Table 1.

MICs of β-lactams for the P. aeruginosa ED-1 clinical isolate, its transconjugant P. aeruginosaPU21(pGIR-1), reference strain P. aeruginosa PU21,E. coli DH10B(pDG-1), and reference strain E. coli DH10B

β-LactamaMIC (μg/ml) for:
P. aeruginosa ED-1P. aeruginosa PU21 (pGIR-1)bP. aeruginosaPU21E. coli DH10B (pDG-1)bE. coli DH10B
Amoxicillin>512>51232162
Ticarcillin6412816322
Ticarcillin plus CLA6412816321
Piperacillin8162321
Piperacillin plus TZB8161161
Cephalothin>128>128>12884
Cefsulodin256642322
Cefuroxime>128>128>12844
Ceftazidime2565120.251280.06
Ceftazidime plus CLA128640.25640.06
Cefotaxime1616240.12
Cefepime32160.060.5<0.06
Moxalactam128256810.25
Aztreonam32320.580.12
Imipenem20.250.120.060.06
  • a CLA, clavulanic acid at a fixed concentration of 2 μg/ml; TZB, tazobactam at a fixed concentration of 4 μg/ml.

  • b P. aeruginosa PU21 harboring natural plasmid pGIR-1 and E. coli DH10B harboring recombinant plasmid pDG-1 produced the β-lactamase OXA-28.