Diversidade genética de Staphylococcus xylosus causadores de infecções intramamárias em ovelhas da raça Lacaune

Abstract

Ovine mastitis, frequently associated with Staphylococcus spp., represents a sanitary and economic challenge, particularly in dairy production systems. This study investigated the molecular epidemiology of S. xylosus in ovine mastitis cases, focusing on antimicrobial resistance genes and genetic diversity. Twenty-four S. xylosus-positive samples were analyzed, identifying the blaZ gene (β-lactamase) in 16.7% of isolates and the mecC gene (methicillin resistance) in 8.3%. No samples tested positive for the mecA gene, suggesting alternative resistance mechanisms, such as active efflux. RAPD-PCR analysis revealed genetic diversity among isolates, with distinct subtypes indicating heterogeneous transmission routes. The detection of mecC reinforces the role of S. xylosus as a reservoir for emerging resistance genes, posing risks of horizontal transfer to human pathogens. These findings underscore the need for continuous pathogen monitoring and the adoption of management practices to reduce antimicrobial selective pressure. Additionally, the lack of direct correlation between resistance genotype and phenotype highlights the importance of integrated approaches combining genomics and phenotypic assays to guide targeted therapies and control policies in ovine farming.