P-1679. Neutrophil-related Cell Population Data as an Immediate Biomarker for the Assessment of Therapeutic Response in Methicillin-Resistant Staphylococcus aureus (MRSA) Bacteremia

Abstract Background MRSA bacteremia requires early anti-MRSA therapy, as beta-lactams are ineffective; delays for pathogen identification and susceptibility results can worsen outcomes. Rapid biomarkers are thus essential. Cell population data (CPD), captured via flow cytometry by automated hematology analyzers, appears earlier than conventional laboratory changes but is not reported to clinicians. CPD is readily available at no extra cost and shows promise for early exacerbation detection, though its utility remains underexplored.Figure 1:Study Flowchart for Classification of MRSA Bacteremia Patients Based on Initial Antimicrobial Therapy to Evaluate the Utility of Cell Population Data (CPD)Abbreviations: Abx, antibiotic; CBC, complete blood countTable 1:Comparison of Patient Characteristics Between the Appropriate Therapy Group (AT Group; Anti-MRSA Agents Initiated) and the Inappropriate Therapy Group (IT Group; Non-Anti-MRSA Antibiotics)1. Statistical analyses were performed using Stata/BE 18 (StataCorp., College Station, TX, USA).Continuous variables were analyzed using the t-test, and binary or categorical variables usingFisher’s exact test. A two-sided p-value of