Table 1.

Antibiotic susceptibilities of G1, G48, and G49 compared with efflux mutants

Class and compoundMIC (μg/ml) for:
G1G48G49Control nalB mutant (K766)aControl nfxB mutant (G385)aControl nfxC mutant (KG4001)b
β-Lactams
 Aztreonam4481644
 Carbenicillin161664641616
 Cefotaxime0.250.25440.250.25
 Cefoperazone22323222
 Cefpirome228882
 Ceftazidime118811
 Cephalothin44323244
 Imipenem0.50.50.50.50.54
 Meropenem0.50.5220.50.5
Quinolones
 Ciprofloxacin0.50.54242
 Clinafloxacin0.250.2521NDcND
 Enoxacin0.50.54442
 Fleroxacin443216168
 Gatifloxacin1184NDND
 Grepafloxacin1144NDND
 Levofloxacin1144NDND
 Moxifloxacin1144NDND
 Nalidixic acid128128>256>256>256>256
 Norfloxacin0.250.258422
 Pefloxacin0.50.54442
 Trovafloxacin1184NDND
Other agents
 Chloramphenicol44646464128
 Erythromycin32323232>25632
 Gentamicin0.50.50.50.50.250.5
 Sulfamethoxazole323264643232
 Tetracycline161664646416
 Trimethoprim64641281286464
  • a Strain kindly donated by K. Poole.

  • b Strain kindly donated by N. Gotoh.

  • c ND, not determined.