Methicillin-susceptible Staphylococcus aureus nasal colonization and the risk of subsequent methicillin-resistant Staphylococcus aureus infections among hospitalized patients

Few data exist on the risk of methicillin-resistant Staphylococcus aureus (MRSA) infections among known methicillin-susceptible S. aureus (MSSA) carriers. In a cohort of 2991 hospitalized MSSA carriers, 22 (22%) of 98 S. aureus infections that occurred within a subsequent 6-month period were caused by MRSA. Recent fluoroquinolone use was an independent predictor of MRSA infections (P < .001).