Metabolites of non-aureus staphylococci affect the ability of Staphylococcus aureus to adhere to and internalize into bovine mammary epithelial cells

This study investigated whether cell-free supernatants (SN) from four bovine non-aureus staphylococcal (NAS) isolates prevent Staphylococcus aureus adhesion to and internalization into bovine mammary epithelial cells (MAC-T cells) and if so, to determine whether such effects were potentially associated with the S. aureus accessory gene regulator (agr) system. Overall, we demonstrated that all SN obtained from the NAS isolates promoted adhesion of a S. aureus agr(+) strain to, yet reduced the internalization into MAC-T cells, while similar effects were not observed for its agr(−) mutant strain. Our findings provide novel anti-virulence strategies for treating and controlling bovine S. aureus mastitis.