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

Objective: To assess the utility of methicillin-resistant Staphylococcus aureus (MRSA) polymerase chain reaction (PCR) nasal swab testing in patients with lower respiratory tract infections (LRTI). Design and setting: Multicenter, retrospective, electronic chart review conducted within the Hartford HealthCare system. Participants: Patients who were treated for LRTIs at the Hospital of Central Connecticut or Hartford Hospital between July 1, 2018, and June 30, 2019. Measurements: The primary outcome was anti-MRSA days of therapy (DOT) in patients who underwent MRSA PCR testing versus those who did not. In a subgroup analysis, we compared anti-MRSA DOT among patients with appropriate versus inappropriate utilization of the MRSA PCR test. Results: Of the 319 patients treated for LRTIs, 155 (48.6%) had a MRSA PCR ordered, and appropriate utilization occurred in 94 (60.6%) of these patients. Anti-MRSA DOT in the MRSA PCR group (n = 155) was shorter than in the group that did not undergo MRSA PCR testing (n = 164), but this difference did not reach statistical significance (1.68 days [interquartile range {IQR}, 0.80-2.74] vs 1.86 days [IQR, 0.56-3.33], P = 0.458). In the subgroup analysis, anti-MRSA DOT was significantly shorter in the MRSA PCR group with appropriate utilization compared to the inappropriate utilization group (1.16 [IQR, 0.44-1.88] vs 2.68 [IQR, 1.75-3.76], P < 0.001). Conclusion: Appropriate utilization of MRSA PCR nasal swab testing can reduce DOT in patients with LRTI. Further education is necessary to expand the appropriate use of the MRSA PCR test across our health system.