TABLE 4.
Susceptibilities of E. coli JM83 producing TEM-1 and its mutants to β-lactams and to β-lactam-β-lactamase inhibitor combinations
| Amino acid replacement(s) | MICs (μg/ml)a
|
|||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| AMP | AMP + CLA2 | AMP + CLA4 | AMP + TAZ4 | AMP + TAZ8 | AMP + TAZ16 | PIP | PIP + TAZ4 | PIP + TAZ8 | PIP + TAZ16 | CAZ | CAZ + CLA2 | CAZ + CLA4 | CAZ + TAZ4 | CAZ + TAZ8 | CAZ + TAZ16 | |
| TEM-1 (none)b | 16,000 | 250 | 64 | 4,000 | 2,000 | <32 | 4,000 | 1,000 | 500 | <16 | 0.5 | 0.25 | 0.25 | 0.5 | 0.5 | 0.06 |
| E104K | 16,000 | 64 | 16 | 2,000 | 500 | <32 | 2,000 | 500 | 32 | <16 | 2 | 0.5 | 0.5 | 1 | 1 | 0.12 |
| S268G | 16,000 | 250 | 125 | 4,000 | 2,000 | <32 | 4,000 | 2,000 | 500 | <16 | 0.5 | 0.25 | 0.25 | 0.5 | 0.5 | 0.06 |
| N276D | 16,000 | 2,000 | 500 | 4,000 | 2,000 | <32 | 4,000 | 1,000 | 500 | <16 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.06 |
| E104K, S268G | 16,000 | 125 | 64 | 4,000 | 1,000 | <32 | 4,000 | 2,000 | 500 | <16 | 4 | 1 | 1 | 4 | 2 | 0.5 |
| E104K, N276D | 16,000 | 1,000 | 250 | 4,000 | 2,000 | <32 | 2,000 | 1,000 | 500 | <16 | 4 | 2 | 2 | 4 | 2 | 1 |
| S268G, N276D | 16,000 | 2,000 | 500 | 4,000 | 2,000 | <32 | 4,000 | 2,000 | 500 | <16 | 1 | 1 | 1 | 1 | 1 | 0.12 |
| E104K, S268G, N276D | 16,000 | 1,000 | 500 | 4,000 | 2,000 | <32 | 4,000 | 1,000 | 500 | 64 | 8 | 2 | 2 | 8 | 4 | 2 |
| A42G, I47V, E104K, S268G, N276D | 32,000 | 4,000 | 1,000 | 8,000 | 4,000 | 2,000 | 8,000 | 2,000 | 1,000 | 1,000 | 16 | 4 | 4 | 8 | 8 | 8 |
a
Abbreviations: AMP, ampicillin; CLA, clavulanic acid; TZB, tazobactam; PIP, piperacillin; CAZ, ceftazidime. The numbers after the abbreviation's indicate concentrations (in micrograms per milliliter).
b
Wild-type TEM-1 β-lactamase.