Methicillin-resistant Staphylococcus aureus (MRSA) screening upon inpatient hospital admission: Is there concordance between nasal swab results and samples taken from skin and soft tissue?

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) infections are associated with increased mortality and healthcare costs. In 2007, a Veterans' Affairs (VA) hospital implemented a MRSA nasal screening program, following a nationwide VA mandate, in an effort to reduce healthcare-associated MRSA infections. To evaluate the correlation between the nasal screening results for MRSA and culture results of wound and tissue sites. This retrospective study was conducted on inpatients at our VA hospital. Patients were included if they had undergone nasal screening for MRSA plus culture of a wound or tissue site within 30 days of hospital admission. In total, 337 patients underwent nasal screening and wound culture and 211 underwent nasal screening and wound and tissue cultures. The prevalence of MRSA nasal colonization was 14.2% for wound samples and 15.2% for tissue samples. The sensitivities of MRSA nasal screening for detecting MRSA were 64.6% for wound cultures and 65.5% for tissue cultures. Specificities were 86.2% and 88.8% for wound and tissue cultures, respectively. The positive predictive values (PPVs) were 43.7% and 51.2% for wound and tissue cultures, respectively, and the negative predictive values (NPVs) were high at 93.6% and 93.5%, respectively. In cases of wound or tissue samples for which culture results are pending, a negative MRSA nasal swab may be a component of the decision to withhold or discontinue MRSA-active agents.