Community-acquired methicillin-resistant Staphylococcus aureus in a rural American Indian community

Context Until recently, methicillin-resistant Staphylococcus aureus (MRSA) infections have been acquired primarily in nosocomial settings. Four recent deaths due to MRSA infection in previously healthy children in the Midwest suggest that serious MRSA infections can be acquired in the community in r ural as well as urban locations. Objectives To document the occurrence of community-acquired MRSA infections and evaluate risk factors for community-acquired MRSA infection compared w ith methicillin-susceptible S aureus (MSSA) infection. Design Retrospective cohort study with medical record review. Setting Indian Health Service facility in a rural midwestern American India n community. Patients Patients whose medical records indicated laboratory-confirmed S au reus infection diagnosed during 1997. Main Outcome Measures Proportion of MRSA infections classified as community acquired based on standardized criteria; risk factors for community-acquir ed MRSA infection compared with those for community-acquired MSSA infection ; and relatedness of MRSA strains, determined by pulsed-field gel electroph oresis (PFGE). Results Of 112 S aureus isolates, 62 (55%) were MRSA and 50 (45%) were MSSA . Forty-six (74%) of the 62 MRSA infections were classified as community ac quired. Risk factors for community-acquired MRSA infections were not signif icantly different from those for community-acquired MSSA. Pulsed-field gel electrophoresis subtyping indicated that 34 (89%) of 38 community-acquired MRSA isolates were clonally related and distinct from nosocomial MRSA isola tes found in the region. Conclusions Community-acquired MRSA may have replaced community-acquired MS SA as the dominant strain in this community. Antimicrobial susceptibility p atterns and PFGE subtyping support the finding that MRSA is circulating bey ond nosocomial settings in this and possibly other rural US communities.