Positive clinical risk factors predict a high rate of methicillin-resistant Staphylococcus aureus colonization in emergency department patients

Background: This study was undertaken to determine the rate of methicillin-resistant Staphylococcus aureus (MRSA) colonization predicted by clinical risk factors compared with determination by nasal swab culture and polymerase chain reaction in emergency department patients. Methods: From November 2009 to March 2011, patients seen in the emergency department were studied prospectively. The risk of MRSA colonization was determined by clinical risk factors, and both surveillance cultures and a polymerase chain reaction assay were performed in each patient. Results: A total of 277 patients was enrolled, and 31.4% (87/277) of patients had a positive surveillance culture or a MRSA polymerase chain reaction assay. The rate of colonization in patients with high-risk factors included the following: past history of colonization/infections, 60.0%; history of previous antibiotic use, 47.2%; more than 30 days hospitalization in the past 3 months, 43.9%; more than 10 days hospitalization in the past 3 months, 41.7%; and a history of hospitalization because of acute illness, 40.0%. Conclusion: The prevalence rate of colonization in patients with a high risk of MRSA colonization exceeded 30%. Active surveillance cultures should be considered in patients at high risk for MRSA colonization.