Assessment of biofilm formation, antibiotic resistance patterns, and the prevalence of adhesion-related genes in clinical Staphylococcus aureus isolates.

BACKGROUND: This study aimed to evaluate the biofilm formation abilities of clinical Staphylococcus aureus strains, assess their antibiotic susceptibility patterns, and identify the prevalence of adhesion-associated genes. METHODOLOGY: In this study, a total of 60 S. aureus strains were collected from urine, pus, wounds, blood, body fluid, and sputum in health centers affiliated with Abadan University of Medical Sciences, Iran. Strains were identified via microbiological methods and polymerase chain reaction (PCR) to target the nuc gene. Antibiotic susceptibility testing (AST) was conducted via the disc diffusion method. Methicillin-resistant S. aureus (MRSA) strains were identified by cefoxitin disc diffusion and PCR targeting the mecA gene. Biofilm formation was assessed via a microtiter plate assay, and the prevalence of adhesion-encoding genes was evaluated via PCR. The data were analyzed in Excel and SPSS via statistical methods, with P-values <0.05 considered significant. RESULTS: Using AST, daptomycin and linezolid were the most effective antibiotics (100 % susceptibility rate). According to the results of the cefoxitin disc test, 48.3 % (n = 29/60) of the strains were MRSA. All the MRSA strains harbored the mecA gene. In total, 32 % of the strains were biofilm producers. Moreover, 56.2 %, 28.1 %, and 15.6 % of the strains produced weak, moderate, and strong biofilms, respectively. There were no significant differences between the MRSA and MSSA strains in terms of the association of biofilm formation with antibiotic resistance except for erythromycin (P-value = 0.0087), gentamicin (P-value = 0.0009), and penicillin (P-value = 0.0009). The most prevalent biofilm-encoding genes were icaA (76.7 %), followed by icaD (70 %), clfA (65.0 %), and fnbA (53.3 %). CONCLUSION: This study identified MRSA strains with biofilm-forming abilities that possess adhesion-associated genes. The most prevalent biofilm-encoding gene was icaA. To prevent further spread of these strains, regional preventive measures are needed.