Detection of Multidrug Resistant Efflux Pumps in Clinical Isolates of E.coli in Tertiary Care Hospital

Fluoroquinolones are widely used in both community and hospital settings. E.coli exhibits multiple resistant mechanisms; recent studies showed that multidrug resistant (MDR) efflux mechanism is most common. The effects of MDR inhibitors of the RND efflux pumps, Reserpine 25 μg/ml and MC 207, 110 (Phe-Arg-beta-naphthylamide (PaβN), Sigma) 25 μg/ml, on the MIC of fluoroquinolones for clinical isolates of MDR E.coli were studied. The MIC of E.coli collected during the period of two years is tested with fluoroquinolones in the presence and in the absence of inhibitors by using the CLSI broth dilution method. In the presence of PaβN, only one strain of E.coli (1.8%) has shown greater than 8 fold reduction in MIC for ciprofloxacin. In the presence of reserpine change in MIC values was not observed in any of the clinical isolates of E. coli. These results indicate the need to identify overexpressing efflux pumps at diagnostic level.