Population structure and exotoxin gene content of methicillin-susceptible Staphylococcus aureus from Spanish healthy carriers

► The population structure of Staphylococcus aureus from human carriers was studied. ▶ Isolates with genetic backgrounds of hospital-acquired isolates were detected. ► Virulence determinants in commensal S. aureus increased in number over time. ► Results support the role of nasal colonization in the spread of S. aureus.