Evaluation of early intervention in antimicrobial stewardship for patients with positive blood cultures by introducing Xpert MRSA/SA BC “Cepheid”

Abstract

In Staphylococcus aureus bacteremia (SAB), prompt identification of methicillin-resistant Staphylococcus aureus (MRSA) or methicillin-susceptible Staphylococcus aureus (MSSA) using molecular assays facilitates appropriate antimicrobial treatment. In November 2020, our hospital introduced the Xpert MRSA/SA Blood Culture “Cepheid” (GX), a reagent designed for the GeneXpert system (Beckman Coulter), an automated genetic analyzer. This system enables the identification of methicillin resistance status upon positive blood culture results. In this retrospective study, we divided SAB cases at our hospital into periods before and after GX introduction and evaluated the utility of GX. Following the introduction of GX, cefazolin (CEZ) usage increased, and anti-MRSA drug usage decreased in MSSA cases on positive reporting days. In contrast, CEZ usage decreased, and anti-MRSA drug administration increased for MRSA cases during the same period. Although 30-day mortality rates remained unchanged, the time to fever resolution (37.0°C) decreased, resulting in shorter hospital stays. These findings suggest that the introduction of GX optimized antimicrobial usage by reducing anti-MRSA drug administration in MSSA cases and enabling early administration in MRSA cases, thereby reducing drug costs and contributing to earlier improvement of clinical outcomes.