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Table 1 Interpretive criteria for E coli using broth microdilution susceptibility testing reported as minimum inhibitory concentrations (μg/ml)

From: Methodological comparisons for antimicrobial resistance surveillance in feedlot cattle

Antimicrobial Susceptible Intermediate Resistant Reference
Amikacin ≤16 32 ≥64 CLSI M100-S22, 2012
Ampicillin ≤8 16 ≥32 CLSI M100-S22, 2012
Amoxicillin-Clavulanate ≤8/4 16/8 ≥32/16 CLSI M100-S22, 2012
Cefoxitin ≤8 16 ≥32 CLSI M100-S22, 2012
Ceftiofur ≤2 4 ≥8 CLSI M31-A4, 2013
Ceftriaxone ≤1 2 ≥4 CLSI M100-S22, 2012
Chloramphenicol ≤8 16 ≥32 CLSI M100-S22, 2012
Ciprofloxacin ≤1 2 ≥4 CLSI M100-S21, 2011
Gentamicin ≤4 8 ≥16 CLSI M100-S22, 2012
Kanamycin ≤16 32 ≥64 CLSI M100-S22, 2012
Nalidixic Acid ≤16 - ≥32 CLSI M100-S22, 2012
Streptomycin ≤32 - ≥64 NARMS Executive Report 2009
Sulfisoxazole ≤256 - ≥512 CLSI M100-S22, 2012
Tetracycline ≤4 8 ≥16 CLSI M100-S22, 2012
Trimethoprim-Sulfamethoxazole ≤2/38 - ≥4/76 CLSI M100-S22, 2012
  1. CLSI = Clinical and Laboratory Standards Institute.
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