Should the methicillin-resistant Staphylococcus aureus carriage status be used as a guide to treatment for skin and soft tissue infections?

Objective: Previous skin carriage of methicillin-resistant Staphylococcus aureus (MRSA) leads frequently to empiric antibiotic MRSA coverage for skin & soft tissue infections. Methods: Retrospective cohort study of orthopaedic patients hospitalized at Geneva University Hospitals (MRSA prevalence; 30%); community-acquired MRSA excluded. Results: A total of 378 skin and soft tissue infections in 346 patients were retrieved. Overall cure was achieved in 330 episodes (87%) after a median antibiotic administration of 15 days. Among all episodes, 102 revealed a positive current MRSA status (during 2 weeks preceding infection; 27%) and 70 (19%) were MRSA carriers in the past. Sensitivity, specificity, positive and negative predictive values of current MRSA skin carriage to predict abscesses due to MRSA were 0.68, 0.77, 0.19, and 0.97, respectively. Fifty-four current MRSA carriers (54/102, 53%) and 30 past carriers (43%) were successfully treated with a non-MRSA antibiotic agent. In multivariate Cox regression analysis, anti-MRSA coverage (hazard ratio 1.2, 95%CI 0.5-2.8) and duration of antibiotic therapy (HR 1.0, 95%CI 0.96-1.02) did not influence treatment failure among patients with positive MRSA carriage. Conclusions: Current or past HA-MRSA skin carriage poorly predicts the need for anti-MRSA coverage for the antibiotic treatment of skin and soft tissue infections in hospitalized orthopaedic patients. (C) 2012 The British Infection Association. Published by Elsevier Ltd. All rights reserved.