Although being clustered to 15 CCs, 65% of the SABSI isolates clustered to four (CC45, CC15, CC5, and CC30) of the 10 most common human S. aureus CCs (29), and all but one SABSI patient (14/15) had isolates clustering to the same CC in both blood culture and nasal isolates, suggesting endogenous infection. Here, CXCR1 is linked to infection.