Occurrence of methicillin-resistant Staphylococcus aureus (MRSA) in 'coalho' cheese produced in Brazil

The experiments reported in this research communication analysed the presence of methicillin-resistant Staphylococcus aureus (MRSA) in 112 samples of 'coalho' cheese, from 56 dairy producing farms in 28 cities in all mesoregions of the State of Ceara, Brazil. To assess antimicrobial resistance we also examined the presence of genes encoding enterotoxins and toxic shock syndrome toxin, as well as the presence of the blaZ gene for beta-lactamases, and resistance to oxacillin. The research found 69 isolates of S. aureus, of which 13.04% had the mecA gene encoding the penicillin-binding protein, which confers resistance to methicillin, in cheese samples from 6 different cities. This included the state capital, Fortaleza, which had the largest prevalence (23.19%) of mecA positive isolates. It was also found that 55.07% of the isolates of S. aureus had the blaZ gene, and 7.25% demonstrated resistance to oxacillin in the plate disc diffusion tests. We did not show the presence of isolates carrying toxigenic genes. The findings suggest that strict supervision of production processes in the dairy industry is necessary in all production scale processes, thus preventing contamination and possible problems for consumers.