Accuracy of Automated Flow Cytometry-Based Leukocyte Counts To Rule Out Urinary Tract Infection in Febrile Children: a Prospective Cross-Sectional Study

Abstract

A diagnosis of urinary tract infection (UTI) requires at least 18 h until confirmation of a positive urine culture (1, 2). The growing need to enhance the performance of urine culture combined with the need to free up resources by rejecting negative samples quickly and economically has drawn attention to tests that can be used as initial diagnostic tests to rapidly rule out UTI in a two-tiered diagnostic process (3). For that purpose, several rapid urinary tests are commonly used, including dipstick biochemical analysis of urine for nitrites or leukocyte esterase (LE), and microscopic examination of urine for formed elements, including white blood cells (WBCs) and bacteria (4). In a recent meta-analysis, a positive dipstick for either LE or nitrite had 88% sensitivity and 79% specificity, whereas a nitrite-only positive dipstick had 49% sensitivity and 98% specificity for diagnosing UTI (4). Microscopic analysis of WBCs from centrifuged urine had a lower sensitivity and specificity than dipstick analysis and offered no advantage. However, microscopic examination for the detection of bacteria after Gram stain seems to be the most accurate test, with estimates of 91% sensitivity and 96% specificity (4). However, manual microscopy is technically demanding, and maintaining a 24-h service is restricted by the need for qualified laboratory staff, consumption of resources, and a considerable workload (5).Urinalysis with automated flow cytometers performed by personnel with minimal training provides instant results for bacterial, red blood cell (RBC), and WBC counts (6). Furthermore, the small amount of urine needed (Ϯ1 ml) makes this method suitable for pediatric primary care facilities (5). Several adult studies reported good diagnostic performance of this technique, suggesting that automated flow cytometry might become the reference technique for urinalysis (3,4,(7)(8)(9). However, only a few relatively small studies have investigated the diagnostic performance of this technique in children (5, 10).The present study was designed to compare the diagnostic performance of urinary automated flow cytometry analysis and urinary dipstick analysis of nitrites and LE as screening tests for UTI in a pediatric population. For this purpose, screening with both tests was performed in febrile children in whom UTI was considered a possibility on clinical grounds and for whom a urine sample was sent for culture. Further objectives of this study were to determine the optimal leukocyturia cutoff value to detect a UTI in febrile children, and to model how automated flow cytometry WBC counts perform as a diagnostic test in populations with different disease probabilities of UTI (11).

Evaluation of Urine Procalcitonin, Interleukin-6, Heparin Binding Protein, Leukocyturia, and Bacteriuria for Early Detecting Urinary Tract Infection

“…In this study, there were significant differences on HBP, IL-6, PCT, leukocyturia, and bacteriuria levels between UTI patients with positive culture, UTI patients with negative culture and healthy control group with p value <0.05. The results were consistent with several studies showing that there was a significant increase of IL-6, HBP, PCT, leukocyturia, and bacteriuria levels in patients with UTI compared with healthy control with p-value <0.05 (Kjolvmark et al, 2014;Duong et al, 2016;Manoni et al, 2009 The result of urine positive culture mostly dominated by gram negative bacterial infection as much 86.27 %, while infection of gram-positive bacteria as much 15.69%. The most common bacteria in this study were Escerichia coli (31.37%) followed by Staphylococcus epidermidis (13.73%) and Pseudomonas stutzeri (13.73%).…”

“…Study by Peters et al (2013) showed that an Asian population had higher levels of IL-6 than Europe population (Peters et al, 2013). In developing countries, especially Southeast Asia, the level of infectious disease is high to affect the response of individual infections (Duong et al, 2016). Second, the types of germs that cause infections may be impact on result of this study.…”

Prospective Cohort Study Investigating the Safety and Efficacy of Ambulatory Treatment With Oral Cefuroxime-Axetil in Febrile Children With Urinary Tract Infection

“…A positive urinalysis was defined as a trace or greater result for leukocyte esterase and/or nitrite on dipstick (Medi-test Combi 11; Macherey-Nagel, Düren, Germany), and/or the presence of ≥35 leukocytes/μL of uncentrifuged urine using the automated flow cytometer Sysmex UF-100 (Merck-Eurolab, Leuven, Belgium) ( 14 ). The laboratory staff was blinded to clinical information.…”

Unmet need of antenatal screening for asymptomatic bacteriuria: A risk factor for adverse outcomes of pregnancy

“…Seventy-eight records were retrieved from the electronic database, while 25 studies[13141516171819202122232425262728293031323334353637] were retained for qualitative synthesis [Figure 1]. The researchers had studied 11 individual tests and 7 combinations of various tests [Figure 1].…”