Background: Infections of cerebrospinal fluid (CSF), peritoneal and pleural fluids often result in severe morbidity and mortality. Cytometric analysis, cell count, and cell differentiation is supportive in rapid clinical decision. The aim of this study is to evaluate the performance of Sysmex UF-5000 (Sysmex Co., Kobe, Japan) in body fluid (BF) mode for white blood cells and bacterial counting and compare the results with manual microscopy, gram staining, and culture as reference method.
Methods: A total of 634 body fluid samples (433 CSF, 100 pleural, and 101 peritoneal fluid) submitted to our clinical microbiology laboratory between December 2018 and January 2020 were enrolled in the study. Specimens were analyzed for white blood cell (WBC) counts with Sysmex UF-5000-BF mode. The results were grouped into five categories and compared with the conventional methods as reference method. The relationship between culture results and Sysmex UF5000-BF bacterial load and WBC count were evaluated for the detection of infection.
Results: The categorical agreement of UF 5000-BF mode was very strong for CSF (correlation coefficient: 0.70, p < 0.05) and good agreement was found for pleural and peritoneal samples (correlation coefficient: 0.63, p < 0.05). Sensitivity was 100% and specificity was 64% in pleural samples. For ascites sensitivity and specificity were found as 94.1% and 77.4%, and for CAPD samples as 100% and 81,2% respectively. Bacterial and WBC count with flow cytometry was higher among culture positive samples (p < 0.05). The same significant difference was detected between the UF 5000-BF bacterial counts and the samples in which bacteria were detected in the gram preperation (p < 0.05). WBC count by UF-5000-BF was also higher among culture positive compared to culture negative samples (p < 0.05).
Conclusions: Our results demonstrated that the flow cytometric method, Sysmex UF-5000 body fluid (BF) mode, can be an alternative particularly in CSF samples. Detection of 100% sensitivity in peritoneal and pleural samples can prevent unnecessary antibiotic treatment and possible resistance development. Besides, automated bacterial counting can be used for rapid prediction of a positive body fluid culture.