Table 1.

Susceptibilities of PAO1 and its β-lactamase- and/or efflux system-deficient mutants to various β-lactams

Group and antimicrobial agentMIC (μg/ml)a
PAO1KG2239KG2504KG2507
Group I
 Carbenicillin250.39250.10
 Piperacillin1.560.201.560.05
 Cefoperazone3.130.391.560.10
 Aztreonam3.130.101.560.05
 Cefsulodin0.780.200.780.20
Group II
 Amoxicillin3,2001,6006.250.10
 Cefmetazole1,6001,6001000.20
 Flomoxef6,4006,40012.50.20
 Panipenem3.133.130.200.10
 Imipenem0.780.780.200.20
Group III
 Cefpodoxime4004001000.20
 Cefuroxime8004004000.78
 Ceftriaxone6.2512.53.130.20
 Moxalactam6.253.136.250.39
 Meropenem0.390.200.200.012
 S-46610.200.390.100.025
  • a PAO1 produced AmpC and MexAB-OprM, KG2239 produced AmpC but was MexAB-OprM deficient, KG2504 was AmpC deficient but produced MexAB-OprM, and KG2507 was AmpC and MexAB-OprM deficient.