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Automated urine cytometry, point-of-care dipstick tests perform well
Automated leukocyte and bacterial counts performed well in the diagnosis of urinary tract infection in pediatric patients. However, point-of-care dipsticks could also be accurate enough to use in clinical settings that require immediate decision making, according to recent study findings in Pediatrics.
Conducted by John T. Kanegaye, MD, of the University of California San Diego School of Medicine, and colleagues, the study examined the diagnostic performance of these methods in a convenience sample of febrile children younger than 48 months. A small but growing reliance on automated cytometry was cited as an impetus for this work, as well as a lack of studies evaluating the methods in children specifically.
A positive urine culture was defined as a urinary bacterial growth greater than or equal to 50,000/mL. Of the eligible children who underwent urethral catheterization (n=324), 42 (12%) had urinary bacterial growth greater than 50,000/mL.
Automated leukocyte counts recorded sensitivities and specificities of 86% and 98% for bacterial counts greater than or equal to 100/mcL, and 98% and 98% for those greater than or equal to 250/mcL.
Automated bacterial counts at the 100/mcL cutoff had a sensitivity and specificity of 100% and 95%, respectively. Counts at 250/mcL recorded both sensitivity and specificity at 98%.
Point-of-care urine dipstick tests with one or more leukocyte esterase or positive nitrite had a sensitivity of 95% and a specificity of 98%.
The combination of bacterial and white blood cell counts did not produce more accurate results than bacterial counts alone. Although specificities reached as high as 99.3%, sensitivities ranged from 79% to 83%.
With this data, the researchers concluded that, at the 250/mcL bacterial index, automated leukocyte and bacterial count results exceeded those of other methods with the added benefit of labor reduction. Automated white blood cell counts were less sensitive, but were considered useful at 100/mcL or greater bacterial counts.
Additionally, the combination of point-of-care dipstick leukocyte esterase and nitrites measurements “had acceptable diagnostic performance and may be an attractive alternative option when manual or automated microscopic urinalysis is not available or practical,” the researchers wrote.
Disclosure: The researchers report no relevant financial disclosures.