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Aims Staphylococcus aureus is one of the most common pathogens associated with mastitis in dairy herds worldwide. This study evaluated the profile of virulence and antimicrobial resistance genes of spa type t605 methicillin-susceptible Staphylococcus aureus isolated from subclinical bovine mastitis in São Paulo, Brazil. Methods and results Fifty-seven S. aureus strains were screened by conventional PCR for 49 virulence genes. The most prevalent virulence genes detected were icaD (94.7%), fib (93%), fnbA (82.5%), clfA (80.7%), bap (78.9%), clfB (73.7%), icaA (66.7%), see (64.9%), and sed (61.4%). The blaZ (94.7%), aac6’aph2’ (15.8%), and ant4 (12.3%) genes were the most common antimicrobial resistance genes; however, mecA and mecC genes were not found. All methicillin-susceptible S. aureus (MSSA) strains were characterised through spa and agr typing. The spa type t605 was found in all isolates. By agr typing, the most prevalent were type II (56.1%). Antimicrobial resistance was determined by the disk diffusion method, and 93% showed resistance to at least one antibiotic. Penicillin resistance was the most prevalent (87.7%), followed by tetracycline (12.3%), oxacillin (10.5%), and gentamicin (10.5%) resistance. Conclusion Our study confirmed the spa type t605 as endemic, carrying a wide variety of virulence factors and high-level penicillin resistance. The profile seems to be associated with the colonisation of MSSA and its persistence in subclinical mastitis.

Staphylococcus aureus is a foodborne associated pathogen, mainly in dairy products due to the enterotoxin production. This study analyzed the production of classical toxins in cheese by S. aureus, in different temperatures, atmospheres, and levels of contamination. Minas Frescal Cheese were classified according to their microbiota. The cheese samples were classified as low or high level of contamination according to the concentration of that bacteria. An aliquot of 10 5 CFU of each strain (producing enterotoxin A, B, C, or D) in BHI was inoculated into two types of commercial cheeses presenting low and high contamination. Therefore, the samples were incubated at 8 °C, 15 °C, and 35 °C for 24, 48 and 72 hours in aerobic and anaerobic condition. The detection and quantification of enterotoxins were tested against toxin A, B, C and D using reverse passive latex agglutination. There was no enterotoxin production at 8 °C in all treatment, consequently, no statistically significant difference was observed. At 15 °C, the SEA production was significantly higher (p<0.05) in BHI broth than in cheese with low contamination in all three times evaluated. Regarding SEB, in aerobic condition at 15 °C after 72 hours, the BHI broth showed significantly higher production than the low contaminated cheese. S. aureus produced a different range of enterotoxin according to the substrate. In BHI, the production was higher than in cheese, suggesting that food substrates more appropriate to analyze the real enterotoxin production. Besides, the microbiota presents can interfere in its production.