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
| Antibiotic | MIC (μg/ml)
|
|
|---|---|---|
| XL-1(pBC-SIM1) | XL-1(pBC-SK) | |
| Ampicillin | 64 | 2 |
| Ticarcillin | >128 | 4 |
| Piperacillin | 1 | 1 |
| Cephalothin | >128 | 4 |
| Cefoxitin | >128 | 2 |
| Cefuroxime | >128 | 4 |
| Cefotaxime | 32 | ≤0.06 |
| Ceftriaxone | 32 | ≤0.06 |
| Ceftazidime | 32 | 0.12 |
| Cefepime | 2 | ≤0.06 |
| Imipenem | 1 | 0.12 |
| Meropenem | 2 | ≤0.06 |
| Panipenem | 2 | 0.12 |
| Aztreonam | 0.25 | 0.25 |
| 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.