised as screen negative can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] The clinical efficacy of chloramphenicol in meningitis has been questioned and breakpoints are currently under review. For chloramphenicol treatment in meningitis, see table of dosages.
[1] The clinical efficacy of chloramphenicol in meningitis has been questioned and breakpoints are currently under review. For chloramphenicol treatment in meningitis, see table of dosages.
[B] Place the erythromycin and clindamycin disks 12-20 mm apart (edge to edge) and look for antagonism (the D phenomenon) to detect inducible clindamycin resistance. | [2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant and consider adding this comment to the report: "Clindamycin may still be used for short-term therapy of less serious skin and soft tissue infections as constitutive resistance is unlikely to develop during such therapy".
[2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant and consider adding this comment to the report: "Clindamycin may still be used for short-term therapy of less serious skin and soft tissue infections as constitutive resistance is unlikely to develop during such therapy".
[1] Erythromycin can be used to screen for macrolide resistance in staphylococci. Isolates categorised as screen negative can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[3] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturer's instructions for commercial systems. | [4] S. aureus isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin.
[3] Daptomycin MICs must be determined in the presence of Ca (50 mg/L in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturers' instructions for commercial systems. | [2] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as screen negative can be reported susceptible to doxycycline and minocycline. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[A] Erythromycin can be used to screen for macrolide resistance in staphylococci. Isolates categorised as screen negative can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Erythromycin can be used to screen for macrolide resistance in staphylococci. Isolates categorised as screen negative can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[4] Agar dilution is the reference method for fosfomycin. MICs must be determined in the presence of glucose-6-phosphate (25 mg/L in the medium). Follow the manufacturers' instructions for commercial systems.
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as screen negative can be reported susceptible to doxycycline and minocycline. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as screen negative can be reported susceptible to doxycycline and minocycline. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[C]  | [C] Isolates categorised as screen negative can be reported susceptible to moxifloxacin and "susceptible increased exposure" (I) to ciprofloxacin and levofloxacin. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Erythromycin can be used to screen for macrolide resistance in staphylococci. Isolates categorised as screen negative can be reported susceptible to azithromycin, clarithromycin and roxithromycin. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[5] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[5] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as screen negative can be reported susceptible to doxycycline and minocycline. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as screen negative can be reported susceptible to doxycycline and minocycline. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[2] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[3] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [2] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Isolates susceptible to linezolid can be reported susceptible to tedizolid.
[1] Isolates susceptible to linezolid can be reported susceptible to tedizolid.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [2] Resistance to amikacin is most reliably determined by testing with kanamycin (MIC >8 mg/L). The corresponding zone diameter for the kanamycin 30 µg disk is R<18 mm for S. aureus and R<22 mm for coagulase-negative staphylococci.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [2] Resistance to amikacin is most reliably determined by testing with kanamycin (MIC >8 mg/L). The corresponding zone diameter for the kanamycin 30 µg disk is R<18 mm for S. aureus and R<22 mm for coagulase-negative staphylococci.
[F] Methicillin-susceptible isolates can be reported susceptible to ceftobiprole without further testing.
[8] Methicillin-susceptible isolates can be reported susceptible to ceftobiprole without further testing.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[D] Methicillin-susceptible isolates can be reported susceptible to ceftaroline without further testing.
[D] Methicillin-susceptible isolates can be reported susceptible to ceftaroline without further testing.
[6] Methicillin-susceptible isolates can be reported susceptible to ceftaroline without further testing.
[6] Methicillin-susceptible isolates can be reported susceptible to ceftaroline without further testing.
[B] For MRSA that test susceptible with disk diffusion, the results should be confirmed with an MIC test.
[A] Susceptibility of staphylococci to cephalosporins is inferred from the cefoxitin susceptibility except for cefixime, ceftazidime, ceftazidime-avibactam, ceftibuten and ceftolozane-tazobactam, which do not have breakpoints and should not be used for staphylococcal infections. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. If cefotaxime and ceftriaxone are reported for methicillin-susceptible staphylococci, these should be reported “Susceptible, increased exposure” (I). Some methicillin-resistant S. aureus are susceptible to ceftaroline and ceftobiprole, see Notes 5/D and 7/F. | [B] If coagulase-negative staphylococci are not identified to species level, use zone diameter breakpoints S≥25, R<25 mm.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[2] Breakpoints for nasal decontamination S ≤1, R >256 mg/L (S ≥30, R <18 mm for the mupirocin 200 µg disk). Isolates in the I category are associated with short term suppression (useful preoperatively) but, unlike fully susceptible isolates, long term eradication rates are low.
ND = No ECOFF available.
[2] Breakpoints for nasal decontamination S ≤1, R >256 mg/L (S ≥30, R <18 mm for the mupirocin 200 µg disk). Isolates in the I category are associated with short term suppression (useful preoperatively) but, unlike fully susceptible isolates, long term eradication rates are low.
ND = No ECOFF available.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for gram positive organisms and nalidixic acid for H. influenzae and M. catarrhalis).
[3] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturer's instructions for commercial systems. | [4] S. aureus isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin.
[A] Most S. aureus are penicillinase producers and some are methicillin resistant. Either mechanism renders them resistant to benzylpenicillin, phenoxymethylpenicillin, ampicillin, amoxicillin, piperacillin and ticarcillin. Isolates that test susceptible to benzylpenicillin and cefoxitin can be reported susceptible to all penicillins. Isolatesthat test resistant to benzylpenicillin but susceptible to cefoxitin are susceptible to β-lactam β-lactamase inhibitor combinations, the isoxazolylpenicillins (oxacillin, cloxacillin, dicloxacillin and flucloxacillin) and nafcillin. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. Isolates that test resistant to cefoxitin are resistant to all penicillins. | [B] For S. aureus, disk diffusion is more reliable than MIC determination for detection of penicillinase producers, provided the zone diameter is measured AND the zone edge closely inspected (see pictures below). Examine the zone edge with transmitted light (plate held up to light). If the zone diameter is <26 mm, then report resistant. If the zone diameter is ≥26 mm AND the zone edge is sharp (no reduction of growth towards zone edge, like a "cliff"), then report resistant. If not sharp (reduction of growth towards zone edge,  like a "beach"), then report susceptible and if uncertain, then report resistant. Chromogenic cephalosporin-based beta-lactamase tests do not reliably detect staphylococcal penicillinase.
[1] Most S. aureus are penicillinase producers and some are methicillin resistant. Either mechanism renders them resistant to benzylpenicillin, phenoxymethylpenicillin, ampicillin, amoxicillin, piperacillin and ticarcillin. Isolates that test susceptible to benzylpenicillin and cefoxitin can be reported susceptible to all penicillins. Isolatesthat test resistant to benzylpenicillin but susceptible to cefoxitin are susceptible to β-lactam β-lactamase inhibitor combinations, the isoxazolylpenicillins (oxacillin, cloxacillin, dicloxacillin and flucloxacillin) and nafcillin. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. Isolates that test resistant to cefoxitin are resistant to all penicillins.
[3] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturer's instructions for commercial systems. | [5] MRSA isolates susceptible to vancomycin can be reported susceptible to telavancin.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[E] For screening for methicillin resistance in S. pseudintermedius, S. schleiferi and S. coagulans.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [2] Resistance to amikacin is most reliably determined by testing with kanamycin (MIC >8 mg/L). The corresponding zone diameter for the kanamycin 30 µg disk is R<18 mm for S. aureus and R<22 mm for coagulase-negative staphylococci.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [2] Resistance to amikacin is most reliably determined by testing with kanamycin (MIC >8 mg/L). The corresponding zone diameter for the kanamycin 30 µg disk is R<18 mm for S. aureus and R<22 mm for coagulase-negative staphylococci.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Susceptibility of staphylococci to cephalosporins is inferred from the cefoxitin susceptibility except for cefixime, ceftazidime, ceftazidime-avibactam, ceftibuten and ceftolozane-tazobactam, which do not have breakpoints and should not be used for staphylococcal infections. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. If cefotaxime and ceftriaxone are reported for methicillin-susceptible staphylococci, these should be reported “Susceptible, increased exposure” (I). Some methicillin-resistant S. aureus are susceptible to ceftaroline and ceftobiprole, see Notes 5/D and 7/F. | [B] If coagulase-negative staphylococci are not identified to species level, use zone diameter breakpoints S≥25, R<25 mm.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] Susceptibility of staphylococci to cephalosporins is inferred from the cefoxitin susceptibility except for cefixime, ceftazidime, ceftazidime-avibactam, ceftibuten and ceftolozane-tazobactam, which do not have breakpoints and should not be used for staphylococcal infections. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. If cefotaxime and ceftriaxone are reported for methicillin-susceptible staphylococci, these should be reported “Susceptible, increased exposure” (I). Some methicillin-resistant S. aureus are susceptible to ceftaroline and ceftobiprole, see Notes 5/D and 7/F. | [B] If coagulase-negative staphylococci are not identified to species level, use zone diameter breakpoints S≥25, R<25 mm.
[A] Susceptibility of staphylococci to cephalosporins is inferred from the cefoxitin susceptibility except for cefixime, ceftazidime, ceftazidime-avibactam, ceftibuten and ceftolozane-tazobactam, which do not have breakpoints and should not be used for staphylococcal infections. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. If cefotaxime and ceftriaxone are reported for methicillin-susceptible staphylococci, these should be reported “Susceptible, increased exposure” (I). Some methicillin-resistant S. aureus are susceptible to ceftaroline and ceftobiprole, see Notes 5/D and 7/F. | [B] If coagulase-negative staphylococci are not identified to species level, use zone diameter breakpoints S≥25, R<25 mm.
[E] For screening for methicillin resistance in S. pseudintermedius, S. schleiferi and S. coagulans.
[E] For screening for methicillin resistance in S. pseudintermedius, S. schleiferi and S. coagulans.
[C] Most  staphylococci are penicillinase producers and some are methicillin resistant. Either mechanism renders them resistant to benzylpenicillin, phenoxymethylpenicillin, ampicillin, amoxicillin, piperacillin and ticarcillin. No currently available method can reliably detect penicillinase production in all species of staphylococci but methicillin resistance can be detected with cefoxitin as described. | [D] Ampicillin susceptible S. saprophyticus are mecA-negative and susceptible to ampicillin, amoxicillin and piperacillin (without or with a beta-lactamase inhibitor).
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[1] The clinical efficacy of chloramphenicol in meningitis has been questioned and breakpoints are currently under review. For chloramphenicol treatment in meningitis, see table of dosages.
[1] The clinical efficacy of chloramphenicol in meningitis has been questioned and breakpoints are currently under review. For chloramphenicol treatment in meningitis, see table of dosages.
[B] Place the erythromycin and clindamycin disks 12-16 mm apart (edge to edge) and look for antagonism (the D phenomenon) to detect inducible clindamycin resistance. | [2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant and consider adding this comment to the report: "Clindamycin may still be used for short-term therapy of less serious skin and soft tissue infections as constitutive resistance is unlikely to develop during such therapy". The clinical importance of inducible clindamycin resistance in combination treatment of severe S. pyogenes infections is not known.
[2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant and consider adding this comment to the report: "Clindamycin may still be used for short-term therapy of less serious skin and soft tissue infections as constitutive resistance is unlikely to develop during such therapy". The clinical importance of inducible clindamycin resistance in combination treatment of severe S. pyogenes infections is not known.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[2] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturer's instructions for commercial systems. | [3] Isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[3] Daptomycin MICs must be determined in the presence of Ca (50 mg/L in the medium for broth dilution methods; agar dilution methods have not been validated).  Follow the manufacturer's instructions for commercial systems. | [2] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as screen negative can be reported susceptible to doxycycline and minocycline. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[A] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[B] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[B] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as screen negative can be reported susceptible to doxycycline and minocycline. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as screen negative can be reported susceptible to doxycycline and minocycline. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[C]  | [C] Isolates categorised as screen negative can be reported susceptible to moxifloxacin and as "susceptible increased exposure" (I) to levofloxacin. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for gram positive organisms and nalidixic acid for H. influenzae and M. catarrhalis).
[2] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturer's instructions for commercial systems. | [3] Isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[4] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[4] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as screen negative can be reported susceptible to doxycycline and minocycline. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as screen negative can be reported susceptible to doxycycline and minocycline. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[B] Non-wild type isolates were not available when developing the disk diffusion method. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[3] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [2] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Isolates susceptible to linezolid can be reported susceptible to tedizolid. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] Isolates susceptible to linezolid can be reported susceptible to tedizolid. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[B] Non-wild type isolates were not available when developing the disk diffusion method. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturer's instructions for commercial systems. | [3] Isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturer's instructions for commercial systems. | [3] Isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[5] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L. | [3] The addition of a beta-lactamase inhibitor does not add clinical benefit.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[1] The clinical efficacy of chloramphenicol in meningitis has been questioned and breakpoints are currently under review.For chloramphenicol treatment in meningitis, see table of dosages.
[1] The clinical efficacy of chloramphenicol in meningitis has been questioned and breakpoints are currently under review.For chloramphenicol treatment in meningitis, see table of dosages.
[B] Place the erythromycin and clindamycin disks 12-16 mm apart (edge to edge) and look for antagonism (the D phenomenon) to detect inducible clindamycin resistance. | [2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant.
[2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as screen negative can be reported susceptible to doxycycline and minocycline. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[A] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as screen negative can be reported susceptible to doxycycline and minocycline. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as screen negative can be reported susceptible to doxycycline and minocycline. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[B]  | [B] Isolates categorised as screen negative can be reported susceptible to moxifloxacin and as "susceptible increased exposure" (I) to levofloxacin. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for gram positive organisms and nalidixic acid for H. influenzae and M. catarrhalis).
[D] For interpretation of the oxacillin disk screen, see flow chart below. | [1] The oxacillin 1 µg disk diffusion screening test or a benzylpenicillin MIC test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (oxacillin inhibition zone ≥20 mm, or benzylpenicillin MIC ≤0.06 mg/L) all beta-lactam agents for which clinical breakpoints are available, including those with “Note” can be reported susceptible without further testing, except for cefaclor, which if reported, should be reported as “susceptible, increased exposure” (I). When the screen is positive (oxacillin zone <20 mm, or benzylpenicillin MIC >0.06 mg/L), see flow chart below.
[2] For breakpoints and dosing in pneumonia, see table of dosages.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as screen negative can be reported susceptible to doxycycline and minocycline. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Tetracycline can be used to screen for resistance in tetracycline agents. Isolates categorised as screen negative can be reported susceptible to doxycycline and minocycline. Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[A] Non-wild typeisolates were not available when developing the disk diffusion method. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Non-wild typeisolates were not available when developing the disk diffusion method. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Place the erythromycin and clindamycin disks 12-16 mm apart (edge to edge) and look for antagonism (the D phenomenon) to detect inducible clindamycin resistance. | [1] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant.
[1] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant.
[A] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. See Note 1/A on penicillins.
[A] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. See Note 1/A on penicillins.
[A] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. See Note 1/A on penicillins.
[A] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. See Note 1/A on penicillins.
[1] For susceptibility testing purposes, the concentration of relebactam is fixed at 4 mg/L. | [2] The addition of a beta-lactamase inhibitor does not add clinical benefit.
[A] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. Isolates categorised as screen negative can be reported susceptible to beta-lactam agents for which clinical breakpoints are listed (including those with “Note”). Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[1] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. Isolates categorised as screen negative can be reported susceptible to beta-lactam agents for which clinical breakpoints are listed (including those with “Note”). Isolates categorised as screen positive should be tested for susceptibility to individual agents or reported resistant.
[B] Non-wild type isolates were not available when developing the disk diffusion method. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[B] Non-wild type isolates were not available when developing the disk diffusion method. | [1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Resistant isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Susceptibility to azithromycin can be inferred from the erythromycin disk diffusion screening test.
[A] Susceptibility to ciprofloxacin and levofloxacin can be inferred from the pefloxacin disk diffusion screening test.
[A] Susceptibility to azithromycin can be inferred from the erythromycin disk diffusion screening test.
[A] Susceptibility to ciprofloxacin and levofloxacin can be inferred from the pefloxacin disk diffusion screening test.
[A] Susceptibility to ciprofloxacin and levofloxacin can be inferred from the pefloxacin disk diffusion screening test.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Susceptibility to doxycycline can be inferred from the tetracycline disk diffusion screening test.
[1] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[2] The intrinsically low activity of imipenem against Morganella morganii, Proteus spp. and Providencia spp. requires the high exposure of imipenem.
[2] The intrinsically low activity of imipenem against Morganella morganii, Proteus spp. and Providencia spp. requires the high exposure of imipenem.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] Aminopenicillin breakpoints in Enterobacterales are based on intravenous administration. For oral administration the breakpoints are relevant for urinary tract infections only. Breakpoints for other infections are under review.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars.
[3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L. | [1] Aminopenicillin breakpoints in Enterobacterales are based on intravenous administration. For oral administration the breakpoints are relevant for urinary tract infections only. Breakpoints for other infections are under review.
[3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] Aminopenicillin breakpoints in Enterobacterales are based on intravenous administration. For oral administration the breakpoints are relevant for urinary tract infections only. Breakpoints for other infections are under review.
[1] Aminopenicillin breakpoints in Enterobacterales are based on intravenous administration. For oral administration the breakpoints are relevant for urinary tract infections only. Breakpoints for other infections are under review.
[1] Aminopenicillin breakpoints in Enterobacterales are based on intravenous administration. For oral administration the breakpoints are relevant for urinary tract infections only. Breakpoints for other infections are under review.
[1] The aztreonam breakpoints for Enterobacterales will detect clinically important resistance mechanisms (including ESBL). Some isolates that produce beta-lactamases are susceptible to aztreonam with these breakpoints and should be reported as tested, i.e. the presence or absence of an ESBL does not in itself influence the categorisation of susceptibility. ESBL detection and characterisation are recommended for public health and infection control purposes.
[1] The aztreonam breakpoints for Enterobacterales will detect clinically important resistance mechanisms (including ESBL). Some isolates that produce beta-lactamases are susceptible to aztreonam with these breakpoints and should be reported as tested, i.e. the presence or absence of an ESBL does not in itself influence the categorisation of susceptibility. ESBL detection and characterisation are recommended for public health and infection control purposes.
[1] The clinical efficacy of chloramphenicol in meningitis has been questioned and breakpoints are currently under review. For chloramphenicol treatment in meningitis, see table of dosages.
[1] The clinical efficacy of chloramphenicol in meningitis has been questioned and breakpoints are currently under review. For chloramphenicol treatment in meningitis, see table of dosages.
[3] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/. | [2] Colistin MIC determination should be performed with broth microdilution. Quality control must be performed with both a susceptible QC strain (E. coli ATCC 25922 or P. aeruginosa ATCC 27853) and the colistin resistant E. coli NCTC 13846 (mcr-1 positive).
[5] For susceptibility testing purposes, the concentration of avibactam is fixed at 4 mg/L.
[6] See table of dosages for dosing for different indications.
[7] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L. | [6] See table of dosages for dosing for different indications.
[3] Broth microdilution MIC determination must be performed in iron-depleted Mueller-Hinton broth and specific reading instructions must be followed. For testing conditions and reading instructions, see https://www.eucast.org/eucastguidancedocuments/.
[C] Zone diameter breakpoints apply to E. coli only. For other Enterobacterales, use an MIC method. | [D] Ignore isolated colonies within the inhibition zone (see pictures below).
[4] Agar dilution is the reference method for fosfomycin. MICs must be determined in the presence of glucose-6-phosphate (25 mg/L in the medium). Follow the manufacturers' instructions for commercial systems.
[4] The cefoxitin ECOFF (8 mg/L) has a high sensitivity but poor specificity for identification of AmpC-producing Enterobacterales as this agent is also affected by permeability alterations and some carbapenemases. Classical non-AmpC producers are wild type, whereas plasmid AmpC producers or chromosomal AmpC hyperproducers are non-wild type.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[3] For susceptibility testing purposes, the concentration of relebactam is fixed at 4 mg/L.
[4] For susceptibility testing purposes, the concentration of vaborbactam is fixed at 8 mg/L.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for gram positive organisms and nalidixic acid for H. influenzae and M. catarrhalis).
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] Aminopenicillin breakpoints in Enterobacterales are based on intravenous administration. For oral administration the breakpoints are relevant for urinary tract infections only. Breakpoints for other infections are under review.
[2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L. | [1] Aminopenicillin breakpoints in Enterobacterales are based on intravenous administration. For oral administration the breakpoints are relevant for urinary tract infections only. Breakpoints for other infections are under review.
[5] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[5] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[1] For information on how to use breakpoints in brackets, see https://www.eucast.org/eucastguidancedocuments/.
[4] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[C] Ignore isolated colonies within the inhibition zone.
[5] Agar dilution is the reference method for mecillinam MIC determination.
[A] There may be growth within the inhibition zone. The density of growth may vary from a fine haze to substantial growth (see pictures below). If any zone edge can be seen, ignore growth within the inhibition zone and read the zone diameter. | [1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[A] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[1] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[1] Colistin MIC determination should be performed with broth microdilution. Quality control must be performed with both a susceptible QC strain (E. coli ATCC 25922 or P. aeruginosa ATCC 27853) and the colistin resistant E. coli NCTC 13846 (mcr-1 positive).
[A] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[1] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[2] The beta-lactamases produced by the organisms either do not modify the parent carbapenem or are not affected by the inhibitor. Therefore the addition of the beta-lactamase inhibitor does not add clinical benefit.
[1] For susceptibility testing purposes, the concentration of relebactam is fixed at 4 mg/L. | [2] The beta-lactamases produced by the organisms either do not modify the parent carbapenem or are not affected by the inhibitor. Therefore the addition of the beta-lactamase inhibitor does not add clinical benefit.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[1] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[A] Susceptibility can be inferred from norfloxacin susceptibility. See Note
[1] Susceptibility can be inferred from ciprofloxacin susceptibility.
[C]  | [C] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance.
[A] Non-wild type isolates were not available when developing the disk diffusion method.
[A] Susceptibility can be inferred from norfloxacin susceptibility. See Note
[1] Susceptibility can be inferred from ciprofloxacin susceptibility.
[C]  | [C] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance.
[A] Non-wild type isolates were not available when developing the disk diffusion method.
[A] Read the obvious zone edge and disregard haze or growth within the inhibition zone (see pictures below). | [1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[B]  | [B] Isolates categorised as susceptible to norfloxacin can be reported "susceptible increased exposure" (I) to ciprofloxacin and levofloxacin. Isolates categorised as resistant to norfloxacin can be reported resistant to ciprofloxacin and levofloxacin.
[A] Non-wild type isolates were not available when developing the disk diffusion method.
[1] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] There may be growth within the inhibition zone. The density of growth may vary from a fine haze to substantial growth (see pictures below). If any zone edge can be seen, ignore growth within the inhibition zone and read the zone diameter. | [1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Susceptibility inferred from tetracycline disk diffusion screen test.
[A] Erythromycin can be used to determine susceptibility to azithromycin and clarithromycin.
[1] Erythromycin can be used to determine susceptibility to azithromycin and clarithromycin.
[A] Tetracycline can be used to determine susceptibility to doxycycline.
[1] Tetracycline can be used to determine susceptibility to doxycycline.
[A] Erythromycin can be used to determine susceptibility to azithromycin and clarithromycin.
[1] Erythromycin can be used to determine susceptibility to azithromycin and clarithromycin.
[A] Tetracycline can be used to determine susceptibility to doxycycline.
[1] Tetracycline can be used to determine susceptibility to doxycycline.
[5] The breakpoints are based on epidemiological cut-off values (ECOFFs) and apply to oral treatment of C. difficile infections with metronidazole. There are no conclusive clinical data regarding the relation between MICs and outcomes.
[1] The breakpoints are based on epidemiological cut-off values (ECOFFs) and apply to oral treatment of C. difficile infections with vancomycin. There are no conclusive clinical data regarding the relation between MICs and outcomes.
[1] Inducible clindamycin resistance may occur in Corynebacteria. This can be detected by antagonism of clindamycin activity by a macrolide agent. The clinical significance is unknown. There is currently no recommendation for testing.
[1] Inducible clindamycin resistance may occur in Corynebacteria. This can be detected by antagonism of clindamycin activity by a macrolide agent. The clinical significance is unknown. There is currently no recommendation for testing.
[A] Non-wild typeisolates were not available when developing the disk diffusion method.
[C] Ignore isolated colonies within the inhibition zone.
[5] Agar dilution is the reference method for mecillinam MIC determination.
[A] For other Enterobacterales, the activity of tigecycline varies from insufficient in Proteus spp., Morganella morganii and Providencia spp. to variable in other species. For more information, see http://www.eucast.org/guidance_documents/. | [B] Zone diameter breakpoints validated for E. coli only. For C. koseri, use an MIC method.
[2] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [3] For other Enterobacterales, the activity of tigecycline varies from insufficient in Proteus spp., Morganella morganii and Providencia spp. to variable in other species. For more information, see http://www.eucast.org/guidance_documents/.
[C] Ignore isolated colonies within the inhibition zone.
[5] Agar dilution is the reference method for mecillinam MIC determination.
[2] Susceptibility to ampicillin, amoxicillin and piperacillin (with and without beta-lactamase inhibitor) can be inferred from ampicillin. Ampicillin resistance is uncommon in E. faecalis (confirm with MIC) but common in E. faecium. | [4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L. | [1] Aminopenicillin breakpoints in enterococci are based on intravenous administration. For oral administration the breakpoints are relevant for urinary tract infections only.
[A] Susceptibility to ampicillin, amoxicillin and piperacillin (with and without beta-lactamase inhibitor) can be inferred from ampicillin. Ampicillin resistance is uncommon in E. faecalis (confirm with MIC) but common in E. faecium. | [1] Aminopenicillin breakpoints in enterococci are based on intravenous administration. For oral administration the breakpoints are relevant for urinary tract infections only.
[2] Susceptibility to ampicillin, amoxicillin and piperacillin (with and without beta-lactamase inhibitor) can be inferred from ampicillin. Ampicillin resistance is uncommon in E. faecalis (confirm with MIC) but common in E. faecium. | [1] Aminopenicillin breakpoints in enterococci are based on intravenous administration. For oral administration the breakpoints are relevant for urinary tract infections only.
[2] Susceptibility to ampicillin, amoxicillin and piperacillin (with and without beta-lactamase inhibitor) can be inferred from ampicillin. Ampicillin resistance is uncommon in E. faecalis (confirm with MIC) but common in E. faecium. | [1] Aminopenicillin breakpoints in enterococci are based on intravenous administration. For oral administration the breakpoints are relevant for urinary tract infections only.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[C]  | [C] Susceptibility of ciprofloxacin and levofloxacin can be inferred from the norfloxacin susceptibility. For moxifloxacin, see comment 1/B.
[2] Susceptibility to ampicillin, amoxicillin and piperacillin (with and without beta-lactamase inhibitor) can be inferred from ampicillin. Ampicillin resistance is uncommon in E. faecalis (confirm with MIC) but common in E. faecium. | [3] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L. | [1] Aminopenicillin breakpoints in enterococci are based on intravenous administration. For oral administration the breakpoints are relevant for urinary tract infections only.
[A] Vancomycin susceptible enterococci exhibit sharp zone edges and do not exhibit colonies in the inhibition zone. Examine zone edges with transmitted light (plate held up to light). If the zone edge is fuzzy, colonies grow within the zone  or if you are uncertain, then perform confirmatory testing with PCR or report resistant (see pictures below) even if the zone diameter is ≥ 12 mm. Isolates must not be reported susceptible before 24 h incubation.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Isolates susceptible to cefadroxil and/or cefalexin can be reported "susceptible, increased exposure” (I) to cefazolin.
[2] Isolates susceptible to cefadroxil and/or cefalexin can be reported "susceptible, increased exposure” (I) to cefazolin.
[D] Ignore isolated colonies within the inhibition zone (see pictures below).
[2] Agar dilution is the reference method for fosfomycin. MICs must be determined in the presence of glucose-6-phosphate (25 mg/L in the medium). Follow the manufacturers' instructions for commercial systems.
[C] Ignore isolated colonies within the inhibition zone.
[5] Agar dilution is the reference method for mecillinam MIC determination.
[C] Ignore isolated colonies within the inhibition zone.
[A] For other Enterobacterales, the activity of tigecycline varies from insufficient in Proteus spp., Morganella morganii and Providencia spp. to variable in other species. For more information, see http://www.eucast.org/guidance_documents/. | [B] Zone diameter breakpoints validated for E. coli only. For C. koseri, use an MIC method.
[2] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [3] For other Enterobacterales, the activity of tigecycline varies from insufficient in Proteus spp., Morganella morganii and Providencia spp. to variable in other species. For more information, see http://www.eucast.org/guidance_documents/.
[3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[1] Susceptibility to ampicillin, amoxicillin, piperacillin and ticarcillin can be inferred from susceptibility to benzylpenicillin.
[1] Susceptibility to ampicillin, amoxicillin, piperacillin and ticarcillin can be inferred from susceptibility to benzylpenicillin.
[1] For susceptibility testing purposes, the concentration of relebactam is fixed at 4 mg/L. | [2] The beta-lactamases produced by the organisms either do not modify the parent carbapenem or are not affected by the inhibitor. Therefore the addition of the beta-lactamase inhibitor does not add clinical benefit.
[1] Susceptibility to ampicillin, amoxicillin, piperacillin and ticarcillin can be inferred from susceptibility to benzylpenicillin.
[1] Susceptibility to ampicillin, amoxicillin, piperacillin and ticarcillin can be inferred from susceptibility to benzylpenicillin.
[2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L.
[3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[1] Susceptibility to ampicillin, amoxicillin, piperacillin and ticarcillin can be inferred from susceptibility to benzylpenicillin.
[4] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[2] Susceptibility to ampicillin, amoxicillin, piperacillin and ticarcillin can be inferred from susceptibility to benzylpenicillin.
[2] Susceptibility to ampicillin, amoxicillin, piperacillin and ticarcillin can be inferred from susceptibility to benzylpenicillin.
[1] For susceptibility testing purposes, the concentration of relebactam is fixed at 4 mg/L. | [2] The addition of a beta-lactamase inhibitor does not add clinical benefit.
[2] Susceptibility to ampicillin, amoxicillin, piperacillin and ticarcillin can be inferred from susceptibility to benzylpenicillin.
[2] Susceptibility to ampicillin, amoxicillin, piperacillin and ticarcillin can be inferred from susceptibility to benzylpenicillin.
[3] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L.
[4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[2] Susceptibility to ampicillin, amoxicillin, piperacillin and ticarcillin can be inferred from susceptibility to benzylpenicillin.
[5] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[5] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[5] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below. | [2] Beta-lactamase positive isolates can be reported resistant to ampicillin, amoxicillin and piperacillin without inhibitors. Tests based on a chromogenic cephalosporin can be used to detect the beta-lactamase.
[2] Beta-lactamase positive isolates can be reported resistant to ampicillin, amoxicillin and piperacillin without inhibitors. Tests based on a chromogenic cephalosporin can be used to detect the beta-lactamase.
[2] Beta-lactamase positive isolates can be reported resistant to ampicillin, amoxicillin and piperacillin without inhibitors. Tests based on a chromogenic cephalosporin can be used to detect the beta-lactamase.
[2] Beta-lactamase positive isolates can be reported resistant to ampicillin, amoxicillin and piperacillin without inhibitors. Tests based on a chromogenic cephalosporin can be used to detect the beta-lactamase.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[1] For chloramphenicol treatment in meningitis, see table of dosages.
[1] For chloramphenicol treatment in meningitis, see table of dosages.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below. | [4] The breakpoints also apply to meningitis.
[4] The breakpoints also apply to meningitis.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below. | [4] The breakpoints also apply to meningitis.
[4] The breakpoints also apply to meningitis.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below. | [2] See table of dosages for dosing for different indications.
[2] See table of dosages for dosing for different indications.
[1/A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all carbapenems for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[1] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all carbapenems for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (inhibition zone <12 mm), see flow chart below.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all carbapenems for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all carbapenems for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all carbapenems for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[B]  | [B] Isolates categorised as susceptible to nalidixic acid can be reported susceptible to ciprofloxacin, levofloxacin, moxifloxacin and ofloxacin. Isolates categorised as non-susceptible may have fluoroquinolone resistance and should be tested against the appropriate agent.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for gram positive organisms and nalidixic acid for H.influenzae and M. catarrhalis).
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[1/A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[3] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L. | [4] Susceptibility can be inferred from amoxicillin-clavulanic acid iv.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[6] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[2] Susceptibility can be inferred from benzylpenicillin susceptibility.
[2] Susceptibility can be inferred from benzylpenicillin susceptibility.
[1] Susceptibility can be inferred from erythromycin susceptibility.
[1] Susceptibility can be inferred from erythromycin susceptibility.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline, but some resistant to tetracycline may be susceptible to doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Isolates susceptible to cefadroxil and/or cefalexin can be reported "susceptible, increased exposure” (I) to cefazolin.
[2] Isolates susceptible to cefadroxil and/or cefalexin can be reported "susceptible, increased exposure” (I) to cefazolin.
[C] Ignore isolated colonies within the inhibition zone.
[5] Agar dilution is the reference method for mecillinam MIC determination.
[C] Ignore isolated colonies within the inhibition zone.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[A] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[B]  | [B] Isolates categorised as susceptible to nalidixic acid can be reported susceptible to ciprofloxacin, levofloxacin, moxifloxacin and ofloxacin. Isolates categorised as non-susceptible may have fluoroquinolone resistance and should be tested against the appropriate agent.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for gram positive organisms and nalidixic acid for H.influenzae and M. catarrhalis).
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L. | [3] Susceptibility can be inferred from amoxicillin-clavulanic acid.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[1] Breakpoints were determined on MICs performed on Middlebrook 7H11/7H10 medium. The comparability of tests performed by other media has not been established. There is ongoing work to review breakpoints using the EUCAST reference method (described above).
[1] Always test for beta-lactamase (tests based on a chromogenic cephalosporin can be used). If beta-lactamase positive, report resistant to ampicillin and amoxicillin. If beta-lactamase negative, determine the MIC of benzylpenicillin. Infer the susceptibility to ampicillin and amoxicillin from the benzylpenicillin MIC (do not report benzylpenicillin susceptibility).
[1] For chloramphenicol treatment in meningitis, see table of dosages.
[1] Breakpoints apply only to use in the prophylaxis of meningococcal disease.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory. | [2] Breakpoints for serious N. meningitidis systemic infections (meningitis with or without septicemia) have been determined for meropenem only. The meningitis breakpoint can be used to categorise meropenem for other serious infections.
[1] Tetracycline can be used to predict susceptibility to minocycline for prophylaxis against N. meningitidis infections.
[2] For prophylaxis of meningitis only (refer to national guidelines).
[1] Tetracycline can be used to predict susceptibility to minocycline for prophylaxis against N. meningitidis infections.
[C] Ignore isolated colonies within the inhibition zone.
[5] Agar dilution is the reference method for mecillinam MIC determination.
[C] Ignore isolated colonies within the inhibition zone.
[A] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[1] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[1] Colistin MIC determination should be performed with broth microdilution. Quality control must be performed with both a susceptible QC strain (E. coli ATCC 25922 or P. aeruginosa ATCC 27853) and the colistin resistant E. coli NCTC 13846 (mcr-1 positive).
[2] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[1] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[1] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[2] For susceptibility testing purposes, the concentration of avibactam is fixed at 4 mg/L.
[3] See table of dosages for dosing for different indications.
[4] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L. | [3] See table of dosages for dosing for different indications.
[1] Broth microdilution MIC determination must be performed in iron-depleted Mueller-Hinton broth and specific reading instructions must be followed. For testing conditions and reading instructions, see http://www.eucast.org/guidance_documents/.
[1] For susceptibility testing purposes, the concentration of relebactam is fixed at 4 mg/L.
[2] For susceptibility testing purposes, the concentration of vaborbactam is fixed at 8 mg/L.
[1] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note B.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note B.
[B] Isolates categorised as susceptible to nalidixic acid can be reported susceptible to ciprofloxacin and levofloxacin. Isolates categorised as non-susceptible may have fluoroquinolone resistance and should be tested against the appropriate agent.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Susceptibility inferred from tetracycline screen test.
[1] There is clinical evidence for ciprofloxacin to indicate a poor response in systemic infections caused by Salmonella spp. with low-level ciprofloxacin resistance (MIC >0.06 mg/L). The available data relate mainly to  Salmonella Typhi but there are also case reports of poor response with other Salmonella species.
[2/C] The pefloxacin 5 µg breakpoint used to screen for clinical fluoroquinolone resistance in Salmonella spp., can also be used to detect fluoroquinolone resistance mechanisms in other Enterobacterales such as E. coli, K. pneumoniae and Shigella spp. | [B]  | [B] Susceptibility of Salmonella spp. to ciprofloxacin can be inferred from pefloxacin disk diffusion susceptibility. | [1] There is clinical evidence for ciprofloxacin to indicate a poor response in systemic infections caused by Salmonella spp. with low-level ciprofloxacin resistance (MIC >0.06 mg/L). The available data relate mainly to  Salmonella Typhi but there are also case reports of poor response with other Salmonella species.
[A] There may be growth within the inhibition zone. The density of growth may vary from a fine haze to substantial growth (see pictures below). If any zone edge can be seen, ignore growth within the inhibition zone and read the zone diameter. | [1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[B] Place the erythromycin and clindamycin disks 12-20 mm apart (edge to edge) and look for antagonism (the D phenomenon) to detect inducible clindamycin resistance. | [2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant and consider adding this comment to the report: "Clindamycin may still be used for short-term therapy of less serious skin and soft tissue infections as constitutive resistance is unlikely to develop during such therapy".
[2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant and consider adding this comment to the report: "Clindamycin may still be used for short-term therapy of less serious skin and soft tissue infections as constitutive resistance is unlikely to develop during such therapy".
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[3] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturer's instructions for commercial systems. | [4] S. aureus isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin. | [2] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] Daptomycin MICs must be determined in the presence of Ca (50 mg/L in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturers' instructions for commercial systems. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[A] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[3] Agar dilution is the reference method for fosfomycin. MICs must be determined in the presence of glucose-6-phosphate (25 mg/L in the medium). Follow the manufacturers' instructions for commercial systems.
[A] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[C]  | [C] Isolates categorised as susceptible to norfloxacin can be reported susceptible to moxifloxacin and "susceptible increased exposure" (I) to ciprofloxacin, levofloxacin and ofloxacin. Isolates categorised as non-susceptible should be tested for susceptibility to individual agents.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[4] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[4] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[2] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[3] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [2] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Isolates susceptible to linezolid can be reported susceptible to tedizolid.
[1] Isolates susceptible to linezolid can be reported susceptible to tedizolid.
[A] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/. | [2] Resistance to amikacin is most reliably determined by testing with kanamycin (MIC >8 mg/L). The corresponding zone diameter for the kanamycin 30 µg disk is R<18 mm for S. aureus and R<22 mm for coagulase-negative staphylococci.
[1] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/. | [2] Resistance to amikacin is most reliably determined by testing with kanamycin (MIC >8 mg/L). The corresponding zone diameter for the kanamycin 30 µg disk is R<18 mm for S. aureus and R<22 mm for coagulase-negative staphylococci.
[F] Methicillin-susceptible isolates can be reported susceptible to ceftobiprole without further testing.
[8] Methicillin-susceptible isolates can be reported susceptible to ceftobiprole without further testing.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[D] Methicillin-susceptible isolates can be reported susceptible to ceftaroline without further testing.
[D] Methicillin-susceptible isolates can be reported susceptible to ceftaroline without further testing.
[6] Methicillin-susceptible isolates can be reported susceptible to ceftaroline without further testing.
[6] Methicillin-susceptible isolates can be reported susceptible to ceftaroline without further testing.
[B] For MRSA that test susceptible with disk diffusion, the results should be confirmed with an MIC test.
[A] Susceptibility of staphylococci to cephalosporins is inferred from the cefoxitin susceptibility except for cefixime, ceftazidime, ceftazidime-avibactam, ceftibuten and ceftolozane-tazobactam, which do not have breakpoints and should not be used for staphylococcal infections. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. If cefotaxime and ceftriaxone are reported for methicillin-susceptible staphylococci, these should be reported “Susceptible, increased exposure” (I). Some methicillin-resistant S. aureus are susceptible to ceftaroline and ceftobiprole, see Notes 5/D and 7/F. | [B] If coagulase-negative staphylococci are not identified to species level, use zone diameter breakpoints S≥25, R<25 mm.
[A] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[1] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[2] Breakpoints for nasal decontamination S ≤1, R >256 mg/L (S ≥30, R <18 mm for the mupirocin 200 µg disk). Isolates in the I category are associated with short term suppression (useful preoperatively) but, unlike fully susceptible isolates, long term eradication rates are low.
ND = No ECOFF available.
[2] Breakpoints for nasal decontamination S ≤1, R >256 mg/L (S ≥30, R <18 mm for the mupirocin 200 µg disk). Isolates in the I category are associated with short term suppression (useful preoperatively) but, unlike fully susceptible isolates, long term eradication rates are low.
ND = No ECOFF available.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for gram positive organisms and nalidixic acid for H.influenzae and M. catarrhalis).
[3] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturer's instructions for commercial systems. | [4] S. aureus isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin. | [2] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Most S. aureusare penicillinase producers and some are methicillin resistant. Either mechanism renders them resistant to benzylpenicillin, phenoxymethylpenicillin, ampicillin, amoxicillin, piperacillin and ticarcillin. Isolates that test susceptible to benzylpenicillin and cefoxitin can be reported susceptible to all penicillins. Isolatesthat test resistant to benzylpenicillin but susceptible to cefoxitin are susceptible to β-lactam β-lactamase inhibitor combinations, the isoxazolylpenicillins (oxacillin, cloxacillin, dicloxacillin and flucloxacillin) and nafcillin. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. Isolates that test resistant to cefoxitin are resistant to all penicillins. | [B] For S. aureus, disk diffusion is more reliable than MIC determination for detection of penicillinase producers, provided the zone diameter is measured AND the zone edge closely inspected (see pictures below). Examine the zone edge with transmitted light (plate held up to light). If the zone diameter is <26 mm, then report resistant. If the zone diameter is ≥26 mm AND the zone edge is sharp, then report resistant. If not sharp, then report susceptible and if uncertain, then report resistant. Chromogenic cephalosporin-based beta-lactamase tests do not reliably detect staphylococcal penicillinase.
[1] Most S. aureusare penicillinase producers and some are methicillin resistant. Either mechanism renders them resistant to benzylpenicillin, phenoxymethylpenicillin, ampicillin, amoxicillin, piperacillin and ticarcillin. Isolates that test susceptible to benzylpenicillin and cefoxitin can be reported susceptible to all penicillins. Isolatesthat test resistant to benzylpenicillin but susceptible to cefoxitin are susceptible to β-lactam β-lactamase inhibitor combinations, the isoxazolylpenicillins (oxacillin, cloxacillin, dicloxacillin and flucloxacillin) and nafcillin. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. Isolates that test resistant to cefoxitin are resistant to all penicillins.
[2] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[3] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturer's instructions for commercial systems. | [5] MRSA isolates susceptible to vancomycin can be reported susceptible to telavancin. | [2] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[1] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[2] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/. | [2] Resistance to amikacin is most reliably determined by testing with kanamycin (MIC >8 mg/L). The corresponding zone diameter for the kanamycin 30 µg disk is R<18 mm for S. aureus and R<22 mm for coagulase-negative staphylococci.
[1] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/. | [2] Resistance to amikacin is most reliably determined by testing with kanamycin (MIC >8 mg/L). The corresponding zone diameter for the kanamycin 30 µg disk is R<18 mm for S. aureus and R<22 mm for coagulase-negative staphylococci.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Susceptibility of staphylococci to cephalosporins is inferred from the cefoxitin susceptibility except for cefixime, ceftazidime, ceftazidime-avibactam, ceftibuten and ceftolozane-tazobactam, which do not have breakpoints and should not be used for staphylococcal infections. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. If cefotaxime and ceftriaxone are reported for methicillin-susceptible staphylococci, these should be reported “Susceptible, increased exposure” (I). Some methicillin-resistant S. aureus are susceptible to ceftaroline and ceftobiprole, see Notes 5/D and 7/F. | [B] If coagulase-negative staphylococci are not identified to species level, use zone diameter breakpoints S≥25, R<25 mm.
[A] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[1] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[1] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[2] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Susceptibility of staphylococci to cephalosporins is inferred from the cefoxitin susceptibility except for cefixime, ceftazidime, ceftazidime-avibactam, ceftibuten and ceftolozane-tazobactam, which do not have breakpoints and should not be used for staphylococcal infections. For agents given orally, care to achieve sufficient exposure at the site of the infection should be exercised. If cefotaxime and ceftriaxone are reported for methicillin-susceptible staphylococci, these should be reported “Susceptible, increased exposure” (I). Some methicillin-resistant S. aureus are susceptible to ceftaroline and ceftobiprole, see Notes 5/D and 7/F. | [B] If coagulase-negative staphylococci are not identified to species level, use zone diameter breakpoints S≥25, R<25 mm.
[E] For screening for methicillin resistance in S. pseudintermedius and S. schleiferi.
[E] For screening for methicillin resistance in S. pseudintermedius and S. schleiferi.
[C] Most coagulase-negative staphylococci are penicillinase producers and some are methicillin resistant. Either mechanism renders them resistant to benzylpenicillin, phenoxymethylpenicillin, ampicillin, amoxicillin, piperacillin and ticarcillin. No currently available method can reliably detect penicillinase production in coagulase-negative staphylococci but methicillin resistance can be detected with cefoxitin as described. | [D] Ampicillin susceptible S. saprophyticus are mecA-negative and susceptible to ampicillin, amoxicillin and piperacillin (without or with a beta-lactamase inhibitor).
4.S. aureus,S. lugdunensis and S. saprophyticus with oxacillin MIC values >2 mg/L are mostly methicillin resistant due to the presence of the mecA or mecC gene. Occasionally oxacillin MIC values are high in S. aureus in absence of mec-gene mediated resistance. These isolates have been called BORSA (borderline oxacillin resistant S. aureus). EUCAST does not recommend systematic screening for BORSA. For coagulase-negative staphylococci other than S. saprophyticus and S. lugdunensis, the oxacillin MIC in methicillin resistant isolates is >0.25 mg/L.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[B] Place the erythromycin and clindamycin disks 12-16 mm apart (edge to edge) and look for antagonism (the D phenomenon) to detect inducible clindamycin resistance. | [2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant and consider adding this comment to the report: "Clindamycin may still be used for short-term therapy of less serious skin and soft tissue infections as constitutive resistance is unlikely to develop during such therapy". The clinical importance of inducible clindamycin resistance in combination treatment of severe S. pyogenes infections is not known.
[2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant and consider adding this comment to the report: "Clindamycin may still be used for short-term therapy of less serious skin and soft tissue infections as constitutive resistance is unlikely to develop during such therapy". The clinical importance of inducible clindamycin resistance in combination treatment of severe S. pyogenes infections is not known.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[2] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturer's instructions for commercial systems. | [3] Isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] Daptomycin MICs must be determined in the presence of Ca (50 mg/L in the medium for broth dilution methods; agar dilution methods have not been validated).  Follow the manufacturer's instructions for commercial systems. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[A] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[B] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[B] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[C]  | [C] Isolates categorised as susceptible to norfloxacin can be reported susceptible to moxifloxacin and as "susceptible increased exposure" (I) to levofloxacin. Isolates categorised as non-susceptible should be tested for susceptibility to individual agents.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for gram positive organisms and nalidixic acid for H.influenzae and M. catarrhalis).
[2] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturer's instructions for commercial systems. | [3] Isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[3] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[3] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[B] Non-wild type isolates were not available when developing the disk diffusion method. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[3] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [2] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Isolates susceptible to linezolid can be reported susceptible to tedizolid. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] Isolates susceptible to linezolid can be reported susceptible to tedizolid. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[B] Non-wild type isolates were not available when developing the disk diffusion method. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturer's instructions for commercial systems. | [3] Isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturer's instructions for commercial systems. | [3] Isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] The oxacillin 1 µg disk screen test or a benzylpenicillin MIC test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (oxacillin inhibition zone ≥20 mm, or benzylpenicillin MIC ≤0.06 mg/L) all beta-lactam agents for which clinical breakpoints are available, including those with “Note” can be reported susceptible without further testing, except for cefaclor, which if reported, should be reported as “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <20 mm, or benzylpenicillin MIC >0.06 mg/L), see flow chart below. | [5] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L. | [3] The addition of a beta-lactamase inhibitor does not add clinical benefit.
[A] The oxacillin 1 µg disk screen test or a benzylpenicillin MIC test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (oxacillin inhibition zone ≥20 mm, or benzylpenicillin MIC ≤0.06 mg/L) all beta-lactam agents for which clinical breakpoints are available, including those with “Note” can be reported susceptible without further testing, except for cefaclor, which if reported, should be reported as “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <20 mm, or benzylpenicillin MIC >0.06 mg/L), see flow chart below.
[1] The oxacillin 1 µg disk screen test or a benzylpenicillin MIC test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (oxacillin inhibition zone ≥20 mm, or benzylpenicillin MIC ≤0.06 mg/L) all beta-lactam agents for which clinical breakpoints are available, including those with “Note” can be reported susceptible without further testing, except for cefaclor, which if reported, should be reported as “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <20 mm, or benzylpenicillin MIC >0.06 mg/L), see flow chart below.
[1] The oxacillin 1 µg disk screen test or a benzylpenicillin MIC test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (oxacillin inhibition zone ≥20 mm, or benzylpenicillin MIC ≤0.06 mg/L) all beta-lactam agents for which clinical breakpoints are available, including those with “Note” can be reported susceptible without further testing, except for cefaclor, which if reported, should be reported as “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <20 mm, or benzylpenicillin MIC >0.06 mg/L), see flow chart below.
[1] The oxacillin 1 µg disk screen test or a benzylpenicillin MIC test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (oxacillin inhibition zone ≥20 mm, or benzylpenicillin MIC ≤0.06 mg/L) all beta-lactam agents for which clinical breakpoints are available, including those with “Note” can be reported susceptible without further testing, except for cefaclor, which if reported, should be reported as “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <20 mm, or benzylpenicillin MIC >0.06 mg/L), see flow chart below.
[1] The oxacillin 1 µg disk screen test or a benzylpenicillin MIC test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (oxacillin inhibition zone ≥20 mm, or benzylpenicillin MIC ≤0.06 mg/L) all beta-lactam agents for which clinical breakpoints are available, including those with “Note” can be reported susceptible without further testing, except for cefaclor, which if reported, should be reported as “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <20 mm, or benzylpenicillin MIC >0.06 mg/L), see flow chart below.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[1] For chloramphenicol treatment in meningitis, see table of dosages.
[1] For chloramphenicol treatment in meningitis, see table of dosages.
[B] Place the erythromycin and clindamycin disks 12-16 mm apart (edge to edge) and look for antagonism (the D phenomenon) to detect inducible clindamycin resistance. | [2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant.
[2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[A] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[B]  | [B] Isolates categorised as susceptible to norfloxacin can be reported susceptible to moxifloxacin and as "susceptible increased exposure" (I) to levofloxacin. Isolates categorised as non-susceptible should be tested for susceptibility to individual agents.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for gram positive organisms and nalidixic acid for H.influenzae and M. catarrhalis).
[E] For interpretation of the oxacillin disk screen, see flow chart below.
[1] The oxacillin 1 µg disk screen test or a benzylpenicillin MIC test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (oxacillin inhibition zone ≥20 mm, or benzylpenicillin MIC ≤0.06 mg/L) all beta-lactam agents for which clinical breakpoints are available, including those with “Note” can be reported susceptible without further testing, except for cefaclor, which if reported, should be reported as “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <20 mm, or benzylpenicillin MIC >0.06 mg/L), see flow chart below. | [2] For breakpoints and dosing in pneumonia, see table of dosages.
[1] The oxacillin 1 µg disk screen test or a benzylpenicillin MIC test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (oxacillin inhibition zone ≥20 mm, or benzylpenicillin MIC ≤0.06 mg/L) all beta-lactam agents for which clinical breakpoints are available, including those with “Note” can be reported susceptible without further testing, except for cefaclor, which if reported, should be reported as “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <20 mm, or benzylpenicillin MIC >0.06 mg/L), see flow chart below.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[A] Non-wild typeisolates were not available when developing the disk diffusion method. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Non-wild typeisolates were not available when developing the disk diffusion method. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Place the erythromycin and clindamycin disks 12-16 mm apart (edge to edge) and look for antagonism (the D phenomenon) to detect inducible clindamycin resistance. | [1] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant.
[1] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant.
[A] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. See Note 1/A on penicillins.
[A] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. See Note 1/A on penicillins.
[A] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. See Note 1/A on penicillins.
[A] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. See Note 1/A on penicillins.
[1] For susceptibility testing purposes, the concentration of relebactam is fixed at 4 mg/L. | [2] The addition of a beta-lactamase inhibitor does not add clinical benefit.
[A] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. Isolates categorised as screen negative can be reported susceptible to beta-lactam agents for which clinical breakpoints are listed (including those with “Note”). Isolates categorised as screen positive should be tested for susceptibility to individual agents.
[1] Benzylpenicillin (MIC or disk diffusion) can be used to screen for beta-lactam resistance in viridans group streptococci. Isolates categorised as screen negative can be reported susceptible to beta-lactam agents for which clinical breakpoints are listed (including those with “Note”). Isolates categorised as screen positive should be tested for susceptibility to individual agents.
[B] Non-wild type isolates were not available when developing the disk diffusion method. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[B] Non-wild type isolates were not available when developing the disk diffusion method. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] The intrinsically low activity of imipenem against Morganella morganii, Proteus spp. and Providencia spp. requires the high exposure of imipenem.
[2] The intrinsically low activity of imipenem against Morganella morganii, Proteus spp. and Providencia spp. requires the high exposure of imipenem.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] Aminopenicillin breakpoints in Enterobacterales are based on intravenous administration. For oral administration the breakpoints are relevant for urinary tract infections only. Breakpoints for other infections are under review.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars.
[3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L. | [1] Aminopenicillin breakpoints in Enterobacterales are based on intravenous administration. For oral administration the breakpoints are relevant for urinary tract infections only. Breakpoints for other infections are under review.
[3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[1] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] Aminopenicillin breakpoints in Enterobacterales are based on intravenous administration. For oral administration the breakpoints are relevant for urinary tract infections only. Breakpoints for other infections are under review.
[1] Aminopenicillin breakpoints in Enterobacterales are based on intravenous administration. For oral administration the breakpoints are relevant for urinary tract infections only. Breakpoints for other infections are under review.
[1] Aminopenicillin breakpoints in Enterobacterales are based on intravenous administration. For oral administration the breakpoints are relevant for urinary tract infections only. Breakpoints for other infections are under review.
[1] The aztreonam breakpoints for Enterobacterales will detect clinically important resistance mechanisms (including ESBL). Some isolates that produce beta-lactamases are susceptible to aztreonam with these breakpoints and should be reported as tested, i.e. the presence or absence of an ESBL does not in itself influence the categorisation of susceptibility. ESBL detection and characterisation are recommended for public health and infection control purposes.
[1] The aztreonam breakpoints for Enterobacterales will detect clinically important resistance mechanisms (including ESBL). Some isolates that produce beta-lactamases are susceptible to aztreonam with these breakpoints and should be reported as tested, i.e. the presence or absence of an ESBL does not in itself influence the categorisation of susceptibility. ESBL detection and characterisation are recommended for public health and infection control purposes.
[1] Colistin MIC determination should be performed with broth microdilution. Quality control must be performed with both a susceptible QC strain (E. coli ATCC 25922 or P. aeruginosa ATCC 27853) and the colistin resistant E. coli NCTC 13846 (mcr-1 positive).
[5] For susceptibility testing purposes, the concentration of avibactam is fixed at 4 mg/L.
[6] See table of dosages for dosing for different indications.
[7] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L. | [6] See table of dosages for dosing for different indications.
[3] Broth microdilution MIC determination must be performed in iron-depleted Mueller-Hinton broth and specific reading instructions must be followed. For testing conditions and reading instructions, see http://www.eucast.org/guidance_documents/.
[C] Zone diameter breakpoints apply to E. coli only. For other Enterobacterales, use an MIC method. | [D] Ignore isolated colonies within the inhibition zone (see pictures below).
[2] Agar dilution is the reference method for fosfomycin. MICs must be determined in the presence of glucose-6-phosphate (25 mg/L in the medium). Follow the manufacturers' instructions for commercial systems.
[4] The cefoxitin ECOFF (8 mg/L) has a high sensitivity but poor specificity for identification of AmpC-producing Enterobacterales as this agent is also affected by permeability alterations and some carbapenemases. Classical non-AmpC producers are wild type, whereas plasmid AmpC producers or chromosomal AmpC hyperproducers are non-wild type.
[A] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[1] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[3] For susceptibility testing purposes, the concentration of relebactam is fixed at 4 mg/L.
[4] For susceptibility testing purposes, the concentration of vaborbactam is fixed at 8 mg/L.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for gram positive organisms and nalidixic acid for H.influenzae and M. catarrhalis).
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] Aminopenicillin breakpoints in Enterobacterales are based on intravenous administration. For oral administration the breakpoints are relevant for urinary tract infections only. Breakpoints for other infections are under review.
[2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L. | [1] Aminopenicillin breakpoints in Enterobacterales are based on intravenous administration. For oral administration the breakpoints are relevant for urinary tract infections only. Breakpoints for other infections are under review.
[3] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[3] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[1] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[4] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[A] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[1] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[1] Colistin MIC determination should be performed with broth microdilution. Quality control must be performed with both a susceptible QC strain (E. coli ATCC 25922 or P. aeruginosa ATCC 27853) and the colistin resistant E. coli NCTC 13846 (mcr-1 positive).
[A] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[1] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[1] For susceptibility testing purposes, the concentration of relebactam is fixed at 4 mg/L.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[1] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[A] Susceptibility can be inferred from norfloxacin susceptibility. See Note
[1] Susceptibility can be inferred from ciprofloxacin susceptibility.
[C]  | [C] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance.
[A] Non-wild type isolates were not available when developing the disk diffusion method.
[A] Susceptibility can be inferred from norfloxacin susceptibility. See Note
[1] Susceptibility can be inferred from ciprofloxacin susceptibility.
[C]  | [C] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance.
[A] Non-wild type isolates were not available when developing the disk diffusion method.
[A] Read the obvious zone edge and disregard haze or growth within the inhibition zone (see pictures below). | [1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] There may be growth within the inhibition zone. The density of growth may vary from a fine haze to substantial growth (see pictures below). If any zone edge can be seen, ignore growth within the inhibition zone and read the zone diameter. | [1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Susceptibility inferred from tetracycline disk diffusion screen test.
[A] Erythromycin can be used to determine susceptibility to azithromycin and clarithromycin.
[1] Erythromycin can be used to determine susceptibility to azithromycin and clarithromycin.
[A] Tetracycline can be used to determine susceptibility to doxycycline.
[1] Tetracycline can be used to determine susceptibility to doxycycline.
[A] Erythromycin can be used to determine susceptibility to azithromycin and clarithromycin.
[1] Erythromycin can be used to determine susceptibility to azithromycin and clarithromycin.
[A] Tetracycline can be used to determine susceptibility to doxycycline.
[1] Tetracycline can be used to determine susceptibility to doxycycline.
[5] The breakpoints are based on epidemiological cut-off values (ECOFFs) and apply to oral treatment of C. difficile infections with metronidazole. There are no conclusive clinical data regarding the relation between MICs and outcomes.
[1] The breakpoints are based on epidemiological cut-off values (ECOFFs) and apply to oral treatment of C. difficile infections with vancomycin. There are no conclusive clinical data regarding the relation between MICs and outcomes.
[1] Inducible clindamycin resistance may occur in Corynebacteria. This can be detected by antagonism of clindamycin activity by a macrolide agent. The clinical significance is unknown. There is currently no recommendation for testing.
[1] Inducible clindamycin resistance may occur in Corynebacteria. This can be detected by antagonism of clindamycin activity by a macrolide agent. The clinical significance is unknown. There is currently no recommendation for testing.
[A] Non-wild typeisolates were not available when developing the disk diffusion method.
[D] Ignore isolated colonies within the inhibition zone.
[6] Agar dilution is the reference method for mecillinam MIC determination.
[A] For other Enterobacterales, the activity of tigecycline varies from insufficient in Proteus spp., Morganella morganii and Providencia spp. to variable in other species. For more information, see http://www.eucast.org/guidance_documents/. | [B] Zone diameter breakpoints validated for E. coli only. For C. koseri, use an MIC method.
[2] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [3] For other Enterobacterales, the activity of tigecycline varies from insufficient in Proteus spp., Morganella morganii and Providencia spp. to variable in other species. For more information, see http://www.eucast.org/guidance_documents/.
[D] Ignore isolated colonies within the inhibition zone.
[6] Agar dilution is the reference method for mecillinam MIC determination.
[2] Susceptibility to ampicillin, amoxicillin and piperacillin (with and without beta-lactamase inhibitor) can be inferred from ampicillin. Ampicillin resistance is uncommon in E. faecalis (confirm with MIC) but common in E. faecium. | [4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L. | [1] Aminopenicillin breakpoints in enterococci are based on intravenous administration. Oral administration is relevant for urinary tract infections only.
[A] Susceptibility to ampicillin, amoxicillin and piperacillin (with and without beta-lactamase inhibitor) can be inferred from ampicillin. Ampicillin resistance is uncommon in E. faecalis (confirm with MIC) but common in E. faecium. | [1] Aminopenicillin breakpoints in enterococci are based on intravenous administration. Oral administration is relevant for urinary tract infections only.
[2] Susceptibility to ampicillin, amoxicillin and piperacillin (with and without beta-lactamase inhibitor) can be inferred from ampicillin. Ampicillin resistance is uncommon in E. faecalis (confirm with MIC) but common in E. faecium. | [1] Aminopenicillin breakpoints in enterococci are based on intravenous administration. Oral administration is relevant for urinary tract infections only.
[2] Susceptibility to ampicillin, amoxicillin and piperacillin (with and without beta-lactamase inhibitor) can be inferred from ampicillin. Ampicillin resistance is uncommon in E. faecalis (confirm with MIC) but common in E. faecium. | [1] Aminopenicillin breakpoints in enterococci are based on intravenous administration. Oral administration is relevant for urinary tract infections only.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[B]  | [B] Susceptibility of ciprofloxacin and levofloxacin can be inferred from the norfloxacin susceptibility.
[2] Susceptibility to ampicillin, amoxicillin and piperacillin (with and without beta-lactamase inhibitor) can be inferred from ampicillin. Ampicillin resistance is uncommon in E. faecalis (confirm with MIC) but common in E. faecium. | [3] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L. | [1] Aminopenicillin breakpoints in enterococci are based on intravenous administration. Oral administration is relevant for urinary tract infections only.
[A] Vancomycin susceptible enterococci exhibit sharp zone edges and do not exhibit colonies in the inhibition zone. Examine zone edges with transmitted light (plate held up to light). If the zone edge is fuzzy, colonies grow within the zone  or if you are uncertain, then perform confirmatory testing with PCR or report resistant (see pictures below) even if the zone diameter is ≥ 12 mm. Isolates must not be reported susceptible before 24 h incubation.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[D] Ignore isolated colonies within the inhibition zone.
[6] Agar dilution is the reference method for mecillinam MIC determination.
[A] For other Enterobacterales, the activity of tigecycline varies from insufficient in Proteus spp., Morganella morganii and Providencia spp. to variable in other species. For more information, see http://www.eucast.org/guidance_documents/. | [B] Zone diameter breakpoints validated for E. coli only. For C. koseri, use an MIC method.
[2] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [3] For other Enterobacterales, the activity of tigecycline varies from insufficient in Proteus spp., Morganella morganii and Providencia spp. to variable in other species. For more information, see http://www.eucast.org/guidance_documents/.
[3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[1] Susceptibility to ampicillin, amoxicillin, piperacillin and ticarcillin can be inferred from susceptibility to benzylpenicillin.
[1] Susceptibility to ampicillin, amoxicillin, piperacillin and ticarcillin can be inferred from susceptibility to benzylpenicillin.
[1] For susceptibility testing purposes, the concentration of relebactam is fixed at 4 mg/L.
[1] Susceptibility to ampicillin, amoxicillin, piperacillin and ticarcillin can be inferred from susceptibility to benzylpenicillin.
[1] Susceptibility to ampicillin, amoxicillin, piperacillin and ticarcillin can be inferred from susceptibility to benzylpenicillin.
[2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L.
[3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[1] Susceptibility to ampicillin, amoxicillin, piperacillin and ticarcillin can be inferred from susceptibility to benzylpenicillin.
[4] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[1] Susceptibility to ampicillin, amoxicillin, piperacillin and ticarcillin can be inferred from susceptibility to benzylpenicillin.
[1] Susceptibility to ampicillin, amoxicillin, piperacillin and ticarcillin can be inferred from susceptibility to benzylpenicillin.
[1] For susceptibility testing purposes, the concentration of relebactam is fixed at 4 mg/L.
[1] Susceptibility to ampicillin, amoxicillin, piperacillin and ticarcillin can be inferred from susceptibility to benzylpenicillin.
[1] Susceptibility to ampicillin, amoxicillin, piperacillin and ticarcillin can be inferred from susceptibility to benzylpenicillin.
[2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L.
[3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[1] Susceptibility to ampicillin, amoxicillin, piperacillin and ticarcillin can be inferred from susceptibility to benzylpenicillin.
[4] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[5] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[5] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below. | [2] Beta-lactamase positive isolates can be reported resistant to ampicillin, amoxicillin and piperacillin without inhibitors. Tests based on a chromogenic cephalosporin can be used to detect the beta-lactamase.
[2] Beta-lactamase positive isolates can be reported resistant to ampicillin, amoxicillin and piperacillin without inhibitors. Tests based on a chromogenic cephalosporin can be used to detect the beta-lactamase.
[2] Beta-lactamase positive isolates can be reported resistant to ampicillin, amoxicillin and piperacillin without inhibitors. Tests based on a chromogenic cephalosporin can be used to detect the beta-lactamase.
[2] Beta-lactamase positive isolates can be reported resistant to ampicillin, amoxicillin and piperacillin without inhibitors. Tests based on a chromogenic cephalosporin can be used to detect the beta-lactamase.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[2] See table of dosages for dosing for different indications.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all carbapenems for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all cephalosporins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for cefuroxime oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all carbapenems for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all carbapenems for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[B]  | [B] Isolates categorised as susceptible to nalidixic acid can be reported susceptible to ciprofloxacin, levofloxacin, moxifloxacin and ofloxacin. Isolates categorised as non-susceptible may have fluoroquinolone resistance and should be tested against the appropriate agent.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for gram positive organisms and nalidixic acid for H.influenzae and M. catarrhalis).
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[1/A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[3] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L. | [4] Susceptibility can be inferred from amoxicillin-clavulanic acid.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all penicillins for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing, except for amoxicillin oral and amoxicillin-clavulanic acid oral, which if reported, should be reported “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <12 mm), see flow chart below. | [B] Read the outer edge of zones where an otherwise clear inhibition zone contains an area of growth around the disk, see pictures below.
[6] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[2] Susceptibility can be inferred from benzylpenicillin susceptibility.
[2] Susceptibility can be inferred from benzylpenicillin susceptibility.
[1] Susceptibility can be inferred from erythromycin susceptibility.
[1] Susceptibility can be inferred from erythromycin susceptibility.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline, but some resistant to tetracycline may be susceptible to doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[D] Ignore isolated colonies within the inhibition zone.
[6] Agar dilution is the reference method for mecillinam MIC determination.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[2] The intrinsically low activity of imipenem against Morganella morganii, Proteus spp. and Providencia spp. requires the high exposure of imipenem.
[2] The intrinsically low activity of imipenem against Morganella morganii, Proteus spp. and Providencia spp. requires the high exposure of imipenem.
[4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[A] Breakpoints relate to topical use only.
[1] Breakpoints relate to topical use only.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[A] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[B]  | [B] Isolates categorised as susceptible to nalidixic acid can be reported susceptible to ciprofloxacin, levofloxacin, moxifloxacin and ofloxacin. Isolates categorised as non-susceptible may have fluoroquinolone resistance and should be tested against the appropriate agent.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for gram positive organisms and nalidixic acid for H.influenzae and M. catarrhalis).
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L. | [3] Susceptibility can be inferred from amoxicillin-clavulanic acid.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[1] Breakpoints were determined on MICs performed on Middlebrook 7H11/7H10 medium. The comparability of tests performed by other media has not been established. There is ongoing work to review breakpoints using the EUCAST reference method (described above).
[1] Always test for beta-lactamase (tests based on a chromogenic cephalosporin can be used). If beta-lactamase positive, report resistant to ampicillin and amoxicillin. If beta-lactamase negative, determine the MIC of benzylpenicillin. Infer the susceptibility to ampicillin and amoxicillin from the benzylpenicillin MIC (do not report benzylpenicillin susceptibility).
[1] See table of dosages.
[1] Breakpoints apply only to use in the prophylaxis of meningococcal disease.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Tetracycline can be used to predict susceptibility to minocycline for prophylaxis against N. meningitidis infections.
[2] For prophylaxis of meningitis only (refer to national guidelines).
[1] Tetracycline can be used to predict susceptibility to minocycline for prophylaxis against N. meningitidis infections.
[2] The intrinsically low activity of imipenem against Morganella morganii, Proteus spp. and Providencia spp. requires the high exposure of imipenem.
[2] The intrinsically low activity of imipenem against Morganella morganii, Proteus spp. and Providencia spp. requires the high exposure of imipenem.
[D] Ignore isolated colonies within the inhibition zone.
[6] Agar dilution is the reference method for mecillinam MIC determination.
[2] The intrinsically low activity of imipenem against Morganella morganii, Proteus spp. and Providencia spp. requires the high exposure of imipenem.
[2] The intrinsically low activity of imipenem against Morganella morganii, Proteus spp. and Providencia spp. requires the high exposure of imipenem.
[A] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[1] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[1] Colistin MIC determination should be performed with broth microdilution. Quality control must be performed with both a susceptible QC strain (E. coli ATCC 25922 or P. aeruginosa ATCC 27853) and the colistin resistant E. coli NCTC 13846 (mcr-1 positive).
[2] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[1] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[1] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[1] For susceptibility testing purposes, the concentration of avibactam is fixed at 4 mg/L.
[2] See table of dosages for dosing for different indications.
[3] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L. | [2] See table of dosages for dosing for different indications.
[1] For susceptibility testing purposes, the concentration of relebactam is fixed at 4 mg/L.
[2] For susceptibility testing purposes, the concentration of vaborbactam is fixed at 8 mg/L.
[1] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note B.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note B.
[B] Isolates categorised as susceptible to nalidixic acid can be reported susceptible to ciprofloxacin and levofloxacin. Isolates categorised as non-susceptible may have fluoroquinolone resistance and should be tested against the appropriate agent.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Susceptibility inferred from tetracycline screen test.
[1] There is clinical evidence for ciprofloxacin to indicate a poor response in systemic infections caused by Salmonella spp. with low-level ciprofloxacin resistance (MIC >0.06 mg/L). The available data relate mainly to  Salmonella Typhi but there are also case reports of poor response with other Salmonella species.
[2/C] The pefloxacin 5 µg breakpoint used to screen for clinical fluoroquinolone resistance in Salmonella spp., can also be used to detect fluoroquinolone resistance mechanisms in other Enterobacterales such as E. coli, K. pneumoniae and Shigella spp. | [B]  | [B] Susceptibility of Salmonella spp. to ciprofloxacin can be inferred from pefloxacin disk diffusion susceptibility. | [1] There is clinical evidence for ciprofloxacin to indicate a poor response in systemic infections caused by Salmonella spp. with low-level ciprofloxacin resistance (MIC >0.06 mg/L). The available data relate mainly to  Salmonella Typhi but there are also case reports of poor response with other Salmonella species.
[A] There may be growth within the inhibition zone. The density of growth may vary from a fine haze to substantial growth (see pictures below). If any zone edge can be seen, ignore growth within the inhibition zone and read the zone diameter. | [1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[2] Breakpoints for nasal decontamination S ≤1, R >256 mg/L (S ≥30, R <18 mm for the mupirocin 200 µg disk). Isolates in the I category are associated with short term suppression (useful preoperatively) but, unlike fully susceptible isolates, long term eradication rates are low.
ND = No ECOFF available.
[2] Breakpoints for nasal decontamination S ≤1, R >256 mg/L (S ≥30, R <18 mm for the mupirocin 200 µg disk). Isolates in the I category are associated with short term suppression (useful preoperatively) but, unlike fully susceptible isolates, long term eradication rates are low.
ND = No ECOFF available.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for gram positive organisms and nalidixic acid for H.influenzae and M. catarrhalis).
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[B] Place the erythromycin and clindamycin disks 12-16 mm apart (edge to edge) and look for antagonism (the D phenomenon) to detect inducible clindamycin resistance. | [2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant and consider adding this comment to the report: "Clindamycin may still be used for short-term therapy of less serious skin and soft tissue infections as constitutive resistance is unlikely to develop during such therapy". The clinical importance of inducible clindamycin resistance in combination treatment of severe S. pyogenes infections is not known.
[2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant and consider adding this comment to the report: "Clindamycin may still be used for short-term therapy of less serious skin and soft tissue infections as constitutive resistance is unlikely to develop during such therapy". The clinical importance of inducible clindamycin resistance in combination treatment of severe S. pyogenes infections is not known.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[2] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturer's instructions for commercial systems. | [3] Isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] Daptomycin MICs must be determined in the presence of Ca (50 mg/L in the medium for broth dilution methods; agar dilution methods have not been validated).  Follow the manufacturer's instructions for commercial systems. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[A] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[B] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[B] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[C]  | [C] Isolates categorised as susceptible to norfloxacin can be reported susceptible to moxifloxacin and as "susceptible increased exposure" (I) to levofloxacin. Isolates categorised as non-susceptible should be tested for susceptibility to individual agents.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for gram positive organisms and nalidixic acid for H.influenzae and M. catarrhalis).
[2] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturer's instructions for commercial systems. | [3] Isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[3] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[3] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[B] Non-wild type isolates were not available when developing the disk diffusion method. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[3] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [2] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Isolates susceptible to linezolid can be reported susceptible to tedizolid. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] Isolates susceptible to linezolid can be reported susceptible to tedizolid. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[B] Non-wild type isolates were not available when developing the disk diffusion method. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturer's instructions for commercial systems. | [3] Isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturer's instructions for commercial systems. | [3] Isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] The oxacillin 1 µg disk screen test or a benzylpenicillin MIC test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (oxacillin inhibition zone ≥20 mm, or benzylpenicillin MIC ≤0.06 mg/L) all beta-lactam agents for which clinical breakpoints are available, including those with “Note” can be reported susceptible without further testing, except for cefaclor, which if reported, should be reported as “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <20 mm, or benzylpenicillin MIC >0.06 mg/L), see flow chart below. | [6] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L. | [4] Streptococcus pneumoniae do not produce beta-lactamase. The addition of a beta-lactamase inhibitor does not add clinical benefit.
[A] The oxacillin 1 µg disk screen test or a benzylpenicillin MIC test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (oxacillin inhibition zone ≥20 mm, or benzylpenicillin MIC ≤0.06 mg/L) all beta-lactam agents for which clinical breakpoints are available, including those with “Note” can be reported susceptible without further testing, except for cefaclor, which if reported, should be reported as “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <20 mm, or benzylpenicillin MIC >0.06 mg/L), see flow chart below.
[1] The oxacillin 1 µg disk screen test or a benzylpenicillin MIC test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (oxacillin inhibition zone ≥20 mm, or benzylpenicillin MIC ≤0.06 mg/L) all beta-lactam agents for which clinical breakpoints are available, including those with “Note” can be reported susceptible without further testing, except for cefaclor, which if reported, should be reported as “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <20 mm, or benzylpenicillin MIC >0.06 mg/L), see flow chart below.
[1] The oxacillin 1 µg disk screen test or a benzylpenicillin MIC test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (oxacillin inhibition zone ≥20 mm, or benzylpenicillin MIC ≤0.06 mg/L) all beta-lactam agents for which clinical breakpoints are available, including those with “Note” can be reported susceptible without further testing, except for cefaclor, which if reported, should be reported as “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <20 mm, or benzylpenicillin MIC >0.06 mg/L), see flow chart below.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[B] Place the erythromycin and clindamycin disks 12-16 mm apart (edge to edge) and look for antagonism (the D phenomenon) to detect inducible clindamycin resistance. | [2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant.
[2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[A] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[B]  | [B] Isolates categorised as susceptible to norfloxacin can be reported susceptible to moxifloxacin and as "susceptible increased exposure" (I) to levofloxacin. Isolates categorised as non-susceptible should be tested for susceptibility to individual agents.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for gram positive organisms and nalidixic acid for H.influenzae and M. catarrhalis).
[D] For interpretation of the oxacillin disk screen, see flow chart below.
[1] The oxacillin 1 µg disk screen test or a benzylpenicillin MIC test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (oxacillin inhibition zone ≥20 mm, or benzylpenicillin MIC ≤0.06 mg/L) all beta-lactam agents for which clinical breakpoints are available, including those with “Note” can be reported susceptible without further testing, except for cefaclor, which if reported, should be reported as “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <20 mm, or benzylpenicillin MIC >0.06 mg/L), see flow chart below. | [3] For breakpoints and dosing in pneumonia, see table of dosages.
[1] The oxacillin 1 µg disk screen test or a benzylpenicillin MIC test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (oxacillin inhibition zone ≥20 mm, or benzylpenicillin MIC ≤0.06 mg/L) all beta-lactam agents for which clinical breakpoints are available, including those with “Note” can be reported susceptible without further testing, except for cefaclor, which if reported, should be reported as “susceptible, increased exposure” (I). When the screen is positive (inhibition zone <20 mm, or benzylpenicillin MIC >0.06 mg/L), see flow chart below.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[A] Non-wild typeisolates were not available when developing the disk diffusion method. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Non-wild typeisolates were not available when developing the disk diffusion method. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Place the erythromycin and clindamycin disks 12-16 mm apart (edge to edge) and look for antagonism (the D phenomenon) to detect inducible clindamycin resistance. | [1] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant.
[1] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant.
[A] Benzylpenicillin 1 unit can be used to screen for beta-lactam resistance in viridans group streptococci. See Note A on penicillins.
[A] Benzylpenicillin 1 unit can be used to screen for beta-lactam resistance in viridans group streptococci. See Note A on penicillins.
[A] Benzylpenicillin 1 unit can be used to screen for beta-lactam resistance in viridans group streptococci. See Note A on penicillins.
[A] Benzylpenicillin 1 unit can be used to screen for beta-lactam resistance in viridans group streptococci. See Note A on penicillins.
[1] For susceptibility testing purposes, the concentration of relebactam is fixed at 4 mg/L.
[A] Benzylpenicillin 1 unit can be used to screen for beta-lactam resistance in viridans group streptococci. Isolates categorised as susceptible can be reported susceptible to beta-lactam agents for which clinical breakpoints are listed (including those with “Note”). Isolates categorised as non-susceptible should be tested for susceptibility to individual agents.
[B] Non-wild type isolates were not available when developing the disk diffusion method. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[B] Non-wild type isolates were not available when developing the disk diffusion method. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] Aminopenicillin breakpoints in Enterobacterales are based on intravenous administration. Breakpoints for oral administration are relevant for uncomplicated urinary tract infections only. Breakpoints for other infections are under review.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars.
[3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L. | [1] Aminopenicillin breakpoints in Enterobacterales are based on intravenous administration. Breakpoints for oral administration are relevant for uncomplicated urinary tract infections only. Breakpoints for other infections are under review.
[3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[1] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] Aminopenicillin breakpoints in Enterobacterales are based on intravenous administration. Breakpoints for oral administration are relevant for uncomplicated urinary tract infections only. Breakpoints for other infections are under review.
[1] Aminopenicillin breakpoints in Enterobacterales are based on intravenous administration. Breakpoints for oral administration are relevant for uncomplicated urinary tract infections only. Breakpoints for other infections are under review.
[1] Aminopenicillin breakpoints in Enterobacterales are based on intravenous administration. Breakpoints for oral administration are relevant for uncomplicated urinary tract infections only. Breakpoints for other infections are under review.
[1] The aztreonam breakpoints for Enterobacterales will detect clinically important resistance mechanisms (including ESBL). Some isolates that produce beta-lactamases are susceptible to aztreonam with these breakpoints and should be reported as tested, i.e. the presence or absence of an ESBL does not in itself influence the categorisation of susceptibility. ESBL detection and characterisation are recommended for public health and infection control purposes.
[1] The aztreonam breakpoints for Enterobacterales will detect clinically important resistance mechanisms (including ESBL). Some isolates that produce beta-lactamases are susceptible to aztreonam with these breakpoints and should be reported as tested, i.e. the presence or absence of an ESBL does not in itself influence the categorisation of susceptibility. ESBL detection and characterisation are recommended for public health and infection control purposes.
[1] Colistin MIC determination should be performed with broth microdilution. Quality control must be performed with both a susceptible QC strain (E. coli ATCC 25922 or P. aeruginosa ATCC 27853) and the colistin resistant E. coli NCTC 13846 (mcr-1 positive).
[3] For susceptibility testing purposes, the concentration of avibactam is fixed at 4 mg/L.
[4] See table of dosages for dosing for different indications.
[5] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L. | [4] See table of dosages for dosing for different indications.
[C] Zone diameter breakpoints apply to E. coli only. For other Enterobacterales, use an MIC method. | [D] Ignore isolated colonies within the inhibition zone (see pictures below).
[C] Zone diameter breakpoints apply to E. coli only. For other Enterobacterales, use an MIC method. | [D] Ignore isolated colonies within the inhibition zone (see pictures below).
[2] Agar dilution is the reference method for fosfomycin. MICs must be determined in the presence of glucose-6-phosphate (25 mg/L in the medium). Follow the manufacturers' instructions for commercial systems.
[2] Agar dilution is the reference method for fosfomycin. MICs must be determined in the presence of glucose-6-phosphate (25 mg/L in the medium). Follow the manufacturers' instructions for commercial systems.
[2] The cefoxitin ECOFF (8 mg/L) has a high sensitivity but poor specificity for identification of AmpC-producing Enterobacterales as this agent is also affected by permeability alterations and some carbapenemases. Classical non-AmpC producers are wild type, whereas plasmid AmpC producers or chromosomal AmpC hyperproducers are non-wild type.
[A] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[1] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[3] For susceptibility testing purposes, the concentration of relebactam is fixed at 4 mg/L.
[4] For susceptibility testing purposes, the concentration of vaborbactam is fixed at 8 mg/L.
[1] Screening agent for detection of fluoroquinolone resistance (pefloxacin for Enterobacterales, norfloxacin for gram positive organisms and nalidixic acid for H.influenzae and M. catarrhalis).
[A] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars. | [1] Aminopenicillin breakpoints in Enterobacterales are based on intravenous administration. Breakpoints for oral administration are relevant for uncomplicated urinary tract infections only. Breakpoints for other infections are under review.
[2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L. | [1] Aminopenicillin breakpoints in Enterobacterales are based on intravenous administration. Breakpoints for oral administration are relevant for uncomplicated urinary tract infections only. Breakpoints for other infections are under review.
[3] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[3] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[1] For systemic infections, aminoglycosides must be used in combination with other active therapy. In this circumstance, the breakpoint/ECOFF in brackets can be used to distinguish between organisms with and without acquired resistance mechanisms. For isolates without resistance mechanisms, include a comment in the report: “Aminoglycosides are often given in combination with other agents, either to support the activity of the aminoglycoside or to broaden the spectrum of therapy. In systemic infections, the aminoglycoside must be supported by other active therapy." For more information, see http://www.eucast.org/guidance_documents/.
[4] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[1] Colistin MIC determination should be performed with broth microdilution. Quality control must be performed with both a susceptible QC strain (E. coli ATCC 25922 or P. aeruginosa ATCC 27853) and the colistin resistant E. coli NCTC 13846 (mcr-1 positive).
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Susceptibility can be inferred from norfloxacin susceptibility. See Note
[1] Susceptibility can be inferred from ciprofloxacin susceptibility.
[C]  | [C] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance.
[A] Non-wild type isolates were not available when developing the disk diffusion method.
[A] Susceptibility can be inferred from norfloxacin susceptibility. See Note
[1] Susceptibility can be inferred from ciprofloxacin susceptibility.
[C]  | [C] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance.
[A] Non-wild type isolates were not available when developing the disk diffusion method.
[A] Read the obvious zone edge and disregard haze or growth within the inhibition zone (see pictures below). | [1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Erythromycin can be used to determine susceptibility to azithromycin and clarithromycin.
[1] Erythromycin can be used to determine susceptibility to azithromycin and clarithromycin.
[A] Tetracycline can be used to determine susceptibility to doxycycline.
[1] Tetracycline can be used to determine susceptibility to doxycycline.
[A] Erythromycin can be used to determine susceptibility to azithromycin and clarithromycin.
[1] Erythromycin can be used to determine susceptibility to azithromycin and clarithromycin.
[A] Tetracycline can be used to determine susceptibility to doxycycline.
[1] Tetracycline can be used to determine susceptibility to doxycycline.
[5] The breakpoints are based on epidemiological cut-off values (ECOFFs) and apply to oral treatment of C. difficile infections with metronidazole. There are no conclusive clinical data regarding the relation between MICs and outcomes.
[1] The breakpoints are based on epidemiological cut-off values (ECOFFs) and apply to oral treatment of C. difficile infections with vancomycin. There are no conclusive clinical data regarding the relation between MICs and outcomes.
[A] Non-wild typeisolates were not available when developing the disk diffusion method.
[A] For other Enterobacterales, the activity of tigecycline varies from insufficient in Proteus spp., Morganella morganii and Providencia spp. to variable in other species. For more information, see http://www.eucast.org/guidance_documents/. | [B] Zone diameter breakpoints validated for E. coli only. For C.koseri, use an MIC method.
[2] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [3] For other Enterobacterales, the activity of tigecycline varies from insufficient in Proteus spp., Morganella morganii and Providencia spp. to variable in other species. For more information, see http://www.eucast.org/guidance_documents/.
[5] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L. | [3] Susceptibility to ampicillin, amoxicillin and piperacillin with and without beta-lactamase inhibitor can be inferred from ampicillin.
[3] Susceptibility to ampicillin, amoxicillin and piperacillin with and without beta-lactamase inhibitor can be inferred from ampicillin.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[B]  | [B] Susceptibility of ciprofloxacin and levofloxacin can be inferred from the norfloxacin susceptibility.
[4] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L. | [3] Susceptibility to ampicillin, amoxicillin and piperacillin with and without beta-lactamase inhibitor can be inferred from ampicillin.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Vancomycin susceptible enterococci exhibit sharp zone edges and do not exhibit colonies in the inhibition zone. Examine zone edges with transmitted light (plate held up to light). If the zone edge is fuzzy, colonies grow within the zone  or if you are uncertain, then perform confirmatory testing with PCR or report resistant (see pictures below) even if the zone diameter is ≥ 12 mm. Isolates must not be reported susceptible before 24 h incubation.
[D] Ignore isolated colonies within the inhibition zone for E. coli.
[6] Agar dilution is the reference method for mecillinam MIC determination.
[A] For other Enterobacterales, the activity of tigecycline varies from insufficient in Proteus spp., Morganella morganii and Providencia spp. to variable in other species. For more information, see http://www.eucast.org/guidance_documents/. | [B] Zone diameter breakpoints validated for E. coli only. For C.koseri, use an MIC method.
[2] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [3] For other Enterobacterales, the activity of tigecycline varies from insufficient in Proteus spp., Morganella morganii and Providencia spp. to variable in other species. For more information, see http://www.eucast.org/guidance_documents/.
[3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[1] Susceptibility to ampicillin, amoxicillin, piperacillin and ticarcillin can be inferred from susceptibility to benzylpenicillin.
[1] Susceptibility to ampicillin, amoxicillin, piperacillin and ticarcillin can be inferred from susceptibility to benzylpenicillin.
[1] Susceptibility to ampicillin, amoxicillin, piperacillin and ticarcillin can be inferred from susceptibility to benzylpenicillin.
[1] Susceptibility to ampicillin, amoxicillin, piperacillin and ticarcillin can be inferred from susceptibility to benzylpenicillin.
[2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L.
[3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[1] Susceptibility to ampicillin, amoxicillin, piperacillin and ticarcillin can be inferred from susceptibility to benzylpenicillin.
[4] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[1] Susceptibility to ampicillin, amoxicillin, piperacillin and ticarcillin can be inferred from susceptibility to benzylpenicillin.
[1] Susceptibility to ampicillin, amoxicillin, piperacillin and ticarcillin can be inferred from susceptibility to benzylpenicillin.
[1] Susceptibility to ampicillin, amoxicillin, piperacillin and ticarcillin can be inferred from susceptibility to benzylpenicillin.
[1] Susceptibility to ampicillin, amoxicillin, piperacillin and ticarcillin can be inferred from susceptibility to benzylpenicillin.
[2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L.
[3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[1] Susceptibility to ampicillin, amoxicillin, piperacillin and ticarcillin can be inferred from susceptibility to benzylpenicillin.
[4] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[1] The breakpoints are based on epidemiological cut-off values (ECOFFs), which distinguish wild-type isolates from those with reduced susceptibility.
[1] The breakpoints are based on epidemiological cut-off values (ECOFFs), which distinguish wild-type isolates from those with reduced susceptibility.
[1] The breakpoints are based on epidemiological cut-off values (ECOFFs), which distinguish wild-type isolates from those with reduced susceptibility.
[1] The breakpoints are based on epidemiological cut-off values (ECOFFs), which distinguish wild-type isolates from those with reduced susceptibility.
[1] The breakpoints are based on epidemiological cut-off values (ECOFFs), which distinguish wild-type isolates from those with reduced susceptibility.
[1] The breakpoints are based on epidemiological cut-off values (ECOFFs), which distinguish wild-type isolates from those with reduced susceptibility.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all beta-lactam agents for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (inhibition zone <12 mm), see flow chart below for interpretation.
[5] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all beta-lactam agents for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (inhibition zone <12 mm), see flow chart below for interpretation. | [2] Beta-lactamase positive isolates can be reported resistant to ampicillin, amoxicillin and piperacillin without inhibitors. Tests based on a chromogenic cephalosporin can be used to detect the beta-lactamase.
[2] Beta-lactamase positive isolates can be reported resistant to ampicillin, amoxicillin and piperacillin without inhibitors. Tests based on a chromogenic cephalosporin can be used to detect the beta-lactamase.
[2] Beta-lactamase positive isolates can be reported resistant to ampicillin, amoxicillin and piperacillin without inhibitors. Tests based on a chromogenic cephalosporin can be used to detect the beta-lactamase.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all beta-lactam agents for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (inhibition zone <12 mm), see flow chart below for interpretation.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all beta-lactam agents for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (inhibition zone <12 mm), see flow chart below for interpretation. | [B] ATU relevant only if the benzylpenicillin 1 unit disk screen is positive (inhibition zone <12 mm).
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all beta-lactam agents for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (inhibition zone <12 mm), see flow chart below for interpretation.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all beta-lactam agents for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (inhibition zone <12 mm), see flow chart below for interpretation.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all beta-lactam agents for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (inhibition zone <12 mm), see flow chart below for interpretation.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all beta-lactam agents for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (inhibition zone <12 mm), see flow chart below for interpretation.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all beta-lactam agents for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (inhibition zone <12 mm), see flow chart below for interpretation. | [2] Not for meningitis (meropenem is the only carbapenem used for meningitis).
[2] Not for meningitis (meropenem is the only carbapenem used for meningitis).
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all beta-lactam agents for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (inhibition zone <12 mm), see flow chart below for interpretation. | [B] ATU relevant only if the benzylpenicillin 1 unit disk screen is positive (inhibition zone <12 mm).
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all beta-lactam agents for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (inhibition zone <12 mm), see flow chart below for interpretation. | [B] ATU relevant only if the benzylpenicillin 1 unit disk screen is positive (inhibition zone <12 mm). | [2] Not for meningitis (meropenem is the only carbapenem used for meningitis).
[2] Not for meningitis (meropenem is the only carbapenem used for meningitis).
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all beta-lactam agents for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (inhibition zone <12 mm), see flow chart below for interpretation. | [2] Not for meningitis (meropenem is the only carbapenem used for meningitis).
[2] Not for meningitis (meropenem is the only carbapenem used for meningitis).
[3] Meropenem is the only carbapenem used for meningitis.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[B]  | [B] Isolates categorised as susceptible to nalidixic acid can be reported susceptible to ciprofloxacin, levofloxacin, moxifloxacin and ofloxacin. Isolates categorised as non-susceptible may have fluoroquinolone resistance and should be tested against the appropriate agent.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[1/A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all beta-lactam agents for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (inhibition zone <12 mm), see flow chart below for interpretation.
[3] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L. | [4] Susceptibility can be inferred from amoxicillin-clavulanic acid.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[A] The benzylpenicillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥12 mm) all beta-lactam agents for which clinical breakpoints are available, including those with “Note”, can be reported susceptible without further testing. When the screen is positive (inhibition zone <12 mm), see flow chart below for interpretation.
[6] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[2] Susceptibility can be inferred from benzylpenicillin susceptibility.
[2] Susceptibility can be inferred from benzylpenicillin susceptibility.
[1] Susceptibility can be inferred from erythromycin susceptibility.
[1] Susceptibility can be inferred from erythromycin susceptibility.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline, but some resistant to tetracycline may be susceptible to doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[D] Ignore isolated colonies within the inhibition zone for E. coli.
[6] Agar dilution is the reference method for mecillinam MIC determination.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[2] The intrinsically low activity of imipenem against Morganella morganii,Proteus spp. and Providencia spp. requires the high exposure of imipenem.
[2] The intrinsically low activity of imipenem against Morganella morganii,Proteus spp. and Providencia spp. requires the high exposure of imipenem.
[4] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[A] Breakpoints relate to topical use only.
[1] Breakpoints relate to topical use only.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[A] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[B]  | [B] Isolates categorised as susceptible to nalidixic acid can be reported susceptible to ciprofloxacin, levofloxacin, moxifloxacin and ofloxacin. Isolates categorised as non-susceptible may have fluoroquinolone resistance and should be tested against the appropriate agent.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L. | [3] Susceptibility can be inferred from amoxicillin-clavulanic acid.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[2] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[1] Breakpointss apply only to tests performed on Middlebrook 7H11/7H10 medium. Comparability of tests performed by other media has not been established.
[1] Always test for beta-lactamase. If positive, report resistant to benzylpenicillin, ampicillin and amoxicillin. Tests based on a chromogenic cephalosporin can be used to detect the beta-lactamase. The susceptibility of beta-lactamase negative isolates to ampicillin and amoxicillin can be inferred from benzylpenicillin.
[1] Breakpoints apply only to use in the prophylaxis of meningococcal disease.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Tetracycline can be used to predict susceptibility to minocycline for prophylaxis against N. meningitidis infections.
[1] For prophylaxis of meningitis only (refer to national guidelines).
[1] Tetracycline can be used to predict susceptibility to minocycline for prophylaxis against N. meningitidis infections.
[2] The intrinsically low activity of imipenem against Morganella morganii,Proteus spp. and Providencia spp. requires the high exposure of imipenem.
[2] The intrinsically low activity of imipenem against Morganella morganii,Proteus spp. and Providencia spp. requires the high exposure of imipenem.
[D] Ignore isolated colonies within the inhibition zone for E. coli.
[6] Agar dilution is the reference method for mecillinam MIC determination.
[2] The intrinsically low activity of imipenem against Morganella morganii,Proteus spp. and Providencia spp. requires the high exposure of imipenem.
[2] The intrinsically low activity of imipenem against Morganella morganii,Proteus spp. and Providencia spp. requires the high exposure of imipenem.
[1] Colistin MIC determination should be performed with broth microdilution. Quality control must be performed with both a susceptible QC strain (E. coli ATCC 25922 or P. aeruginosa ATCC 27853) and the colistin resistant E. coli NCTC 13846 (mcr-1 positive).
[2] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[1] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[1] For susceptibility testing purposes, the concentration of avibactam is fixed at 4 mg/L.
[2] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[1] For susceptibility testing purposes, the concentration of vaborbactam is fixed at 8 mg/L.
[1] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note B.
[A] The nalidixic acid disk diffusion test can be used to screen for fluoroquinolone resistance. See Note B.
[B] Isolates categorised as susceptible to nalidixic acid can be reported susceptible to ciprofloxacin and levofloxacin. Isolates categorised as non-susceptible may have fluoroquinolone resistance and should be tested against the appropriate agent.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Susceptibility inferred from tetracycline screen test.
[1] There is clinical evidence for ciprofloxacin to indicate a poor response in systemic infections caused by Salmonella spp. with low-level ciprofloxacin resistance (MIC >0.06 mg/L). The available data relate mainly to  Salmonella Typhi but there are also case reports of poor response with other Salmonella species.
[B]  | [B] Susceptibility of Salmonella spp. to ciprofloxacin can be inferred from pefloxacin disk diffusion susceptibility. | [1] There is clinical evidence for ciprofloxacin to indicate a poor response in systemic infections caused by Salmonella spp. with low-level ciprofloxacin resistance (MIC >0.06 mg/L). The available data relate mainly to  Salmonella Typhi but there are also case reports of poor response with other Salmonella species.
[A] Isolates showing any sign of inhibition zone ≥ 16 mm should be reported susceptible and growth within the inhibition zone should be ignored. The density of growth within the zone may vary from a fine haze to substantial growth (see pictures below). | [1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[B] Place the erythromycin and clindamycin disks 12-16 mm apart (edge to edge) and look for antagonism (the D phenomenon) to detect inducible clindamycin resistance. | [2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant and consider adding this comment to the report: "Clindamycin may still be used for short-term therapy of less serious skin and soft tissue infections as constitutive resistance is unlikely to develop during such therapy". The clinical importance of inducible clindamycin resistance in combination treatment of severe S. pyogenes infections is not known.
[2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant and consider adding this comment to the report: "Clindamycin may still be used for short-term therapy of less serious skin and soft tissue infections as constitutive resistance is unlikely to develop during such therapy". The clinical importance of inducible clindamycin resistance in combination treatment of severe S. pyogenes infections is not known.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[2] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturer's instructions for commercial systems. | [3] Isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] Daptomycin MICs must be determined in the presence of Ca (50 mg/L in the medium for broth dilution methods; agar dilution methods have not been validated).  Follow the manufacturer's instructions for commercial systems. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[A] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[B]  | [B] Isolates categorised as susceptible to norfloxacin can be reported susceptible to levofloxacin and moxifloxacin. Isolates categorised as non-susceptible should be tested for susceptibility to individual agents.
[2] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturer's instructions for commercial systems. | [3] Isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[3] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[3] Trimethoprim-sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[B] Non-wild type isolates were not available when developing the disk diffusion method. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[3] For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use. | [2] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] Isolates susceptible to linezolid can be reported susceptible to tedizolid. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[B] Non-wild type isolates were not available when developing the disk diffusion method. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturer's instructions for commercial systems. | [3] Isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[2] MICs must be determined in the presence of polysorbate-80 (0.002% in the medium for broth dilution methods; agar dilution methods have not been validated). Follow the manufacturer's instructions for commercial systems. | [3] Isolates susceptible to vancomycin can be reported susceptible to dalbavancin and oritavancin. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] The oxacillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥20 mm) all beta-lactam agents for which clinical breakpoints are available, including those with “Note” can be reported susceptible without further testing. When the screen is positive (inhibition zone <20 mm), see flow chart below for interpretation. | [5] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] The oxacillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥20 mm) all beta-lactam agents for which clinical breakpoints are available, including those with “Note” can be reported susceptible without further testing. When the screen is positive (inhibition zone <20 mm), see flow chart below for interpretation.
[1] The oxacillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥20 mm) all beta-lactam agents for which clinical breakpoints are available, including those with “Note” can be reported susceptible without further testing. When the screen is positive (inhibition zone <20 mm), see flow chart below for interpretation.
[1] The oxacillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥20 mm) all beta-lactam agents for which clinical breakpoints are available, including those with “Note” can be reported susceptible without further testing. When the screen is positive (inhibition zone <20 mm), see flow chart below for interpretation.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[B] Place the erythromycin and clindamycin disks 12-16 mm apart (edge to edge) and look for antagonism (the D phenomenon) to detect inducible clindamycin resistance. | [2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant.
[2] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[A] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[2] Not for meningitis (meropenem is the only carbapenem used for meningitis).
[2] Not for meningitis (meropenem is the only carbapenem used for meningitis).
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[2] Not for meningitis (meropenem is the only carbapenem used for meningitis).
[3] Meropenem is the only carbapenem used for meningitis.
[A] The norfloxacin disk diffusion test can be used to screen for fluoroquinolone resistance. See Note
[A] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[B]  | [B] Isolates categorised as susceptible to norfloxacin can be reported susceptible to levofloxacin and moxifloxacin. Isolates categorised as non-susceptible should be tested for susceptibility to individual agents.
[D] For interpretation of the oxacillin disk screen, see flow chart below.
[1] The oxacillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥20 mm) all beta-lactam agents for which clinical breakpoints are available, including those with “Note” can be reported susceptible without further testing. When the screen is positive (inhibition zone <20 mm), see flow chart below for interpretation. | [3] For breakpoints and dosing in pneumonia, see table of dosages.
[1] The oxacillin 1 unit disk screen test shall be used to exclude beta-lactam resistance mechanisms. When the screen is negative (inhibition zone ≥20 mm) all beta-lactam agents for which clinical breakpoints are available, including those with “Note” can be reported susceptible without further testing. When the screen is positive (inhibition zone <20 mm), see flow chart below for interpretation.
[1] Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[1] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[A] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[1] Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant to tetracycline may be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility of tetracycline resistant isolates if required.
[A] Non-wild typeisolates were not available when developing the disk diffusion method. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Non-wild typeisolates were not available when developing the disk diffusion method. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Place the erythromycin and clindamycin disks 12-16 mm apart (edge to edge) and look for antagonism (the D phenomenon) to detect inducible clindamycin resistance. | [1] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant.
[1] Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent. If not detected, then report as tested according to the clinical breakpoints. If detected, then report as resistant.
[A] Benzylpenicillin 1 unit can be used to screen for beta-lactam resistance in viridans group streptococci. See Note A on penicillins.
[A] Benzylpenicillin 1 unit can be used to screen for beta-lactam resistance in viridans group streptococci. See Note A on penicillins.
[A] Benzylpenicillin 1 unit can be used to screen for beta-lactam resistance in viridans group streptococci. See Note A on penicillins.
[A] Benzylpenicillin 1 unit can be used to screen for beta-lactam resistance in viridans group streptococci. See Note A on penicillins.
[A] Benzylpenicillin 1 unit can be used to screen for beta-lactam resistance in viridans group streptococci. Isolates categorised as susceptible can be reported susceptible to beta-lactam agents for which clinical breakpoints are listed (including those with “Note”). Isolates categorised as non-susceptible should be tested for susceptibility to individual agents.
[B] Non-wild type isolates were not available when developing the disk diffusion method. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[B] Non-wild type isolates were not available when developing the disk diffusion method. | [1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[1] Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test result on any such isolate must be confirmed and the isolate sent to a reference laboratory.
[A] Wild type Enterobacterales are categorised as susceptible to aminopenicillins. 
Some countries prefer to categorise wild-type isolates of E. coli and P. mirabilis as "Susceptible, increased exposure". When this is the case, use the MIC breakpoint S ≤ 0.5 mg/L and the corresponding zone diameter breakpoint S ≥ 50 mm. | [B] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars.
[A] Wild type Enterobacterales are categorised as susceptible to aminopenicillins. 
Some countries prefer to categorise wild-type isolates of E. coli and P. mirabilis as "Susceptible, increased exposure". When this is the case, use the MIC breakpoint S ≤ 0.5 mg/L and the corresponding zone diameter breakpoint S ≥ 50 mm. | [B] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars.
[1] Wild type Enterobacterales are categorised as susceptible to aminopenicillins. 
Some countries prefer to categorise wild-type isolates of E. coli and P. mirabilis as "Susceptible, increased exposure". When this is the case, use the MIC breakpoint S ≤ 0.5 mg/L and the corresponding zone diameter breakpoint S ≥ 50 mm. | [3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[1] Wild type Enterobacterales are categorised as susceptible to aminopenicillins. 
Some countries prefer to categorise wild-type isolates of E. coli and P. mirabilis as "Susceptible, increased exposure". When this is the case, use the MIC breakpoint S ≤ 0.5 mg/L and the corresponding zone diameter breakpoint S ≥ 50 mm. | [3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[A] Wild type Enterobacterales are categorised as susceptible to aminopenicillins. 
Some countries prefer to categorise wild-type isolates of E. coli and P. mirabilis as "Susceptible, increased exposure". When this is the case, use the MIC breakpoint S ≤ 0.5 mg/L and the corresponding zone diameter breakpoint S ≥ 50 mm. | [B] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars.
[1] Wild type Enterobacterales are categorised as susceptible to aminopenicillins. 
Some countries prefer to categorise wild-type isolates of E. coli and P. mirabilis as "Susceptible, increased exposure". When this is the case, use the MIC breakpoint S ≤ 0.5 mg/L and the corresponding zone diameter breakpoint S ≥ 50 mm.
[1] Wild type Enterobacterales are categorised as susceptible to aminopenicillins. 
Some countries prefer to categorise wild-type isolates of E. coli and P. mirabilis as "Susceptible, increased exposure". When this is the case, use the MIC breakpoint S ≤ 0.5 mg/L and the corresponding zone diameter breakpoint S ≥ 50 mm.
[1] The aztreonam breakpoints for Enterobacterales will detect clinically important resistance mechanisms (including ESBL). Some isolates that produce beta-lactamases are susceptible to aztreonam with these breakpoints and should be reported as tested, i.e. the presence or absence of an ESBL does not in itself influence the categorisation of susceptibility. ESBL detection and characterisation are recommended for public health and infection control purposes.
[1] The aztreonam breakpoints for Enterobacterales will detect clinically important resistance mechanisms (including ESBL). Some isolates that produce beta-lactamases are susceptible to aztreonam with these breakpoints and should be reported as tested, i.e. the presence or absence of an ESBL does not in itself influence the categorisation of susceptibility. ESBL detection and characterisation are recommended for public health and infection control purposes.
[1] Colistin MIC determination should be performed with broth microdilution. Quality control must be performed with both a susceptible QC strain (E. coli ATCC 25922 or P. aeruginosa ATCC 27853) and the colistin resistant E. coli NCTC 13846 (mcr-1 positive).
[3] For susceptibility testing purposes, the concentration of avibactam is fixed at 4 mg/L.
[4] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.
[C] Zone diameter breakpoints apply to E. coli only. For other Enterobacterales, use an MIC method. | [D] Ignore isolated colonies within the inhibition zone (see pictures below).
[C] Zone diameter breakpoints apply to E. coli only. For other Enterobacterales, use an MIC method. | [D] Ignore isolated colonies within the inhibition zone (see pictures below).
[2] Agar dilution is the reference method for fosfomycin. MICs must be determined in the presence of glucose-6-phosphate (25 mg/L in the medium). Follow the manufacturers' instructions for commercial systems.
[2] Agar dilution is the reference method for fosfomycin. MICs must be determined in the presence of glucose-6-phosphate (25 mg/L in the medium). Follow the manufacturers' instructions for commercial systems.
[2] The cefoxitin ECOFF (8 mg/L) has a high sensitivity but poor specificity for identification of AmpC-producing Enterobacterales as this agent is also affected by permeability alterations and some carbapenemases. Classical non-AmpC producers are wild type, whereas plasmid AmpC producers or chromosomal AmpC hyperproducers are non-wild type.
[3] For susceptibility testing purposes, the concentration of vaborbactam is fixed at 8 mg/L.
[A] Wild type Enterobacterales are categorised as susceptible to aminopenicillins. 
Some countries prefer to categorise wild-type isolates of E. coli and P. mirabilis as "Susceptible, increased exposure". When this is the case, use the MIC breakpoint S ≤ 0.5 mg/L and the corresponding zone diameter breakpoint S ≥ 50 mm. | [B] Ignore growth that may appear as a thin inner zone on some batches of Mueller-Hinton agars.
[1] Wild type Enterobacterales are categorised as susceptible to aminopenicillins. 
Some countries prefer to categorise wild-type isolates of E. coli and P. mirabilis as "Susceptible, increased exposure". When this is the case, use the MIC breakpoint S ≤ 0.5 mg/L and the corresponding zone diameter breakpoint S ≥ 50 mm. | [2] For susceptibility testing purposes, the concentration of sulbactam is fixed at 4 mg/L.
[3] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[3] Trimethoprim:sulfamethoxazole in the ratio 1:19. Breakpoints are expressed as the trimethoprim concentration.
[3] For susceptibility testing purposes, the concentration of clavulanic acid is fixed at 2 mg/L.
[4] For susceptibility testing purposes, the concentration of tazobactam is fixed at 4 mg/L.