Intersecting realms of resistance: the epidemiology of Staphylococcus aureus carriage and multidrug resistance in primary healthcare settings in Recife, Brazil.

The rise of antimicrobial resistance (AMR) poses a critical threat to global health, with Methicillin-resistant Staphylococcus aureus (MRSA) being a significant concern in both human and veterinary medicine. This study aimed to investigate the prevalence and genetic characteristics of S. aureus isolates from primary care units in Recife, Brazil, encompassing human, animal, and environmental samples. A total of 258 isolates were collected, with 97 confirmed as S. aureus through PCR targeting the nuc gene. The isolates were subjected to phenotypic and genotypic analyses to determine their resistance profiles. The results revealed a high prevalence of resistance genes, including mecA (66.0%), mecC (1.0%), blaZ (87.6%), norA (95.9%), and norC (95.9%), indicating diverse resistance mechanisms. Notably, a mecC-positive S. aureus isolate was identified in a canine, marking the first report of this gene in a clinical isolate from a dog in Brazil. The phenotypic resistance assessment showed significant resistance to beta-lactam antibiotics, with 80.41% of isolates resistant to penicillin. Multidrug resistance (MDR) was observed in 12.4% of the isolates, with PFGE genotyping revealing two distinct clusters, suggesting potential clonal dissemination within the healthcare environment. These findings underscore the urgent need for robust infection control measures, continuous surveillance, and advanced diagnostic methods to manage and mitigate the spread of MDR S. aureus. The study highlights the importance of integrated approaches in both human and veterinary medicine to address the complex landscape of antimicrobial resistance.