Beta-lactamase production among different agr groups of Staphylococcus pseudintermedius isolates from broilers.

Staphylococcus pseudintermedius is an opportunistic inhabitant of skin and mucosal membranes in animal species. Its resistance to β-lactam antibiotics is usually measured by β-lactamase enzyme production. This study was aimed to identify S. pseudintermedius from broilers, determine the prevalence of blaZ gene, and evaluate the relationship between agr type and β-lactamase gene expression. Fifty swabs from nasal cavities of broilers were sampled. To identify S. pseudintermedius, the nuc gene was amplified by PCR. Antibiotic susceptibility testing was performed on the isolates by the Kirby Bauer technique, and the presence of blaZ gene was detected. Finally, the relative gene expression of blaZ was determined in each agr group. Results of gene amplification showed that 33 samples (66 %) contained nuc gene of which 21 samples horbored blaZ and were resistant to penicillin (%63). The Multiplex PCR was used to determine the agr type of blaZ positive isolates. Of the strains, 70 % were categorized in the agr I group, 21 % in the agr II group, 0 % in the agr III group, and 9 % in the agr IV group. Results of relative gene expression of blaZ with gyr B as a housekeeping gene showed that the change fold of the blaZ gene was significantly higher in the agr I group compared to the other groups (p ≤ 0.05). These data suggested that agr activity may influence the resistance of S. pseudointermedius to β-lactam antibiotics. In this study, S. pseudintermedius was isolated for the first time from the nasal cavities of broilers.