Severe acute respiratory syndrome coronavirus 2, the virus responsible of the current COVID-19 pandemic, has limited impact in the pediatric population. Children are often asymptomatic or present mild flu-like symptoms. We report the case of a COVID-19-infected adolescent presenting severe rhabdomyolysis and acute kidney injury without any fever or respiratory symptoms.

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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).