Urine dipstick test for diagnosing urinary tract infection

Abstract

Background Urinary tract infection (UTI) is a common disease in children. Approximately 3-5% of girls and 1 % of boys develop a UTI. In children, prompt treatment is essential because UTI may be a risk factor for developing renal insufficiency or end stage renal disease. Howevet; prompt treatment depends on having a rapid diagnosis. Urine dipstick testis a useful and commonly used because it is low cost and gives rapid results, compared to urine cultures for diagnosing UTis. However, the diagnostic accuracy of the urine dipstick test is debatable. Objective To compare urine dipstick test (leukocyte esterase, nitrite, and combined leukocyte es terase and nitrite) to urine culture for diagnosing UTis. Methods A diagnostic study was held in H. Adam Malik Hospital from May to June 2010. There were 70 children aged 2 to 14 years and recruited by consecutive sampling. Two midstream urine specimens were collected from subjects after cleaning the external urethral orifice. The first specimen was used for urine dipstick testing for leukocyte esterase and nitrite. The second urine specimen was cultured in the laboratory. Urinalysis for leukocyte esterase and nitrite studies were performed with fresh and uncentrifuged urine. Leukocyte esteras e and nitrite caused a change in dipstick color apparent within 2 minutes. Urinalyses were considered to be positive for UTI if either leukocyte esterase or nitrite were positive. The results of urine culture were used as the golden standard. Results The sensitivities of leukocyte esterase and nitrate tests were 90 .5% and 73.8%, respectively. However, the sensitivity for combined leukocyte esterase and nitrite test was 96.4%. Nitrite test was more specific (60.7%) than the leukocyte esterase test (39.3%). The specificity of both tests taken together was 64.3% . For leukocyte esterase alone, nitrate alone, and the two combined the positive predictive values (PPV) were 69.1 %, 73.8%, and 64.3.%, respectively, and the negative predictive values (NPV) were 73.3%, 60.7%, and 96.4%, respectively. Conclusion Urine dipstick test for leukocyte esterase and nitrite combined may be a good alternative diagnostic test for UTis in children than leukocyte esterase or nitrite by themselves in areas with limited resources.

Keywords

• dipstick urine, urine culture, urinary tract infection