Staphylococcus aureus in commercial laying hens from Pernambuco, Brazil: detection of efflux pumps and β-lactam resistance genes.

Antimicrobial resistance (AMR) in Staphylococcus aureus is a growing concern in poultry production, driven by the extensive use of antimicrobials for metaphylaxis, prophylaxis, and growth promotion. This study investigated genes linked to β-lactam resistance and multidrug efflux in S. aureus isolated from commercial laying hens and broilers in Pernambuco, Brazil. A total of 200 samples obtained from 100 birds (100 tracheal swabs and 100 cloacal swabs) were collected from 20 flocks. Bacterial DNA was extracted and subjected to PCR to confirm S. aureus and to detect blaZ, mecA, mecC, norA, norC, msrA, and tet38. S. aureus was identified in 5% (5/100) of the commercial birds tested, all from laying hens. Among these isolates, 20% (1/5) carried mecC and blaZ, 100% were positive for norA and norC, and 60% (3/5) for msrA. mecA and tet38 were not detected. These findings underscore the potential dissemination of S. aureus harboring resistance genes in poultry environments and highlight S. aureus as a reservoir of antimicrobial resistance in poultry production, with implications for animal and public health. Therefore, continuous surveillance and the prudent use of antimicrobials in animal production systems are necessary. Although efflux pump and mecC genes have been documented in Brazilian livestock, reports in poultry are scarce. These findings support the inclusion of these genetic determinants of resistance in national surveillance of antimicrobial resistance in poultry.