MONDAY, May 17 (HealthDay News) -- Commonly used tests for diagnosing lower urinary tract infections in patients with lower urinary tract symptoms but no dysuria lack sensitivity and should be abandoned, according to research published in the May issue of The Journal of Urology.
Rajvinder Khasriya, of the University College London Medical School, and colleagues conducted a blinded, prospective observational cohort study of urologic patients with lower urinary tract symptoms who did not have dysuria. They collected 508 midstream and 470 catheter urine samples, which were evaluated with standard urinary diagnostic tests, including leukocyte esterase, nitrite dipstick and urine microscopy. For the midstream specimens, the gold standard used to compare the predictive value of these tests was the standard bacterial culture positive at 105 colony forming units (cfu) per ml. For the catheter specimens, the diagnostic tests were also evaluated against an "enhanced" standard of culture positivity of 102 cfu/ml.
The researchers found that, for a midstream urine culture at 105 cfu per ml, leukocyte esterase and microscopic pyuria were each only 56 percent sensitive. The nitrite dipstick test, while highly specific, had only 10 percent sensitivity. For catheter urine culture, sensitivities were only slightly improved. Fifteen percent of the catheter urine cultures were positive using the 105 cfu/ml cut-off, while 29 percent were positive using a 102 cfu/ml cut-off.
"This study was conducted in a normal clinical practice, giving it wide applicability through urological services where the limitations of these tests must be acknowledged. These tests should no longer be recommended for screening. Our understanding of the etiology of important conditions such as overactive bladder may be seriously at fault," the authors write.
Abstract
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