مشخصات پژوهش

Abstract Background & Objectives: Staphylococcus aureus infections, particularly methicillin-resistant strains (MRSA), are common in healthcare settings and are associated with prolonged hospitalization and increased mortality. This study aimed to evaluate the prevalence, antimicrobial resistance, biofilm formation, and risk factors associated with mortality among methicillin-sensitive (MSSA) and methicillin-resistant (MRSA) isolates in hospitals in Tehran. Materials & methods: In a descriptive, cross-sectional study, 160 clinical isolates from ICU patients at two hospitals were collected. Identification of S. aureus was performed using biochemical and molecular methods targeting the nucA and mecA genes. Antimicrobial susceptibility was assessed by the Kirby-Bauer disk diffusion and minimum inhibitory concentration methods. Biofilm formation was evaluated using the microtiter plate assay. Demographic and clinical data were recorded for statistical analysis. Results: S. aureus was detected in 30 patients (18.75%), of which 46.7% were MRSA. Sixty percent of the patients were male with a mean age of 60.5 years. Comorbidities were present in 53.3% of cases, and overall mortality was 50%. ICU length of stay was significantly associated with mortality. Vancomycin use was higher in MRSA cases. High resistance rates were observed to penicillin (100%), azithromycin (70%), ofloxacin (63.3%), and ciprofloxacin (56.7%). MRSA isolates exhibited stronger biofilm formation, and biofilm-producing MRSA strains had significantly higher resistance to azithromycin, ciprofloxacin, and ofloxacin. Conclusion: The high prevalence of antibiotic-resistant MRSA isolates, their enhanced biofilm-forming capacity, and the significant association between prolonged ICU stay and mortality highlight the urgent need for rigorous monitoring and the development of effective therapeutic strategies to improve patient outcomes.