Clinical Utility of Methicillin-Resistant <i>Staphylococcus aureus</i> Polymerase Chain Reaction Nares Swabs in Burn-Injured Patients

Methicillin-resistant Staphylococcus aureus (MRSA) is a common pathogen in burn-injured patients. Many studies have evaluated the overall utility of MRSA nares polymerase chain reaction (PCR) swabs for antimicrobial stewardship; however, there is a paucity of data in burns. This study evaluated the clinical utility of MRSA PCR in burn-injured patients at an academic medical center. This retrospective, single-center chart review included admitted adult burn-injured patients from July 2020 to June 2024. The primary objective was to determine the overall negative predictive value (NPV) of MRSA PCR in patients with burn injuries for suspected MRSA infections. Secondary objectives included determining the sensitivity, specificity, NPV, and positive predictive value (PPV) of MRSA PCR for specific culture types. There were 89 patients, and 289 cultures were included. The overall prevalence of MRSA positive cultures was 13.4% for the study period. For the primary outcome, the NPV of MRSA PCR was 98.3% (95% confidence interval, 95.5%-99.5%). For the whole cohort the PPV was 22.5%, sensitivity was 73.4%, and specificity was 86.1%. The total cost of vancomycin therapy (doses and levels) was US $37 935.75, which was estimated using average wholesale price. A cost avoidance of US $378.15 per patient was estimated for patients not meeting criteria for vancomycin therapy. Overall, this study found a high NPV for MRSA PCR in burn-injured patients with suspected infections. In addition, MRSA PCR may be used along with other clinical markers to decrease the use of antimicrobials targeting MRSA, which may help decrease the cost of therapy.