| Summary: | Food, particularly milk and cheese, may be a reservoir of multi-drug resistant <i>Staphylococcus aureus</i> strains, which can be considered an important issue in terms of food safety. Furthermore, foods of animal origin can be a cause of staphylococcal food poisoning via the production of heat-stable enterotoxins (SE). For this reason, we investigated the prevalence of and characterized <i>Staphylococcus aureus</i> strains isolated from milk and fresh soft cheese obtained from farms located in Wielkopolskie and Zachodniopomorskie Provinces in Poland. Overall, 92% of <i>S. aureus</i> isolates were positive for at least one of the 18 enterotoxin genes identified, and 26% of the strains harbored 5 to 8 enterotoxin genes. Moreover, the <i>S. aureus</i> strains contained genes conferring resistance to antibiotics that are critically important in both human and veterinary medicine, i.e., β-lactams (<i>mecA</i>), aminoglycosides (<i>aac</i>(<i>6</i>′)/<i>aph</i>(<i>2</i>″), <i>aph</i>(<i>3</i>′)<i>-IIIa</i>, <i>ant</i>(<i>4</i>′)<i>-Ia</i>) and MLS<sub>B</sub> (<i>erm</i>(<i>A</i>), <i>msr</i>(<i>A</i>), <i>lun</i>(<i>A</i>)). The antimicrobial susceptibility of <i>S. aureus</i> to 16 antibiotics representing 11 different categories showed that 74% of the strains were resistant to at least 1 antibiotic. Moreover, 28% of the strains showed multidrug resistance; in particular, two methicillin-resistant <i>S. aureus</i> strains (MRSA) exhibited significant antibiotic resistance. In summary, our results show that dairy products are contaminated by <i>S. aureus</i> strains carrying genes encoding a variety of enterotoxins as well genes conferring resistance to antibiotics. Both MRSA strains and MSSA isolates showing multidrug resistance were present in foods of animal origin.
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