Characterization of biofilm formation and virulence factors of Staphylococcus aureus isolates from paediatric patients in Tehran, Iran

OBJECTIVE(S): Staphylococcus aureus can cause several infections. Its capability to form biofilm has been reported to be a vital property involved in the bacteria’s pathogenesis. Various genes contributing to biofilm formation have not yet been completely clarified. This study was designed to evaluate the factors influencing adherence and biofilm formation in S. aureus isolated from paediatric patients. MATERIALS AND METHODS: One hundred and ninety-seven S. aureus isolates were obtained from pediatric patients and confirmed with phenotypic and molecular examinations. Antimicrobial susceptibility testing and biofilm formation were evaluated using standard methods. The genes encoding adhesion and virulence factors were investigated by the PCR method. RESULTS: The most efficient antibiotics against S. aureus isolates were vancomycin and linezolid. Approximately, 54.2% of MSSA and 85.6% of MRSA isolates were biofilm producers according to the microtiter test. Our analysis indicated that MRSA isolates are better able to form biofilm compared with MSSA isolates. All isolates harbored clfA, fnbpA, icaA, icaB, icaC, and icaD, while clfB, fnbB, hlg, and pvl were detected in 99.5%, 42.1%, 97.5%, and 5.6% of isolates, respectively. In addition, a significant difference was found in fnhB gene and biofilm formation. CONCLUSION: Our findings showed a significant correlation between mecA and pvl genes and MRSA and biofilm formation in S. aureus isolates. Additionally, this study indicated the significant role of the fnhB gene as a major marker for S. aureus biofilm formation. Therefore, further experiments are warranted to exactly elucidate the function of the fnhB gene in the formation of biofilm.