The exfoliative toxin A gene (eta), known for causing staphylococcal scalded skin syndrome, and the transcriptional Repressor SaPI gene (stl), which controls the retention of the Staphylococcus aureus pathogenicity islands (SaPIs) in the host chromosome, were only found in the genomes of strains associated with clinical mastitis. Here, EDNRA is linked to mastitis.