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 β-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 μg) and penicillin (10 μg), but sensitive to bacitracin (10 μg). Majority of the isolates were MDR 12/18 (66.7 %), 10 (55.6 %) were inducible β- lactamase producers and 3 (16.7 %) were intrinsic β-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. Keywords : [1-(3-(Trifluoromethyl)benzyl]-piperazine, Efflux pump activity, Oxacillin resistant S. aureus , Multidrug resistant, Carbapenemase