<p>Annual distribution of MRSA and MSSA, 2013–2024.</p>

The MRSA share rose from 47.4% (2013) to 60.4% (2024), each later year being independently associated with MRSA (adjusted OR 1.09/year, 95% CI 1.06–1.12). MRSA was significantly more non-susceptible than MSSA to penicillin, ciprofloxacin, levofloxacin, erythromycin, clindamycin, gentamicin, trimethoprim–sulfamethoxazole, tetracycline, fusidic acid and rifampin (all FDR-adjusted p < 0.05), with the widest gap for fusidic acid (62.7% vs 25.0%); fusidic-acid and fluoroquinolone non-susceptibility also increased over time.

No vancomycin or daptomycin non-susceptibility was detected; teicoplanin non-susceptibility was low but significantly higher in MRSA (2.8% vs 1.5%), and low-level linezolid non-susceptibility (1.5% vs 1.3%) was not confirmatory-tested.</p> <p>Conclusions</p><p>In this single-center Aseer surveillance, MRSA became the majority of <i>S. aureus</i> during 2013–2024 and showed broad multidrug non-susceptibility, while vancomycin and daptomycin retained full in vitro activity.

These local findings support sustained laboratory-based surveillance, Aseer-tailored empirical and stewardship guidance, and confirmatory testing of the emerging low-level linezolid non-susceptibility signal.</p></div>