Evaluation of urine strip test for the diagnosis of urinary tract infection at Police General Hospital

Abstract

     This study was designed to evaluate the diagnostic accuracy of the rapid urine strip test, leukocyte esterase and nitrite to predict urinary tract infection by comparison with the gold standard of urine culture and number of white blood cells in urine. Urine samples of 518 suspected patients were collected from in patient department (IPD) of the Police General Hospital during September 2008 to February 2009. Urine analysis and cultivation were performed in all samples. It was found that 239 out of 581 samples (41.1%) were positive with bacterial culture (≥ 105colony/ml of urine) and E.coli was found predominately. Leukocyte esterase, nitrite and WBC count (>5 WBC/HPF) were positive in 207 (86.6%), 57 (23.8%), and 188 (78.7%) cases out of 239, respectively. Sensitivity of those tests was 86.6%, 23.8%, and 78.7%, respectively. Specificity was 50.9%, 98.2%, and 67.8%, respectively with positive predictive value was 55.2%, 90.5%, and 63.1%, respectively. Sensitivity, specificity and positive predictive value were also determined when 2 tests were used in combination. We found that combination of nitrite and leukocyte esterase showed sensitivity, specificity and positive predictive value of 88.7%, 50.6%, and 55.6%. In contrast, combination of leukocyte esterase and WBC count demonstrated sensitivity, specificity and positive predictive value of 89.1%, 48.5% and 54.7%, respectively. In addition, when data from 3 tests, nitrite, leukocyte and WBC were used, sensitivity, specificity and positive predictive value was 90.3%, 51.8%, and 54.9%, respectively. Taken together, we concluded that data of urine strip tests together with WBC count would be useful in screening of urinary tract infection before doing urine cultivation.