Table 1. MICs of β-lactams of the CTX-M-94- and -100-producing E. coli, E. coli TOP10 transformed with wild-type pCR-CTX-M-94 and -100 and mutagenized pCR-CTX-M-94 and -100.
| Antibiotics | Minimum inhibitory concentrations (mg/L) | |||||||
| E. coli | E. coli | pCR-CTX-M-94 | pCR-CTX-M-94 | pCR-CTX-M-94 | pCR-CTX-M-100 | pCR-CTX-M-100 | pCR-CTX-M-100 | |
| (clinical isolate) | (clinical isolate) | (wild type) | (mutagenized) | (mutagenized) | (wild type) | (mutagenized) | (mutagenized) | |
| (CTX-M-94, TEM-1, CMY-2) | (CTX-M-100) | (A77, L119, G240) | (V77, L119, G240) | (A77, L119, D240) | (A77, F119, G240) | (V77, F119, G240) | (A77, F119, D240) | |
| ( = CTX-M-25) | ( = CTX-M-39) | |||||||
| Amoxicillin | >256* | >256* | >256* | >256* | >256* | >256* | >256* | >256* |
| Amoxicillin/clavulanate | 8** | 2 | 3 | 3 | 3 | 3 | 3 | 3 |
| Ampicillin | >256* | >256* | >256* | >256* | >256* | >256* | >256* | >256* |
| Aztreonam | 6** | 2 | 4 | 4 | 1.50 | 4 | 4 | 1.50 |
| Cefepime | 8 | 1.50 | 2 | 2 | 1.50 | 2 | 2 | 1 |
| Cefotaxime | >256* | 12* | 16* | 16* | 4* | 16* | 24* | 1.50** |
| Cefoxitin | >256* | 1.50 | 2 | 4 | 1 | 2 | 4 | 1.50 |
| Ceftazidime | 12–16** | 1.50 | 4 | 4 | 0.50 | 3 | 3 | 0.38 |
| Ceftazidime/clavulanate | >4 | 0.06 | 0.25 | 0.25 | 0.19 | 0.25 | 0.25 | 0.19 |
| Ceftriaxone | >256* | 8* | 48* | 24* | 12* | 12* | 32* | 4* |
| Imipenem | 0.75–1.50 | 1.50 | 0.38 | 0.38 | 0.38 | 0.25 | 0.25 | 0.38 |
| Piperacillin | >256* | >256* | >256* | >256* | >256* | >256* | >256* | 64** |
| Piperacillin/tazobactam | 0.75 | 0.50 | 1.50 | 1 | 1 | 1.50 | 2 | 1.50 |
*
Indicates high-level resistance.
**
Indicates intermediate resistance.