Table 1.

Antimicrobial resistance phenotypes of bovineE. coli isolates

Class and/or antimicrobial% Resistant strainsa (n = 48)
Phenicols
 Florfenicolb 92
 Chloramphenicol90
Penicillins
 Ampicillin88
 Amoxicillin-clavulanic acid69
Cephalosporins
 Cephalothin77
 Ceftiofur69
 Ceftriaxone15
Tetracycline100
Aminoglycosides
 Amikacin0
 Apramycin8
 Gentamicin63
 Kanamycin92
 Streptomycin100
Sulfonamides and potentiated sulfonamides
 Sulfamethoxazole100
 Trimethoprim-sulfamethoxazole69
Quinolones and fluoroquinolones
 Nalidixic acid8
 Ciprofloxacin0
  • a MICs were determined via microdilution methods according to NCCLS standards (24, 25).

  • b Resistance based on NCCLS breakpoint for bovine respiratory pathogens, ≥8 μg/ml (25).