Detection of efflux pump activity among clinical isolates of Staphylococcus and Micrococcus species

Purpose: To detect efflux pump activity (EPA) and screening a suspected efflux pump inhibitor (EPI) [1(3-(trifluoromethyl) benzyl]-piperazine (TFMBP)], which could help in reducing multi-drug resistance (MDR). Methods: Eighteen isolates, viz, 14 S. aureus, 2 S. lentus, 1 S. xylosus and 1 Micrococcus species from various hospital infections of admitted patients were screened for antibiotics susceptibility to 11 classes of antibiotics including oxacillin and beta-lactamase production. Efflux pump activity (EPA) was determined by minimum inhibitory concentration (MIC) technique in the presence and absence of TFMBP, the isolates were also screened for MDR genes. Results: All the isolates were resistant to ampicillin (10 mu g) and penicillin (10 mu g), but sensitive to bacitracin (10 mu g). Majority of the isolates were MDR 12/18 (66.7 %), 10 (55.6 %) were inducible beta-lactamase producers and 3 (16.7 %) were intrinsic beta-lactamase producers. Seven (38.9 %) were resistant to oxacillin and also produced carbapenemase enzyme. Eight (66.7 %) of the 12 MDR isolates gave evidence of EPA with TFMBP. However, no MDR genes were detected. Conclusion: Staphylococcus and Micrococcus species exhibit EPA in antibiotic resistance while a suitable EPI such as TFMBP when combined with specific antibiotics could help combat this menace.