Clinical and Molecular Epidemiology of Methicillin-ResistantStaphylococcus aureusamong Patients in an Ambulatory Hemodialysis Center

Abstract

Objective.To describe the epidemiology of methicillin-resistantStaphylococcus aureus(MRSA) carriage and transmission in an ambulatory hemodialysis population.Design.Prospective cohort study.Setting.Outpatient hemodialysis facility affiliated with a large academic medical center.Participants.Of the 170 facility patients, 103 (61%) participated in the study.Methods.Swab specimens of the nares, axillae, and vascular access site were collected from participants weekly for 3 weeks and then monthly for 5 months. Demographic and clinical data were collected monthly for 12 months. Molecular analysis of MRSA isolates was performed.Results.The baseline MRSA carriage prevalence was 12%. Factors associated with MRSA carriage included a history of MRSA; failed renal transplantation; hospital admission within 6 months; and receipt of a first-generation cephalosporin, cefepime, or vancomycin. Six subjects acquired MRSA after enrollment (incidence, 1.2 per 100 patient-months at-risk; overall prevalence, 18%). Molecular analysis suggested that transmission occurred within the facility. The incidence of MRSA infection among carriers was 1.76 per 100 patient-months. Community-associated strains (ie, USA300) were isolated from 28% of carriers and at least 25% of infections.Conclusions.The prevalence of MRSA carriage and the incidence of infection among carriers were high among ambulatory hemodialysis patients, and community-associated MRSA was responsible for a large portion of the MRSA burden. A relatively high rate of MRSA acquisition was observed, with indirect evidence of intrafacility transmission. Additional studies are needed to confirm these findings and to identify effective and feasible methods to prevent MRSA transmission and infection among hemodialysis patients.