TABLE 1.

MICs of antimicrobial agents for clinical isolate S. enterica Typhimurium N02-114, transconjugant E. coli N02114M, and E. coli J53-2

Beta-lactam(s)aMIC (μg/ml)b
S. enterica Typhimurium N02-114 (TEM-1, SHV-2a)E. coli N02114M (SHV-2a)E. coli J53-2
Ampicillin>32>32≤2
Cephalothin>32>328
Ceftiofur1616≤0.5
Amoxicillin + CLA884
Cefpodoxime>16>16≤0.25
Cefpodoxime + CLA≤0.25≤0.25≤0.25
Ceftriaxone>1616≤0.25
Ceftriaxone + CLA≤0.25≤0.25≤0.25
Cefotaxime >16 16 ≤0.25
Cefotaxime + CLA ≤0.25 ≤0.25 ≤0.25
Ceftazidime >16 2 ≤0.25
Ceftazidime + CLA 0.5 ≤0.25 ≤0.25
Aztreonam80.5≤0.25
Aztreonam + CLA≤0.25≤0.25≤0.25
Cefipime8≤0.5≤0.25
Cefoxitin442
Meropenem≤0.25≤0.25≤0.25
Amikacin≤4≤4≤4
Apramycin≤2≤2≤2
Chloramphenicol≤488
Trimethoprim-sulfamethoxazole>4/76>4/76≤1.2/2.3
Nalidixic acid≤4<4≤4
Ciprofloxacin≤0.015≤0.015≤0.015
Gentamicin0.50.5≤0.25
Kanamycin>64≤16≤16
Streptomycin256<32<32
Tetracycline>32>328
  • a CLA, clavulanic acid at a fixed concentration of 4 μg/ml.

  • b The NCCLS ESBL-positive breakpoints for E. coli and Klebsiella spp. are shown in bold type.