TABLE 1.

MICs of β-lactams for the E. coli 271 clinical isolate, E. coli TOP10 harboring recombinant plasmid p271A expressing NDM-1, and the E. coli TOP10 reference strain

β-Lactam(s)aMIC (μg/ml) for:
E. coli 271E. coli TOP10(p271A)E. coli TOP10
Amoxicillin>512>5124
Amoxicillin + CLA2562564
Ticarcillin>512>5124
Ticarcillin + CLA5125124
Piperacillin>5125121
Piperacillin + TZB5125121
Cefoxitin5122564
Ceftazidime2561280.06
Cefotaxime5122560.12
Cefepime64160.06
Aztreonam640.250.12
Imipenem640.06
Meropenem1630.06
Ertapenem3230.06
  • a CLA, clavulanic acid at a fixed concentration of 4 μg/ml; TZB, tazobactam at a fixed concentration of 4 μg/ml.