Table 1.
In vitro antibacterial activity of different β-lactam/β-lactamase inhibitor combinations against strains of Enterobacteriaceae species
| MIC in mg/L (fold decrease with NXL104) |
||||||
|---|---|---|---|---|---|---|
| Antimicrobial/β-lactamase inhibitora | K. pneumoniae VA8 (KPC-3)b | K. pneumoniae VAKP (KPC-2) | K. pneumoniae YC (KPC-2) | E. coli 2138(KPC-2, TEM-1) | E. cloacae 7506(KPC-2, TEM-1, KLUC-2) | E. cloacae MAC (KPC-3, TEM-1, OXA-9) |
| NXL104 | >128 | >128 | >128 | >128 | >128 | 128 |
| AMX | >2048 | >2048 | >2048 | >2048 | >2048 | >2048 |
| AMX + CLA | 32 | >2048 | >2048 | >2048 | >2048 | >2048 |
| AMX + NXL104 | 64 (64) | 128 (≥32) | 256 (≥16) | 128 (≥32) | 512 (≥8) | 256 (≥16) |
| PIP | 2048 | 2048 | >2048 | >2048 | >2048 | >2048 |
| PIP + TZB | 256 | 1024 | >2048 | >2048 | >2048 | >2048 |
| PIP + NXL104 | 4 (512) | 8 (256) | 8 (≥512) | 4 (≥1024) | 32 (≥128) | 16 (≥256) |
| CAZ | 512 | 512 | 1024 | 64 | 512 | 1024 |
| CAZ + TZB | 2 | 64 | 256 | 32 | 512 | 512 |
| CAZ + CLA | 0.25 | 16 | 128 | 32 | 512 | 512 |
| CAZ + NXL104 | 0.5 (1024) | 0.5 (1024) | 1 (1024) | 0.25 (256) | 8 (64) | 8 (128) |
| CRO | 128 | 256 | >2048 | >2048 | >2048 | >2048 |
| CRO + NXL104 | 0.06 (2048) | 0.06 (4096) | 0.25 (≥16 384) | 0.06 (≥65 536) | 1 (≥4096) | 0.5 (≥8192) |
| IPM | 1 | 16 | 32 | 16 | 128 | 64 |
| IPM + NXL104 | 0.5 (2) | 0.5 (32) | 0.25 (64) | 0.5 (32) | 0.5 (256) | 2 (32) |
CAZ, ceftazidime; PIP, piperacillin; CRO, ceftriaxone; AMX, amoxicillin; IPM, imipenem; CLA, clavulanate; TZB, tazobactam.
aInhibitors were added at fixed 4 mg/L concentration.
bEnzymes possessed by each strain are shown in parentheses.