Table 2.

Synergistic in vitro activity of MC-207,110 combined with levofloxacin against the wild-type strain of P. aeruginosaand the strains overexpressing known efflux pumps

StrainGenotypeMC-207,110 MIC (μg/ml)Levofloxacin MIC (μg/ml) in the presence of MC-207,110 at concn (μg/ml) of:EmaxaEC50bFICindexc
00.6251.252.55102040
PAM1020Wild type>5120.1250.1250.1250.1250.030.0150.0080.0081650.140
PAM1032 nalB >512222110.1250.030.0364100.082
PAM1033 nfxB >51222220.50.1250.060.0364100.082
PAM1034 nfxC >512444410.250.060.0664100.082
PAM2391pMexXY>5120.250.250.250.250.030.0080.0080.0083250.052
PAM1626ΔmexAB-oprM ΔmexCD-oprJ ΔmexEF-oprN 640.0150.0150.0150.0150.0150.0150.0080.0082 NDd 1.156
  • a Emax, ratio between the MIC without EPI and the MIC in the presence of a maximal potentiating concentration of EPI.

  • b EC50, concentration of EPI at which a half potentiating effect is achieved.

  • c To calculate the FIC index for the wild type and the pump overexpressing strains, 513 μg/ml was used as the MIC of MC-207,110.

  • d ND, not determined.