Abstract / Summary
Staphylococcus aureus , particularly methicillin-resistant S. aureus (MRSA), is a major cause of infection and antimicrobial resistance in resource-limited settings, and accurate detection depends on reliable species identification and methicillin-resistance screening. In many sub-Saharan African laboratories, S. aureus is identified using non-standardised phenotypic methods, and MRSA screening is not routinely performed. In this cross-sectional study, isolates phenotypically identified as S. aureus by six health facilities in the South West and Littoral Regions of Cameroon between May 2021 and July 2022 were re-identified using nuc gene PCR as the reference standard. MRSA was detected using mecA gene PCR, and antimicrobial susceptibility was determined for MRSA isolates by the Kirby-Bauer disc diffusion method according to CLSI guidelines. Of 188 isolates phenotypically identified as S. aureus , only 26 (13.8%; 95% CI 9.5–19.5%) were confirmed by nuc gene PCR, corresponding to an overall misidentification rate of 86.2%. Seven of the 26 confirmed isolates (26.9%) were MRSA, all of which were multidrug-resistant. No participating facility routinely screened for MRSA. These findings reveal substantial phenotypic misidentification of S. aureus and indicate that MRSA infections would go undetected under current routine practice, underscoring the urgent need for standardised, validated identification methods and routine MRSA screening.