745. Title: Epidemiology of Hospital-onset Bacteremia (HOB) caused by Methicillin-resistant Staphylococcus aureus (MRSA) in a Multi-hospital Health System

Abstract Background Hospital-onset bacteremia (HOB) is a quality metric proposed by CDC. HOB caused by methicillin-resistant Staphylococcal aureus (MRSA) is reported to Centers for Medicare and Medicaid services through the National Healthcare Safety Network (NHSN), yet few studies have described HOB-MRSA epidemiology. Thus, we report HOB-MRSA epidemiology from 2020-2022 at our multi-hospital health system to inform quality improvement initiatives. Methods We used data submitted to the NHSN to prospectively identify HOB-MRSA LabID cases and collected demographic and clinical characteristics from patients’ electronic medical records. Hospital epidemiologists at each of the 9 hospitals adjudicated suspected sources of HOB-MRSA. Annual standardized infection ratios (SIRs) were calculated. Characteristics of HOB-MRSA episodes were analyzed by descriptive statistics. Relevant institutional review boards deemed this study exempt from Human Subjects Research. Results From 2020-2022, 174 (0.029%) HOB-MRSA episodes occurred among 573,433 hospitalizations. Table 1 provides the characteristics of patients with HOB-MRSA and Table 2 provides the SIRS and suspected sources of HOB-MRSA. Overall, 43% of patients were in an ICU, 44% had a central line (CL), and 30% were on a ventilator. The SIR was lowest in 2022. Respiratory sources (non-ventilator and ventilator-associated pneumonia (VAP)) were the most common and declined over time (p=0.002). Suspected sources of HOB-MRSA were unknown for 11% of episodes. Conclusion We found that episodes of HOB-MRSA were attributed to multiple primary sources of infection. Thus, bundle strategies for VAP and CL-associated bloodstream infections, while crucial, are insufficient to reduce all HOB-MRSA. In addition, prevention strategies for patients with skin and soft tissue infections are needed. Our findings highlight the importance of adherence to all device and procedure-related bundles, hand hygiene, cleaning/disinfection, and MRSA decolonization when appropriate. Elucidating the epidemiology of primary infection sources can further tailor prevention strategies for HOB. Disclosures Sorana Segal-Maurer, MD, Gilead Sciences, Inc: Advisor/Consultant|Gilead Sciences, Inc: Honoraria|Janssen: Advisor/Consultant|Janssen: Honoraria|Theratechnologies: Advisor/Consultant|Theratechnologies: Honoraria|Viiv: Advisor/Consultant|Viiv: Honoraria Nishant Prasad, MD, Gilead Sciences, Inc.: Grant/Research Support Lisa Saiman, MD MPH, Merck & Co., Inc,