TABLE 1.

MICs of β-lactams for E. aerogenes LOR and CF23.04 isolates and for recombinant E. coli DH10B(pBK-TEM-121), DH10B(pBK-TEM-24), and DH10B

β-LactamaMIC (μg/ml) for the following isolateb:
E. aerogenes LORE. coli DH10B(pBK-TEM-121)E. aerogenes CF24.03E. coli DH10B(pBK-TEM-24)E. coli DH10B
Amoxicillin>512>512>512>5122
Amoxicillin-CLA163251242
Ticarcillin>512>512>5125121
Ticarcillin-CLA128256128321
Piperacillin32641281281
Piperacillin-TZB481681
Cephalothin816>512>5124
Cefoxitin4212822
Cefuroxime88>5122560.5
Ceftriaxone<0.06<0.06328<0.06
Cefotaxime<0.06<0.06328<0.06
Ceftazidime128256512256<0.06
Aztreonam8165122560.06
Cefepime24440.06
Cefpirome24440.06
Imipenem0.060.060.060.060.06
  • a CLA, clavulanic acid at 2 μg/ml; TZB, tazobactam at 4 μg/ml.

  • b E. aerogenes isolate LOR produced β-lactamase TEM-121, whereas E. aerogenes CF24.03 produced TEM-24 and AmpC-type β-lactamases. Recombinant E. coli DH10B(pBK-TEM-121) and E. coli DH10B(pBK-TEM-24) produced β-lactamases TEM-121 and TEM-24, respectively.