Spread of methicillin-resistant Staphylococcus aureus (MRSA) among household contacts of individuals with nosocomially acquired MRSA

OBJECTIVE: To determine the frequency with which methicillin-resistant Staphylococcus aureus (MRSA) is spread from colonized or infected patients to their household and community contacts. DESIGN: Retrospective cohort study. SETTING: University hospital. PARTICIPANTS: Household and community contacts of MRSA-colonized or -infected patients for whom MRSA screening cultures were performed. RESULTS: MRSA was isolated from 25 (14.5%) of 172 individuals. Among the contacts of index patients who had at least one MRSA-colonized contact, those with close contact to the index patient were 7.5 times more likely to be colonized (53% vs 7%; 95% confidence interval, 1.1 to 50.3; P = .002). An analysis of antimicrobial susceptibility and DNA fingerprint patterns suggested person-to-person spread. CONCLUSIONS: MRSA colonization occurs frequently among household and community contacts of patients with nosocomially acquired MRSA, suggesting that transmission of nosocomially acquired MRSA outside of the healthcare setting may be a substantial source of MRSA colonization and infection in the community.