Veterinary Research Forum

Abstract The accessory gene regulator(agr) operon as a part of the quorum-sensing (QS) system, is responsible for the regulation of numerous virulence factors in Staphylococci. Furthermore, the ability of the opportunistic pathogen, Staphylococcus pseudintermedius to form biofilm is a significant contributor to chronic diseases. Our aim was evaluation of the association between different agr groups and the expression of icaD gene related to biofilm formation among S. pseudintermedius from nasal samples. Fifty nasal swabs were collected from broiler chickens; then phenotypic and molecular tests performed for isolation of S. pseudintermedius from samples and their agr genotype was also investigated. The biofilm production capacity of the isolates was determined using both microtiter plate assay and amplification of icaD gene. S. pseudintermedius was detected in 86.84% of samples. The assessment of agr typing results related that most of the strains (69.70%) were classified in agr group ɪ. The relative frequency of biofilm producing S. pseudintermedius isolates was 75.76% and all of them harbored icaD gene. The expression level of icaD determinant was significantly higher among isolates in agr group ɪ than other agr groups. The results suggest that broiler chickens may act as a reservoir for transmission of S. pseudintermedius to humans which should be considered a potential zoonotic bacterium able to produce different virulence factors like biofilm.

Abstract 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 nasal, oral, and rectal sites of dogs, yielding 81 S. aureus isolates confirmed by PCR amplification of the nuc gene. The prevalence of biofilm-associated genes varied, with clfA, clfB, and fnbA detected in 98.80% of isolates, fib in 63.00%, and fnbB in 16.00%. Notably, fnbA, clfA, and clfB were present in all rectal isolates, while fnbB was absent in this group. The findings highlighted 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 underscored the need for monitoring biofilm-forming S. aureus in companion animals to mitigate antimicrobial resistance and public health risks.

Abstract Streptococcus agalactiae is a major contagious pathogen causing bovine sub-clinical mastitis. The present investigation was carried out to determine some phenotypic characteristics of the S. agalactiae strains isolated from bovine mastitis cases in dairy cows of Shahrekord in the west-center of Iran. One hundred eighty California mastitis test (CMT) positive milk samples were bacteriologically studied. A total of 31 (17.2%) S. agalactiae isolated. Twenty eight (90.3%) of the isolates were biofilm producers. This finding may indicate the high potential of pathogenicity in isolated strains. Sixteen (51.6%) isolates were α hemolysin producers. Only 19.3%, 22.5% and 29.0% of the isolates were sensitive to streptomycin, flumequine and kanamycin, respectively. None of these three agents is recommended for treatment of mastitis cases.