Molecular Epidemiology of Staphylococcus Aureus Causing Post-Orthopaedic Surgical Site Infections in Lagos State Teaching Hospitals

Staphylococcus aureus is the leading causative organism in post-orthopaedic surgical site infections and implant-related infections, with methicillin-resistant strains (MRSA) presenting escalating treatment challenges. This prospective microbiological and epidemiological study characterises the molecular epidemiology and antibiotic resistance patterns of S. aureus isolates from post-orthopaedic surgical site infections at Lagos University Teaching Hospital and Lagos State University Teaching Hospital, South West Nigeria, over a twelve-month period. Wound swabs from confirmed surgical site infections will be cultured, and S. aureus isolates identified by standard microbiological methods. Antibiotic sensitivity testing will be performed using the Kirby-Bauer disc diffusion method. MRSA isolates will be genotyped using polymerase chain reaction (PCR) for the mecA gene. Healthcare worker nasal carriage prevalence will be assessed as a secondary investigation. Descriptive statistics and chi-square analysis will compare resistance profiles across hospital and surgery type. The study hypothesises a high MRSA prevalence exceeding 30 percent among isolates, consistent with West African regional trends. Findings will be communicated to the hospitals' infection control units and contribute to evidence-based empirical antibiotic selection for orthopaedic surgical prophylaxis and treatment in South West Nigeria. Keywords: Staphylococcus aureus, MRSA, surgical site infections, orthopaedic surgery, molecular epidemiology.