TABLE 1.

MICs of various antimicrobial agents for E. coli (KAM32/pUC18 and KAM32/pVBS1) and A. baumannii (AC0037, AC0037ΔabeS, and AC0037ΔabeSΩabeS) strains used in this study

CompoundMIC (μg/ml) for E. coli straind:Fold changeaMIC (μg/ml) for A. baumannii strain:Fold changecMIC (μg/ml) for A. baumannii AC0037ΔabeSΩabeS
pUC18/KAM32pVBS1/KAM32AC0037AC0037ΔabeSb
Amikacin1 (0.15)2 (0.15)22562561256
Chloramphenicol0.20.21256644128
Ciprofloxacin0.002 (0.0005)0.004 (0.0005)2120403>60
Erythromycin4 (<0.05)24 (0.25)6648832
Nalidixic acid1112561282256
Norfloxacin0.06 (0.001)0.12 (0.001)25122562>128
Novobiocin4 (<0.5)20 (<0.5)512040384
Rifampin2212212
Tetracycline0.5126464164
Trimethoprim0.1250.226464164
Acridine orange16805200504125
Acriflavine216812816864
Benzalkonium chloride1 (0.25)6 (0.25)64812424
Chlorhexidine2423216232
DAPI0.52420.542
Deoxycholate125 (<0.25)3,125 (5)25>2,048128>16512
EtBr2841,0241288>512
Methyl viologen64 (<2.5)128 (<2.5)28004002800
Pyronin Y4824224
Rhodamine 1238324128642128
Sodium dodecyl sulfate50 (<5)800 (<5)16>25616>16128
Tetraphenylphosphonium chloride8 (0.25)16 (0.25)21,5003005>500
  • a Ratio of MIC for pVBS1 to MIC for pUC18.

  • b AC0037ΔabeS did not show any difference in susceptibility toward imipenem, meropenem, and ceftazidime.

  • c Ratio of MIC for AC0037 to MIC for AC0037ΔabeS.

  • d Values in parentheses are MICs in the presence of the efflux pump inhibitor CCCP at 25 μg/ml.