We investigated the characteristics of Staphylococcus aureus isolates causing bovine subclinical mastitis (SCM), and their genetic relatedness with the isolates obtained from Egyptian cheese. Twenty-five S. aureus isolates were identified from 150 SCM milk and 75 cheese samples. The antibiogram revealed multidrug-resistant (MDR) isolates. Fifteen isolates were categorised as methicillin-resistant. Antimicrobial resistance and virulence genes were detected. Spa typing and SCCmec classification were performed. More than 50% of isolates were found carrying human-specific virulence determinants, while other isolates characterised were presumed to be of bovine-origin. Spa-types t304, t688, t084 corresponded isolates from SCM milk and cheese samples; the similar genotypes from SCM and cheese displayed divergence in virulence traits. Moreover, our results revealed the novel spa-type t18546. Animals and dairy food could be a reservoir for transformative changes in S. aureus virulence, leading to the emergence of virulent MDR strains that may become potential public-health threats.
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