Isolation and Molecular Detection of Mec-A Gene in Methicillin Resistant Staphylococcus aureus Colonizing Anterior Nares of School Children in Jos South, Nigeria

Aims: This study investigates and reports the carriage of MRSA in students of some Secondary Schools in Jos South Local Government.

Study Design: Cross-sectional study.

Place and Duration of Study: Molecular biology laboratory, Department of Microbiology, National Veterinary Research Institute, Vom, between February 2016 and March 2017.

Methodology: Staphylococcus aureus was isolated from the samples using standard cultural and microbiological methods. Antibiotic susceptibility testing was determined as described by the Clinical and Laboratory Standards Institute (CLSI). The detection of MRSA isolates was observed phenotypically using oxacillin and cefoxitin disc diffusion tests. In addition, molecular detection of MRSA mecA gene production was carried out using Polymerase Chain Reaction (PCR) method. Results: All samples isolated (100%) had Staphylococcus sp. with 114 (29.6%) isolates being S. aureus. Antibiotic resistance in the isolates in decreasing order was as follows: ceftazidime (48.2%), augmentin (37.8%), cefuroxime (35.0%), ceftriaxone (23.7%), ampicillin-sulbactam (21.9%), penicillin G (14.9%), ofloxacin (12.2%), gentamycin (11.4%), erythromycin (8.8%), vancomycin (0.0%). Eighteen of the 114 coagulase-positive S. aureus isolated (15.8%) were found to be MRSA using the oxacillin disc diffusion test, and thirteen of the MRSA detected (11.4%) identified using cefoxitin disc diffusion test to be also MRSA. The presence of methicillin-resistant gene (mec A) was confirmed in four (4) of the 18 MRSA isolates using the PCR technique.

Conclusion: The S. aureus isolates were less resistant to ampicillin-sulbactam, erythromycin, gentamycin, ofloxacin, and ceftriaxone, with vancomycin showing no resistance. In addition, mec A gene was detected in confirmed MRSA isolates.