Comparison of various screening methods for presumptive diagnosis of significant bacteriuria

Abstract

Background: Urinary tract infection is a common source of bacterial infection among people of any age. Urinalysis is one of the important and useful urological tests for diagnosis of the infection. Microscopic examination of urine, catalase test, and the dipstick urinalyses (leukocyte esterase test and nitrite test) are common tests used for detecting bacteriuria and pyuria. Although culture is the gold standard method for diagnosis of urinary tract infection, the culture is an expensive and time-consuming method. Objective: (1) To compare dipstick urinalysis with microscopic urinalysis, (2) to compare dipstick and microscopic urinalyses results with urine culture results, by calculating performance characteristics of dipstick tests, and (3) to compare catalase test with urine culture results. Materials and Methods: The 1,000 urine specimens were processed by using dipstick and microscopic urinalyses and cultured. Reagent strips reading and microscopic examination were included in laboratory urinalysis in this study. Result: Of 1,000 urine samples of patients, 186 (18.6%) patients revealed urine cultures with significant bacteriuria (105 colonies/mL or greater). Sensitivity and specificity of microscopic urinalysis bacteriuria were 96.77% and 98.52%, respectively. Whereas, in dipstick urinalysis, sensitivity and specificity of nitrite test were 90% and 97% and, in leukocyte esterase test, they were 87% and 95%, respectively. Sensitivity and specificity of catalase test for bacteriuria were 88.63% and 75.86%, respectively. Conclusion: Dipstick test could be used more effectively as office procedure in rural areas where laboratory facility for microscopy and culture is not available for diagnosis of urinary tract infection.