Clinical Utility of Methicillin-Resistant Staphylococcus aureus Polymerase Chain Reaction Nasal Swab Testing in Lower Respiratory Tract Infections

Abstract

ore than 300,000 patients were hospitalized with methicillin-resistant Staphylococcus aureus (MRSA) infections in the United States in 2017, and at least 10,000 of these cases resulted in mortality. 1 While MRSA infections overall are decreasing, it is crucial to continue to employ antimicrobial stewardship tactics to keep these infections at bay. Recently, strains of S. aureus have become resistant to vancomycin, making this bacterium even more difficult to treat. 2 A novel tactic in antimicrobial stewardship involves the use of MRSA polymerase chain reaction (PCR) nasal swab testing to rule out the presence of MRSA in patients with lower respiratory tract infections (LRTI). If used appropriately, this approach may decrease the number of days patients are treated with anti-MRSA antimicrobials. Waiting for cultures to speciate can take up to 72 hours, 3 meaning that patients may be exposed to 3 days of unnecessary broad-spectrum antibiotics. Results of MRSA PCR assay of nasal swab specimens can be available in 1 to 2 hours, 4 allowing for more rapid de-escalation of therapy. Numerous studies have shown