TABLE 4.
Etest MICs of β-lactam antibiotics against E. coli DH5α clones producing GES variants under isogenic conditions
| Inhibitor | MIC (μg/ml) |
||||||
|---|---|---|---|---|---|---|---|
| E. coli (GES-1 [E104, G170]) | E. coli (GES-7 [K104, G170]) | E. coli (GES-2 [E104, N170]) | E. coli (GES-5 [E104, S170]) | E. coli (GES-6 [K104, S170]) | E. coli (GES-13 [K104, N170]) | E. coli DH5α | |
| Ampicillin | >256 | >256 | >256 | >256 | >256 | >256 | 2 |
| Amoxicillin-clavulanic acida | 8 | 32 | 3 | 16 | 32 | 3 | 2 |
| Ticarcillin | >256 | >256 | >256 | >256 | >256 | >256 | 4 |
| Ticarcillin-clavulanic acidb | 6 | >256 | 1.5 | 16 | >256 | 8 | 4 |
| Piperacillin | 8 | 12 | 4 | 8 | 12 | 8 | 2 |
| Piperacillin-tazobactamc | 1 | 1 | 1 | 2 | 2 | 1 | 1 |
| Cefoxitin | 3 | 3 | 3 | 16 | 48 | 3 | 2 |
| Ceftazidime | 8 | >256 | 0.5 | 0.75 | 4 | 32 | 0.12 |
| Aztreonam | 0.094 | 2 | 0.032 | 0.032 | 0.094 | 2 | 0.032 |
| Cefotaxime | 1 | 1.5 | 0.75 | 0.125 | 0.125 | 3 | 0.032 |
| Imipenem | 0.25 | 0.125 | 0.50 | 1.5 | 0.50 | 0.25 | 0.064 |
| Meropenem | 0.016 | 0.016 | 0.032 | 0.094 | 0.047 | 0.023 | 0.008 |
a
Penicillin/inhibitor ratio of 2:1.
b
Inhibitor was present at a fixed concentration of 2 μg/ml.
c
Inhibitor was present at a fixed concentration of 4 μg/ml.