Evaluation of rapid screening methods in the diagnosis of urinary tract infection

Abstract

Introduction: Urinary Tract Infection (UTI) is one of the most common bacterial infection encountered in clinical practice. Even though urine culture is considered as the gold standard in detection of bacteriuria, many alternative screening methods like urine microscopy, chemical analysis using dipstick method and Gram’s staining have been evaluated which are more economical and rapid. Hence, this study was undertaken to evaluate various screening methods in the rapid diagnosis of Urinary Tract Infections. Objectives: To evaluate Gram staining of urine, leucocyte esterase and nitrite dipstick test methods in the rapid diagnosis of Urinary Tract Infections. Materials and Methods: All urine samples received at Microbiology laboratory, McGann hospital, attached to Shimoga Institute of Medical Sciences, during study period was subjected to Gram staining, leucocyte esterase and nitrite dip stick test along with culture. Results of these tests were compared to culture results. Sensitivity and specificity of the tests was determined taking culture as standard. Results: A total of 560 urine samples were processed. Culture showed significant bacteriuria in 210 cases. The sensitivity of urine microscopy was 70.9%, leucocyte esterase test was 98% and nitrite test was 74.8%. Whereas the specificity of urine microscopy was 70%, leucocyte esterase test was 79.1% and nitrite test was 98.8%. Similarly, the sensitivity of combined leucocyte esterase and nitrite tests was 90.9% and specifity was 97.4%. Sensitivity and specificity of all the three screening tests combined were 95.7% and 94.8% respectively. Conclusion: Screening tests such as, Urine microscopy by Gram’s staining, Leucocyte esterase and nitrite dipstick test in combination can be used routinely to exclude bacteriuria. Urine culture can be employed only in the screening tests positive cases and in symptomatic cases irrespective of test results, thereby making diagnosis of UTI cost effective and rapid. Keywords: Bact