Molecular characterization of selected nasal isolates of methicillin-resistant Staphylococcus aureus (MRSA) from healthy students of a tertiary institution

Abstract

Purpose: To investigate the incidence of methicillin-resistant Staphylococcus aureus (MRSA) and carry out molecular characterization in selected nasal isolates from healthy students in Abraka, Nigeria. Methods: Three hundred (300) samples were obtained from apparently healthy 150 female and 150 male students and were cultured in suitable media for identification. The MRSA were detected by means of oxacillin antibiotic sensitivity disk. Antibiotics susceptibility pattern of MRSA isolates was carried out in accordance with the guidelines of Clinical Laboratory Standard Institute. Tests were carried out to determine the presence of penicillin binding protein2a (PBP2a). Molecular characterization of twenty (20) MRSA representatives was done to establish the existence of the mecA genes among the isolates. Results: The incidence of MRSA colonization amongst apparently healthy students in the community was 68 (22.7 %). The sensitivity pattern was: amoxicillin, 40 (58.8 %); amoxicillin/clavulanate, 15 (22.1%); chloramphenicol, 15 (22.1 %); ciprofloxacin, 19 (27.9 %); co-trimoxazole, 9 (13.2 %); gentamicin, 9 (13.2 %); ofloxacin, 8 (11.1 %); and streptomycin, 30 (44.1 %). All the twenty (20) isolates subjected to molecular characterization possessed penicillin binding protein2a (PBP2a) while only one possessed the mecA gene. Conclusion: The MRSA is present among healthy individuals in Abraka, Delta State. It is also possible not to detect the existence of the mecA gene even when penicillin binding protein2a is present. Since most of the MRSA isolates are multi-drug resistant, there is a tendency for clinical antibiotic therapy failure in this area.