SRI and infection: We detected three major genetic events along the evolutionary history of ST9: the loss of the IEC genes (scn, chp, and sak), which were reported to contribute to virulence in human infections, the acquisition of the SaPIbov4-like element-encoding vwb gene, which is an animal-specific virulence factor responsible for the clotting of animal plasma, and the acquisition of antibiotic resistance genes, including SCCmec, QRDR mutations and the MDRST9 genetic elements.