Table 1.

MICS of β-lactams

AntibioticMIC (μg/ml)a
A. baumannii RYC 52763/97E. coli TG1E. coli TG1 (pGER1)E. coli TG1 (pGER2)
Ampicillin>1,0244128>1,024
Ampicillin plus clavulanic acidb>1,024464128
Ampicillin plus sulbactamb>1,024216>1,024
Ampicillin plus tazobactamb>1,02423264
Ticarcillin>1,024432>1,024
Cefazolin>2568>256>256
Cefuroxime>2564>256>256
Cefoxitin>256444
Cefotaxime>256≤0.12548
Cefotaxime plus clavulanic acid>256≤0.12524
Cefotaxime plus sulbactam>256≤0.1250.252
Cefotaxime plus tazobactam>256≤0.1250.51
Ceftazidime>256≤0.1251632
Ceftazidime plus clavulanic acid>256≤0.125816
Ceftazidime plus sulbactam>256≤0.12518
Ceftazidime plus tazobactam>256≤0.12524
Cefepime256≤0.1250.250.5
Aztreonam>256≤0.12514
Imipenem1280.250.250.25
Meropenem2560.030.030.03
  • a Enzymes are as follows: for A. baumannii RYC 52763/97, AmpC plus a β-lactamase with a pI of 9.0 plus TEM-1; for E. coli TG1(pGER1), AmpC; and forE. coli TG1(pGER2), AmpC plus TEM-1. Clone E. coli TG1(pGER2) harbored the ampC gene in the pUC18 multicopy plasmid (containing the blaTEM-1resistance marker).

  • b Concentration of β-lactamase inhibitor was 4 μg/ml.