Prevalence and associated risk factors of Staphylococcus aureus nasal colonization among a cohort of immunocompromised individuals in Lagos, Nigeria

Abstract

Background Immunocompromised individuals are highly vulnerable to Staphylococcus aureus (S. aureus) infections, leading to increased morbidity and mortality. This study aimed to assess the prevalence, virulence, and risk factors associated with S. aureus nasal carriage among immunocompromised individuals in Lagos, Nigeria. Methods A total of 350 participants were enrolled, including 150 HIV/AIDS cases, 50 HIV/TB co-infections, 100 diabetes cases, and 50 controls. Nasal swabs were collected and cultured on Mannitol salt agar for the isolation of Staphylococcus aureus. Presumptive isolates were confirmed using Gram staining, catalase, and coagulase tests. Antimicrobial susceptibility was determined using the Kirby-Bauer disk diffusion method in accordance with CLSI guidelines. Molecular detection of resistance and virulence genes was performed using PCR targeting the mecA gene (methicillin resistance) and pvl (Panton-Valentine leukocidin). A structured questionnaire capturing clinical history and hygiene practices was used to evaluate risk factors for S. aureus carriage. Results The overall prevalence of S. aureus was 14.6% (51/350), S. aureus was isolated in 28% (14/50) of controls, 16.7% (25/150) of HIV/AIDS patients, 14% (7/50) of HIV/TB cases and 5% (5/100) of diabetes cases. Susceptibility to erythromycin was 80.4%, gentamycin, ciprofloxacin and Sulfamethoxazole-Trimethoprim (64.7%) among all S. aureus isolated. Methicillin-resistant S. aureus (MRSA) was detected in 78.4% (40/51) of isolates, predominantly among HIV/AIDS patients (52.5%). pvl genes were identified in 11.8% (6/51) of isolates. S. aureus carriage was significantly associated with recent antibiotic use (p = 0.003) and contact with animals (p = 0.018). Conclusion This study demonstrates a high prevalence of S. aureus among controls compared to immunocompromised individuals. These results highlight the need for further studies to elucidate the relationship between host factors and S. aureus colonization. This could inform targeted strategies for infection prevention and control.