TABLE 3

Molecular sizes and lipophilicities of antimicrobial agents and their relation with the effect of acrAB deletion on MICs in E. coli K-12a

AgentMolecular weightLipophilicity (XlogP3)cMIC (μg/ml) for strain
acrAB+ΔacrAB
Lipophilic and/or large agents
    Clotrimazole3455.0>3216
    Cloxacillinb 4362.42562
    Erythromycin7342.7501.56
    Fusidic acid5175.54003.125
    Methotrexate454−1.8>64080
    Novobiocin6133.31001.56
    Puromycin4720.01001.56
    Rifampin8234.052.5
    SDS2884.7>12,800100
Small and hydrophilic agents
    Ampicillin349−1.112.53.12
    Cephalothinb 396−0.444
    Cefoxitinb 4270.041
    Ceftazidimeb 5470.40.120.12
    Imipenemb 317−0.70.120.12
    Nalidixic acid2321.43.131.56
    Norfloxacin319−1.00.0040.004
    Ciprofloxacin331−1.10.010.0025
    Chloramphenicol3231.16.250.78
    Tetracycline444−2.01.250.156
  • a The MIC data are mostly from reference 27.

  • b MIC data are from reference 188.

  • c The values of logP (the logarithm of the partition coefficient between n-octanol and water) are from PubChem (http://pubchem.ncbi.nlm.nih.gov/) based on the calculation by the XlogP3 method.