Nasal Colonization as a Risk Factor for Staphylococcal Infection: a Systematic Review and Meta-Analysis

Staphylococcus aureus (S. aureus) is a gram-positive bacterium found in clinical and community settings across the world. It is a major cause of both nosocomial and community-acquired staphylococcal infections. Nasal carriage rates of S. aureus and Methicillin resistant Staphylococcus aureus (MRSA) among hospital and non hospital centres have been reported in several Nigerian studies. Nevertheless, most of these studies presented local data, and no systematic study has been performed. Only 41 studies were included in this meta-analysis out of which only 24 studies reported MRSA colonization rates. The Meta-analysis of included studies reveals the pooled random effects estimate of nasal carriage of S. aureus and MRSA in Nigeria to be 41.5% (95% CI: 36.3-46.9) and 36.4% (95% CI: 27.7- 46.1), respectively. The high level of heterogeneity (S. aureus, 94% and MRSA, 92%) found in this study cannot be explained by chance, but by differences in study populations, methodology and geographical regions. Although not all infections* are causally related to persistent S. aureus and MRSA carriages, there is sufficient data to show that colonization by MRSA may act as a reservoir that can subsequently develop into an infection, once immunity wanes or immune defenses are breached. Therefore, proper screening and decolonization strategies should be nationally employed.