Biofilm formation is a key virulence factor in Staphylococcus aureus, contributing to bacterial persistence, antimicrobial resistance, and chronic infections. This study aimed to investigate the presence of biofilm-associated genes (fib, fnbA, fnbB, clfA, and clfB) in S. aureus isolates from dogs in Ilam, Iran. From December 2022 to September 2023, 250 swab samples were collected from the nasal, oral, and rectal sites of dogs, yielding 81 S. aureus isolates confirmed by polymerase chain reaction (PCR) amplification of the nuc gene. The prevalence of biofilm-associated genes varied, with clfA, clfB, and fnbA detected in 98.8% of isolates, fib in 63.0%, and fnbB in 16.0%. Notably, fnbA, clfA, and clfB were present in all rectal isolates, while fnbB was absent in this group. The findings highlight the widespread presence of biofilm-related genes in S. aureus from dogs, suggesting their potential role in colonization and zoonotic transmission. The high prevalence of adhesion-associated genes underscores the need for monitoring biofilm-forming S. aureus in companion animals to mitigate antimicrobial resistance and public health risks.
