The Epidemiology of Methicillin-Resistant Staphylococcus aureus on a Burn Trauma Unit

Abstract

OBJECTIVE We assessed the frequency and relatedness of methicillin-resistant Staphylococcus aureus (MRSA) isolates to determine whether healthcare workers, the environment, or admitted patients could be a reservoir for MRSA on a burn trauma unit (BTU). We also assessed risk factors for MRSA colonization among BTU patients. DESIGN Prospective cohort study and surveillance for MRSA carriage. SETTING BTU of a Midwestern academic medical center. PATIENTS AND PARTICIPANTS Patients admitted to a BTU from February 2009 through January 2010 and healthcare workers on this unit during the same time period. METHODS Samples for MRSA culture were collected on admission from the nares and wounds of all BTU patients. We also had collected culture samples from the throat, axilla, antecubital fossa, groin, and perianal area of 12 patients per month. Samples collected from healthcare workers' nares and from environmental sites were cultured quarterly. MRSA isolates were typed by pulsed-field gel electrophoresis. RESULTS Of 144 patients, 24 (17%) carried MRSA in their nares on admission. Male sex (odds ratio [OR], 5.51; 95% confidence interval [95% CI], 1.25-24.30), admission for necrotizing fasciitis (OR, 7.66; 95% CI, 1.64-35.81), and MRSA colonization of a site other than the nares (OR, 23.40; 95% CI, 6.93-79.01) were independent predictors of MRSA nasal carriage. Cultures of samples collected from 4 healthcare workers and 4 environmental cultures had positive results. Two patients were colonized with strains that were indistinguishable from strains collected from a healthcare worker or the environment. CONCLUSIONS Patients were a major reservoir for MRSA. Infection control efforts should focus on preventing transmission of MRSA from patients who are MRSA carriers to other patients on the unit.