Table 4.

Frequency of LVX-resistant mutants in strains with deletions of the efflux pump operons

StrainPump statusLVX MIC (μg/ml)Frequency of LVX-resistant mutantsa
PAM1020WTb 0.252 × 10−7–4 × 10−7
PAM1554ΔmexAB-oprM::Cm0.0152 × 10−7–4 × 10−7
PAM1409ΔmexCD-oprJ::Gm0.252 × 10−7–4 × 10−7
PAM1623ΔmexEF-oprN::ΩHg0.252 × 10−7–4 × 10−7
PAM1625ΔmexAB-oprM::Cm ΔmexEF-oprN::ΩHg0.0152 × 10−7–10−7
PAM1624ΔmexCD-oprJ::Gm ΔmexEF-oprN::ΩHg0.25 2 × 10−6 
PAM1561ΔmexAB-oprM::Cm ΔmexCD-oprJ::Gm0.015 1 × 10−9 
PAM1626ΔmexAB-oprM::Cm ΔmexCD-oprJ::Gm ΔmexEF-oprN::ΩHg0.015<1 × 10−11
  • a The frequency of resistance to LVX was determined by plating 100 μl of an overnight culture of the corresponding mutant strain onto LBA containing LVX (1 μg/ml). Frequencies were determined as ratios between the number of colonies that grew on LBA plates containing LVX (expressed as numbers of CFU per milliliter to the number of colonies appearing on drug-free LBA plates after overnight growth.

  • b WT, wild type.