TABLE 3.
MICs of various antibiotics conferred by mutant TEM β-lactamases
| Amino acid replacement(s) | MIC (μg/ml)a
|
|||||||
|---|---|---|---|---|---|---|---|---|
| AMP | PIP | CAZ | FEP | CRO | CTX | ATM | IPM | |
| E. coli JM83b | 4 | 1 | 0.06 | 0.03 | 0.03 | 0.03 | 0.03 | 0.12 |
| TEM-1 (none)c | 16,000 | 4,000 | 0.5 | 0.25 | 0.06 | 0.06 | 0.12 | 0.12 |
| E104K | 16,000 | 2,000 | 2 | 0.5 | 0.25 | 0.25 | 0.5 | 0.12 |
| S268G | 16,000 | 4,000 | 0.5 | 0.5 | 0.12 | 0.12 | 0.12 | 0.12 |
| N276D | 16,000 | 4,000 | 0.5 | 0.25 | 0.03 | 0.03 | 0.06 | 0.12 |
| E104K, S268G | 16,000 | 4,000 | 4 | 2 | 1 | 1 | 1 | 0.12 |
| E104K, N276D | 16,000 | 2,000 | 4 | 1 | 0.06 | 0.06 | 0.25 | 0.12 |
| S268G, N276D | 16,000 | 4,000 | 1 | 0.5 | 0.03 | 0.03 | 0.06 | 0.12 |
| E104K, S268G, N276D | 16,000 | 4,000 | 8 | 2 | 0.12 | 0.12 | 0.25 | 0.12 |
| A42G, I47V, E104K, S268G, N276D | 32,000 | 8,000 | 16 | 4 | 0.25 | 0.25 | 0.5 | 0.12 |
a
Abbreviations: AMP, ampicillin; PIP, piperacillin; CAZ, ceftazidime; FEP, cefepime; CRO, ceftriaxone; CTX, cefotaxime; ATM, aztreonam; IPM, imipenem.
b
Recipient strain E. coli JM83.
c
Wild-type TEM-1 β-lactamase.