A systematic review and meta-analysis finds that colonizing strains of Staphyloccus aureus have a higher prevalence of resistance and virulence factors in low- and middle-income countries (LMICs) than in high-income countries (HICs), researchers reported yesterday in the Journal of Infection.
S aureus is known to colonize the nose and throat and can lead to a range of infections, some of which can be life-threatening, especially when the infection is caused by methicillin-resistant S aureus (MRSA). While several studies have documented the prevalence of S aureus in HICs, the prevalence of human colonization by S aureus in LMICs is not well known.
To determine the pooled prevalence of S aureus colonization among healthy individuals in LMICs, a team led by researchers at the University of Sheffield reviewed 139 studies involving 59,732 participants in 40 countries. As secondary objective was to assess antimicrobial resistance and virulence among colonizing strains.
Global approach to surveillance needed
The pooled prevalence of S aureus at nose and/or throat was 26.4% (95% confidence interval [CI], 23.8% to 29.1%), with the highest prevalence found in South America (36.7%; 95% CI, 24.6% to 48.9%), followed by Africa (31.0%; 95% CI, 25.7% to 36.7%) and Asia (22.4%; 95% CI, 19.5% to 25.4%). By comparison, previous studies of HICs have found a pooled prevalence rate of 21.6% in European countries and 28.6% in the United States.
The pooled prevalence of MRSA in colonizing S aureus strains was 15% (95% CI, 11.8% to 18.6%), with a higher prevalence observed in Africa compared with Asia and South America (22.5% vs 13.1% vs 5.4%, respectively). Panton-Valentine leukocidin (PVL) toxin genes, which are putatively associated with virulence and transmission, were present in 26.4% of 2,531 isolates. The study authors note that studies from Europe and the United States have reported MRSA prevalence of 0% to 2% among colonizing S aureus strains, while PVL has been detected in less than 1% of European studies.
"Given the significance of S. aureus as a human pathogen, our findings underscore the need for a global approach to surveillance to effectively deploy future infection prevention strategies," they wrote.