Biofilm-associated genes and their role in antibiotic resistance among clinical Staphylococcus aureus isolates

INTRODUCTION: Staphylococcus aureus is a significant pathogen known for its ability to form biofilms, which enhances survival under adverse conditions. This study investigated the molecular mechanisms underlying biofilm formation in clinical S. aureus isolates, focusing on key biofilm-associated genes and their correlation with antibiotic resistance (ABR). METHODOLOGY: A total of 40 clinical S. aureus isolates were collected from Medical City Teaching Hospital, Baghdad. Biofilm production was assessed using the microtiter plate assay. Biofilm-related genes (icaB, icaC, crtM, crtN) were examined by polymerase chain reaction (PCR). Antimicrobial susceptibility was evaluated using the Kirby-Bauer disk diffusion method, and genes was correlated with resistance profiles. RESULTS: A significant variation in biofilm production was observed, with 80% of isolates classified as non-biofilm formers, 12.5% as weak, 5% as moderate, and 2.5% as strong biofilm producers. Genetic testing revealed that all investigated isolates had a high percentage of icaB and icaC, with 95 % possessing crtM. A significant prevalence of mecA (97.5 %) was observed; however, an increased prevalence of mecA did not correlate significantly with enhanced biofilm formation. CONCLUSIONS: This is the first report from Baghdad demonstrating the prevalence of these biofilm-associated genes and their link to ABR, offering potential targets for future therapeutic interventions. These results highlight the importance of biofilm-associated genes in the persistence and reinfection potential of S. aureus within clinical settings. Additionally, the common occurrence of icaB with icaC suggests that both genes could serve as new targets for developing treatments aimed at preventing biofilm formation and enhancing therapy effectiveness.