TABLE 1.

MICs of β-lactams for the P. stuartii BI clinical isolate, E. coli DH10B harboring natural plasmid pNat-BI and recombinant plasmid pRec-BI, and E. coli DH10B reference strain

β-LactamaMIC (μg/ml) forb:
P. stuartii BIE. coli DH10B (pNat-BI)E. coli DH10B (pRec-BI)E. coli DH10B
Ticarcillin>512>512>5124
Ticarcillin-CLA8256644
Piperacillin512>512>5122
Piperacillin-TZB4842
Cefoxitin1444
Cefotaxime6432512<0.06
Cefotaxime-CLA0.5<0.060.12<0.06
Ceftazidime>512>512>5120.5
Ceftazidime-CLA0.50.2540.25
Cefuroxime128512>5124
Cefepime3216>512<0.06
Aztreonam128512>5120.12
Imipenem10.120.120.12
  • a CLA, clavulanic acid at a fixed concentration of 2 μg/ml; TZB, tazobactam at a fixed concentration of 4 μg/ml.

  • b The natural plasmid pNat-BI and the recombinant plasmid pRec-BI contained blaVEB-1b.