Table 1.
MICs in mg/l of Variants Leading to SHV-129 with a Variety of β-Lactams and Inhibitors.
| AMP | THIN | CAZ | TAX | FEP | AZT | AMP-CLAVa | AMP-SULa | AMP-TAZOa | |
|---|---|---|---|---|---|---|---|---|---|
| Escherichia coli DH10B empty | 0.5 | 4–8 | <0.06 | <0.06 | <0.06 | <0.06 | 0.12 | 0.12 | 0.12 |
| SHV-1 | >16,384 | 256 | 4 | 0.12 | 1 | 0.12 | 8 | 512 | 64 |
| SHV-2 (G238S) | 4,096 | >512 | 16 | 16–32 | 4 | 1 | 0.5 | 16 | 8 |
| E240K | >16,384 | 128 | 16 | 0.12 | 0.5 | 0.12–0.25 | 4 | 256 | 64 |
| SHV-5 (G238S-E240K) | 1,024 | >512 | >32 | 32 | 4 | 32 | 0.5 | 16 | 8 |
| R275L | >16,384 | 256 | 4 | 0.12 | 0.12 | 0.12 | 2 | 128 | 16 |
| N276D | 16,384 | 32 | 4 | 0.12 | 1 | <0.06 | 16 | 256 | 64 |
| R275L-N276D | 8,192 | 32 | 4 | <0.06 | 1 | <0.06 | 4 | 128 | 32 |
| G238S-E240K-R275L | 2,048–4,096 | >512 | >32 | 16–32 | 8 | >32 | 0.25 | 8 | 8 |
| G238S-E240K-N276D | 2,048–4,096 | >512 | >32 | 16 | 8 | >32 | 0.5 | 8 | 8 |
| SHV-129 (G238S-E240K-R275L-N276D) | 2,048–4,096 | 512 | >32 | 4 | 16 | 32 | 0.5 | 8 | 8 |
| T182M | 8,192–16,384 | 32 | 0.12 | <0.06 | 0.12 | 0.12 | 0.5 | ND | ND |
Note.—AMP = ampicillin; THIN = cephalothin; CAZ = ceftazidime; FEP = cefepime; AZT = aztreonam; CLAV = clavulanic acid; SUL = sulbactam; TAZO = tazobactam; ND = not determined.
aInhibitor held constant at 4 mg/l and ampicillin concentration increased in doubling dilutions.