TABLE 2.
MICs (determined by Etest) of several β-lactam and non-β-lactam antibiotics for the epidemic CTX-M-1-producing multiresistant K. pneumoniae strain, the two carbapenem-resistant mutants, and the E. coli transformant harboring the CTX-M-1-encoding plasmid pAMR-1
| Antibiotic | MIC (μg/ml) for:
|
||||
|---|---|---|---|---|---|
| CTX-M-1-producing K. pneumoniae epidemic straina |
K. pneumoniae carbapenem-resistant mutants
|
E. coli XL1-Blue | E. coli XL1-Blue (pAMR-1) | ||
| KpCR-1 | KpCR-2 | ||||
| Ampicillin | >256 | >256 | >256 | 4 | >256 |
| Amoxycilin + clavulanate | 16-32 | >256 | 32 | 4 | 16 |
| Ticarcillin | >256 | >256 | >256 | 8 | >256 |
| Piperacillin | >256 | >256 | >256 | 1.5 | >256 |
| Piperacillin + tazobactam | 32->256 | >256 | >256 | 1.5 | 16 |
| Cefoxitin | 6-48 | >256 | 128 | 2 | 8 |
| Ceftazidime | 16-128 | >256 | >256 | 0.5 | 24 |
| Ceftazidime + clavulanate | 1.5-4 | >4 | >4 | 0.5 | 2 |
| Cefotaxime | >256 | >256 | >256 | 0.19 | >256 |
| Cefotaxime + calvulanate | 0.38-1 | >1 | >1 | <0.25 | 0.5 |
| Cefepime | 32->256 | >256 | >256 | 0.125 | 128 |
| Cefepime + clavulanate | 0.094-0.5 | >4 | >4 | 0.094 | 0.19 |
| Aztreonam | 48->256 | >256 | >256 | 0.125 | >256 |
| Imipenem | 0.38-0.5 | 8 | 12 | 0.38 | 0.38 |
| Meropenem | 0.094-0.25 | 16 | 16 | 0.016 | 0.047 |
| Ertapenem | 0.094-1.5 | >32 | >32 | 0.012 | 0.125 |
| Gentamicin | 12-24 | 32 | 48 | 0.19 | 8 |
| Tobramycin | 16-32 | 48 | 96 | 0.125 | 16 |
| Amikacin | 1.5-3 | 3 | 6 | 0.75 | 0.75 |
| Ciprofloxacin | >32 | >32 | >32 | 0.047 | 0.047 |
| Trimethoprim + sulfamethoxazole | >32 | >32 | >32 | 0.012 | 0.032 |
| Tetracyclines | >256 | >256 | >256 | >256 | >256 |
a
Range of MICs for five randomly selected isolates, each recovered from a different patient at different periods of the outbreak.