SUMMARY
No U.S. general population-based study has characterized the epidemiology and risk factors, including skin and soft tissue infection (SSTI), for healthcare-associated (HA) and community-associated (CA) methicillin-resistant Staphylococcus aureus (MRSA). We estimated the incidence of HA and CA-MRSA and SSTI over a 9-year period using electronic health record data from Geisinger Clinic in Pennsylvania. MRSA cases were frequency matched to SSTI cases and controls in a nested case-control analysis. Logistic regression was used to assess risk factors, while accounting for antibiotic administration. We identified 1713 incident CA and 1506 HA MRSA cases and 78216 SSTI cases. On average, from 2005–2009, the annual incidence of CA MRSA increased by 34%, HA-MRSA by 7%, and SSTI by 4%. Age, season, community socioeconomic deprivation, obesity, smoking, prior SSTI, and antibiotic administration were identified as independent risk factors for CA-MRSA.