Abstract

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Against the background of high level antimicrobial resistance observed in isolates of Staphylococcus aureus, this study was conducted to determine the prevalence of multidrug resistant (MDR) efflux pumps among clinical isolates from University of Benin Teaching Hospital, Benin city. A total of 198 clinical isolates of Staphylococcus aureus obtained from various clinical specimens were used for the study. Disc susceptibility test, detection of MDR efflux pump among representative multidrug Staphylococcus aureus isolates as well as curing experiments on the positive efflux pump isolates were performed using standard techniques. The most active antibacterial agent was imipenem with a susceptibility profile of 32.32%. A total of 64(32.32%) of the 198 isolates of Staphylococcus aureus were MDR. Forty-seven (47) isolates of Staphylococcus aureus (23.74%) were recovered from urine samples. Compared to isolates from other specimens, the prevalence of MDR isolates was significantly higher (63.83%) in the urine specimens (P˂ 0.0001). The prevalence of MDR efflux pump was 9.09% (18/198) with a significant prevalence among isolates from urine (P=0.0032). All 18 Staphylococcus aureus isolates harbored resistant plasmids to the drugs that were used as substrates for efflux as well as to other drugs. Curing experiment revealed the loss of antibacterial resistance in some of the isolates after exposure to rifampicin. In conclusion, the isolates of Staphylococcus aureus used for this study were multidrug resistant with few plasmid-mediated; consequently had a multiple antibiotic resistant index (MARI) ≥ 0.2. Prudent use of antimicrobial agents is advocated to stem the tide of high bacterial resistance

Keywords: clinical isolates, efflux pump, multidrug resistant, Staphylococcus aureus