TABLE 4.

MICs of β-lactams for E. coli XL-1 (pBC-SIM1), expressing the SIM-1 enzyme, and for the E. coli host containing only the cloning vector pBC-SK

AntibioticMIC (μg/ml)
XL-1(pBC-SIM1)XL-1(pBC-SK)
Ampicillin642
Ticarcillin>1284
Piperacillin11
Cephalothin>1284
Cefoxitin>1282
Cefuroxime>1284
Cefotaxime32≤0.06
Ceftriaxone32≤0.06
Ceftazidime320.12
Cefepime2≤0.06
Imipenem10.12
Meropenem2≤0.06
Panipenem20.12
Aztreonam0.250.25
Carbapenemase sp act (nmol imipenem/min/mg protein)2,800 ± 400a<1
  • a The carbapenemase activity was reduced by 80% after incubation of the extract with 5 mM EDTA for 20 min at 25°C.