Risk of methicillin-resistant Staphylococcus aureus infection after previous infection or colonization.

Studies evaluating the risk of methicillin-resistant Staphylococcus aureus (MRSA)-associated sequelae in colonized or infected inpatients have not extended follow-up into the period after discharge from the hospital. We determined the 18-month risk of MRSA infection among 209 adult patients newly identified as harboring MRSA. Twenty-nine percent of patients (60 patients) developed subsequent MRSA infections (90 infections). These infections were often severe. Twenty-eight percent of infections (25 of 90) involved bacteremia, and 56% (50 of 90) involved pneumonia, soft tissue infection, osteomyelitis, or septic arthritis. Eighty percent of patients (48 of 60) with subsequent MRSA infection developed the infection at a new site, and 49% of new MRSA infections (44 of 90) first became manifest after discharge from the hospital. Accurate assessment of the risk of MRSA-associated sequelae requires prolonged follow-up after discharge.