(577) MRSA Decolonization Protocol and its Impact on Negative Predictive Value of MRSA Screens

Introduction: Methicillin resistant staphylococcus aureus (MRSA) infections leads to an increase in mortality, healthcare expenses, and poor outcomes. Thus, a method to reduce MRSA infections is needed. One method is MRSA de-colonization with mupirocin ointment. Charleston Area Medical Center (CAMC) recently adopted a similar protocol on December 19, 2022 which includes 5 days of treatment with topical mupirocin intranasally for patients admitted to an intensive care unit, and/or those with central vascular access. An assessment of whether MRSA screens used for aiding in antibiotic stewardship may be impacted by these protocols is necessary. This retrospective study aimed to look at the difference in NPV (negative predictive value) from MRSA screens for MRSA infections at CAMC following the introduction of MRSA de-colonization protocols.

Methods: This retrospective observational cohort study of patients with MRSA screens between July 1, 2022 – June 31, 2023, at CAMC (Memorial, General, and Teays Valley Hospitals), and with at least one culture collected. Cohort 1, July 1, 2022 – December 19, 2022, included patients whose MRSA screens were obtained prior to the de-colonization protocol initiation. Cohort 2, December 20, 2022- June 31, 2023, included the patients with MRSA screens obtained after the initiation of the MRSA de-colonization protocol.

Results: Among the 328 patients that were included in the study, the NPV was 97.4% and 98% in cohort 1 and cohort 2, respectively. The median days of duration of therapy of MRSA active antimicrobials was 3 days in cohort 1 and 2 days in cohort 2 (p=0.376). The incidence of re-introduction of MRSA active antimicrobials was 25% in cohort 1 and 0% in cohort 2.

Conclusions: Decolonization with mupirocin ointment did not lead to a decreased NPV for MRSA nasal screens in our study population. While patients may have only received a short course of mupirocin prior to the MRSA nasal screen being collected, it is reasonable to say that the use of MRSA nasal screens when collected within 48 hours of hospital admission should not hinder their utilization for de-escalation of MRSA active antimicrobials.