Table 1.

MICs of β-lactams for reference strain K. cryocrescens 79.54, E. coli DH10B(pKC7954), and reference strain E. coli DH10B

β-Lactam(s)bMIC (μg/ml)a
K. cryocrescens79.54E. coli DH10B (pKC7954)E. coliDH10B
Amoxicillin64>5122
Amoxicillin + CLA<0.582
Ticarcillin128>5121
Ticarcillin + CLA181
Piperacillin<11281
Piperacillin + TZB<1<11
Cephalothin8>5122
Cefuroxime165122
Cefotaxime0.068<0.06
Cefotaxime + CLA<0.060.06<0.06
Cefotaxime + TZB<0.060.12<0.06
Ceftazidime<0.060.5<0.06
Ceftazidime + CLA<0.060.12<0.06
Ceftazidime + TZB<0.060.12<0.06
Ceftriaxone<0.06128<0.06
Cefepime<0.061<0.06
Cefepime + CLA<0.060.25<0.06
Cefepime + TZB<0.060.12<0.06
Cefpirome<0.064<0.06
Cefpirome + CLA<0.06<0.06<0.06
Cefpirome + TZB<0.06<0.06<0.06
Cefoxitin142
Moxalactam0.030.120.12
Aztreonam0.0620.06
Meropenem<0.03<0.06<0.06
Imipenem0.060.120.12
  • a K. cryocrescens 79.54 andE. coli DH10B(pKC7954) produced the KLUC-1 β-lactamase.

  • b CLA, clavulanic acid at a fixed concentration of 2 μg/ml; TZB, tazobactam at a fixed concentration of 4 μg/ml.