The Leucocyte Cell Population Data as Measured by the Sysmex XN-Series Hematology Analyzer Changes More Rapidly Over Time Than Other Biomarkers During the Treatment of Bacteremia

Introduction: Cell population data (CPD) from the Sysmex XN-Series hematology analyzer have attracted attention as a new leukocyte biomarker in the field of infectious diseases. For CPD, we focused on the fluorescent light distribution of the neutrophil area (NE-WY) and recently reported that it is useful for the early diagnosis of bacteremia. In clinical practice, the rapid assessment of the effectiveness of antibiotic treatment is as important as the early recognition of bacteremia, but it is still unclear whether NE-WY is useful. Methods: We compared the time-dependent changes in NE-WY with parameters commonly used in 54 patients with bacteremia who responded well to initial antibiotic treatment. Results: NE-WY peaked approximately 1 day earlier than C-reactive protein (CRP) and returned to baseline levels significantly earlier. Additionally, NE-WY fluctuated in a similar manner as white blood cells (WBCs) and neutrophils (Neut), but NE-WY had narrower error bars and tended to reach a plateau at the reference value more quickly. Conclusion: This is the first report to demonstrate that NE-WY is a highly useful biomarker not only for diagnosing bacteremia but also for assessing the therapeutic efficacy of antibiotics. NE-WY changes more rapidly over time than other biomarkers during the treatment of bacteremia. Thus, NE-WY has the potential to become a key biomarker in the field of infectious diseases.