Prevalence and Antimicrobial Susceptibility of Methicillin Resistant Staphylococcus aureus and Coagulase-Negative Staphylococci Isolated from Apparently Healthy University Students in Ota, Nigeria

Abstract

In Nigeria, high prevalence of methicillin resistant Staphylococcus aureus (MRSA) in clinical samples and healthy individuals is increasingly being reported. However, very little is known regarding coagulase negative Staphylococci (CoNS) strains isolated from healthy individuals, especially, given their increasing recognition as agents of clinically significant infections and as reservoirs of antimicrobial resistance determinants. Therefore, this study was undertaken, to establish the prevalence of MRSA, and to characterize the antimicrobial susceptibility of CoNS strains from apparently healthy University student volunteers in Ota, Ogun State, Nigeria. A better characterization of CoNS strains in their commensal lifestyle could give us new insights on their pathogenic potential. A total of 100 (nose and neck swabs) samples were collected from healthy students and screened using standard microbiological techniques. Staphylococcus species isolated on the basis of growth on mannitol salt agar were further characterized based on biochemical tests and novobiocin resistance. Commercially prepared antibiotics discs were used to test the susceptibility of the Staphylococcus isolates obtained. Data generated were analyzed descriptively and expressed in percentages. A total of 39 Staphylococcus species were identified as S. aureus (17), S. saprophyticus (8), S. epidermidis (7), S. hemolyticus (5) and S. hominis (2). The S. aureus strains were highly resistant (>94%) to methicillin (oxacillin / cloxacillin) and several non-β-lactams including clindamycin (100%), co-trimoxazole (82.4%), and vancomycin (82.4%). The incidence of methicillin resistance among CoNS was 77.3% with moderate resistance to co-trimoxazole (63.6%), clindamycin (40.9%), gentamicin (36.36%) and vancomycin (31.8%). This study has demonstrated high prevalence of MRSA and MRCoNS isolates from apparently healthy University student volunteers in Ota, Nigeria, and underlines the need for periodic surveillance studies of this type, reassessment of policies on antibiotics use within and outside the University environments, development and enforcement of measures to prevent the spread of MRSA and MRCoNS infections in the community.

Keywords: Coagulase-Negative Staphylococcus species (CoNS), Community-associated methicillin resistant Staphylococcus aureus (CA-MRSA), Multi-drug resistance, Nigeria, Susceptibility