Low Panton–Valentine leukocidin prevalence in circulating community MRSA: a genomic surveillance study in Qatar

BACKGROUND: Staphylococcus aureus (S. aureus), particularly methicillin-resistant S. aureus (MRSA), is a major human pathogen causing severe infections. While well studied in hospitals, limited data exist on the transmission and antimicrobial resistance (AMR) profiles of community-associated MRSA (CA-MRSA) in the Gulf region. This study investigated the AMR patterns of CA-MRSA. METHODS: Nasal and axillary swabs from 576 asymptomatic residents of Qatar without a history of hospitalization, surgery, dialysis, or indwelling medical devices in the preceding 12 months, and those who have not used antibiotics within the previous 3 months were analyzed. S. aureus was isolated on mannitol salt agar, confirmed by VITEK® 2 Compact, and methicillin resistance was determined by cefoxitin disc diffusion. AMR profiling followed CLSI guidelines. PCR and whole-genome sequencing using the GridION platform were performed for molecular confirmation and genomic characterization, including gene annotation and phylogenetic analysis. All sequences were deposited in NCBI. RESULTS: Of 60 confirmed S. aureus isolates (10.4% prevalence), 35% (n = 21) were MRSA, yielding an overall MRSA carriage prevalence of 3.6% (21/576). Most MRSA isolates came from young asymptomatic individuals aged 18 to 45 (80%, 17/21) and from men (58%, 12/21). Among the 21 MRSA isolates identified in this cohort, resistance rates were 29% for erythromycin and ciprofloxacin, 24% for tetracycline, 14% for gentamicin, and 10% for sulfonamides. A total of 71% of the isolates exhibited multidrug resistance. All MRSA isolates carried the methicillin resistance gene (mecA), while 4.7% harbored the Panton-Valentine leukocidin (PVL) gene. Phylogenetic analysis revealed four distinct clusters, indicating a polyclonal community rather than a single spreading strain. CONCLUSIONS: The prevalence of multidrug-resistant MRSA with key virulence factors may represent a continuing public health concern, underscoring the need for strengthened community surveillance, antimicrobial stewardship, and infection control to monitor and limit the spread of multiple circulating strains.