Screening of urinary tract infections in children using fluorescent flow cytometry: A single-center study

Introduction/Objective. Urinary tract infections (UTIs) in children represent a significant public health problem due to their high prevalence and the need for timely diagnosis and adequate treatment. Automated methods using fluorescent flow cytometry are increasingly being used in laboratories for the screening of UTIs. The aim of this study was to determine the cut-off values for leukocyturia and bacteriuria using fluorescent flow cytometry for the screening of urinary tract infections in the pediatric population. Methods. A total of 821 urine samples were cultured, of which 366 samples met the criteria for fluorescent flow cytometry on the automated Sysmex UF-4,000 analyzer. The number of leukocytes and bacteria was compared with the culture results. Results. Of the total urine cultures tested, 209 (25.5%) were positive, and 599 (73%) were negative. There was a statistically significant difference in the prevalence of uropathogens according to the age of the children (p < 0.001). The area under the curve (AUC) for leukocyte count was 0.77 (95% CI: 0.71-0.84), while the AUC for bacterial count was 0.85 (95% CI: 0.81-0.89). A low negative likelihood ratio (0) was observed at the cut-off for bacteria of 40.1, and the negative predictive value was high (between 91% and 99%). Conclusion. Determination of leukocyte and bacterial counts in urine in children using fluorescent flow cytometry can serve as an initial test when deciding on urine culture in microbiological laboratories. These results may indicate the necessity of reducing unnecessary urine cultures while providing faster confirmation of negative test results.