A four-year surveillance of β-lactam antibiotic resistance and MRSA in a tertiary hospital in Al-Kharj, Saudi Arabia.

BACKGROUND/OBJECTIVES: Methicillin-resistant Staphylococcus aureus (MRSA) is a major global pathogen and a critical public health concern. Understanding its epidemiology is essential for guiding effective treatment and infection control measures. This study aimed to describe temporal and specimen-specific resistance trends of S. aureus in Al-Kharj, Saudi Arabia, over a four-year period. METHODS: A retrospective analysis was conducted on 348 S. aureus isolates collected between 2021 and 2024 from a tertiary care hospital in Al-Kharj. Resistance patterns were assessed across blood, wound/infection, abscess, and respiratory samples, with a focus on four β-lactam antibiotics: penicillin, ampicillin, cefoxitin, and oxacillin. Statistical analyses were performed to evaluate temporal trends. RESULTS: Resistance to penicillin and ampicillin remained high throughout the study period, with penicillin resistance increasing significantly (p = 0.013) and ampicillin resistance rising gradually (p = 0.102). Cefoxitin and oxacillin resistance also increased, but these changes did not reach statistical significance (p = 0.243 and p = 0.065, respectively). Specimen-specific resistance was highest in respiratory samples (penicillin 100.0%, ampicillin 100.0%, cefoxitin 53.3%, oxacillin 45.2%) and abscess samples (penicillin 98.4%, ampicillin 98.5%, cefoxitin 67.3%, oxacillin 61.3%), while blood isolates showed lower resistance (penicillin 92.3%, ampicillin 96.0%, cefoxitin 47.7%, oxacillin 40.0%). MRSA analysis included 226 isolates with methicillin-susceptibility data. Of these, 114 isolates (50.4%) were MRSA, and 112 isolates (49.6%) were MSSA. MRSA proportions increased from 33.3% in 2021 to 53.6% in 2024; however, this trend did not reach statistical significance (Chi-square test for trend: χ² = 1.36, p = 0.243). CONCLUSIONS: To our knowledge, this is among the first four-year surveillance studies on S. aureus resistance in Al-Kharj. The findings highlight rising resistance, specimen-specific variability, and a gradual rise in MRSA prevalence. These results emphasize the need for ongoing surveillance and targeted antimicrobial stewardship to support national AMR strategies in Saudi Arabia.