TABLE 1.
Antimicrobial agent | Result for method:
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---|---|---|---|---|---|---|---|---|
Agar dilution
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Disk diffusion
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Test range (μg/ml) | MIC breakpoint (μg/ml)a
|
Disk concn (μg) | Zone diam breakpoint (mm)b
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S | I | R | S | I | R | |||
Ampicillin | 0.06-128 | ≤8 | 16 | ≥32 | 10 | ≥17 | 14-16 | ≤13 |
Tetracycline | 0.06-128 | ≤4 | 8 | ≥16 | 30 | ≥19 | 15-18 | ≤14 |
Gentamicin | 0.06-128 | ≤4 | 8 | ≥16 | 10 | ≥15 | 13-14 | ≤12 |
Kanamycin | 0.25-128 | ≤16 | 32 | ≥64 | 30 | ≥18 | 14-17 | ≤13 |
Clindamycin | 0.06-128 | ≤0.5 | 1-2 | ≥4 | 2 | ≥21 | 15-20 | ≤14 |
Erythromycin | 0.06-128 | ≤0.5 | 1-4 | ≥8 | 15 | ≥23 | 14-22 | ≤13 |
Ciprofloxacin | 0.008-128 | ≤1 | 2 | ≥4 | 5 | ≥21 | 16-20 | ≤15 |
Norfloxacin | 0.06-128 | ≤4 | 8 | ≥16 | 10 | ≥17 | 13-16 | ≤12 |
Nalidixic acid | 0.25-128 | ≤16 | ≥32 | 30 | ≥19 | 14-18 | ≤13 |
MIC breakpoints for enteric bacteria from the NARMS were used for all antimicrobial agents except norfloxacin. MIC breakpoints for Enterobacteriaceae for norfloxacin were recommended by the CLSI (formerly NCCLS). S, susceptible; I, intermediate; R, resistant.
Zone diameter breakpoints of ampicillin, tetracycline, gentamicin, kanamycin, clindamycin, and erythromycin for bacteria isolated from animals were recommended by the CLSI. Zone diameter breakpoints of ciprofloxacin, norfloxacin, and nalidixic acid for Enterobacteriaceae were recommended by the CLSI. S, susceptible; I, intermediate; R, resistant.