Decolonization with Mupirocin and Subsequent Risk of Methicillin-Resistant Staphylococcus aureus Carriage in Veterans Affairs Hospitals

INTRODUCTION Hospital-acquired methicillin-resistant Staphylococcus aureus (MRSA) infections remain one of the leading causes of preventable patient mortality in the US. Eradication of MRSA through decolonization could prevent both MRSA infections and transmission; however, there is currently no consensus within the infectious disease community on the proper role of decolonization in the prevention of infections. The purpose of this study was to assess the impact of decolonization with mupirocin on subsequent MRSA carriage. METHODS Patients included in this study were those with an inpatient admission to a Department of Veterans Affairs (VA) hospital between January 1, 2008 and December 31, 2009 who had a positive MRSA screen on admission and a subsequent re-admission during the same time period. Exposure to mupirocin on the initial hospital admission was measured using Barcode Medication Administration data and MRSA carriage was measured using microbiology text reports and lab data containing results from surveillance swabs collected from the nares. Chi-square tests were used to test for differences in re-admission MRSA carriage rates between mupirocin-receiving and non-mupirocin-receiving patients. RESULTS Of the 25,282 MRSA-positive patients with a subsequent re-admission included in the present study cohort, 1,183 (4.7%) received mupirocin during their initial hospitalization. Among the patients in the present study cohort who were re-admitted within 30 days, those who received mupirocin were less likely to test positive for MRSA carriage than those who did not receive mupirocin (27.2% vs. 55.1%, P < 0.001). The proportion of those who tested positive for MRSA during re-admissions that occurred 30-60 days, 60-120 days, and >120 days were 33.9, 37.3, and 41.0%, respectively, among mupirocin patients and 52.7%, 53.0%, and 51.9%, respectively, for patients who did not receive mupirocin (P < 0.001 at each time point). CONCLUSION Patients decolonized with mupirocin in VA hospitals were less likely to be colonized with MRSA on re-admission as long as 4 months after decolonization.