Clinical Utility of a Nasal Swab Methicillin-resistant Staphylococcus Aureus Polymerase Chain Reaction Test in Intensive and Intermediate Care Unit Patients with Pneumonia

This retrospective study aimed to validate the concordance between nasal swab methicillin-resistant Staphylococcus aureus (MRSA) polymerase chain reaction (PCR) test and respiratory culture and to determine the number of potentially preventable days of anti-MRSA therapy in patients with pneumonia. Two hundred adult inpatients in the intensive and intermediate care units were included. The nasal swab MRSA PCR test was positive in 55 (27.5%) patients. MRSA was isolated from respiratory culture in 21 (10.5%) patients. The nasal swab MRSA PCR test demonstrated 90.5% sensitivity, 79.9% specificity, 34.5% positive predictive value, and 98.6% negative predictive value. Anti-MRSA therapy was initiated in 168 (84%) patients. Patients in the study received a combined 782days of anti-MRSA therapy; 300days were considered potentially preventable. This study suggests that the nasal swab MRSA PCR test may be used to guide discontinuation of anti-MRSA antibiotics in patients with clinically confirmed pneumonia in the intensive or intermediate care units.