Correlation of Nitrite, Leucocyte Esterase and Protein Detection to Diagnosis of Urinary Tract Infections.

Aim: To determine the relationship between detection of nitrite, Leucocyte esterase (LE) and protein in urine and significant bacteriuria. Study Design: Cross-sectional descriptive study. Place and Duration of Study: Department of Medical Microbiology and Parasitology, University of Port Harcourt Teaching Hospital, between March and September 2015. Methodology: 240 urine samples were analyzed. Dipstick analysis using Combi-UriScreen 10SL reagent strips (Axiom Medical limited, UK) and culture for significant bacteriuria were performed according to manufacturer’s instruction/ using standard protocols. Data was coded, entered into Microsoft Excel ® version 2010 and analysed using Epi-Info version 7.02. Categorical data were presented as frequencies and percentages using tables. Univariate analysis using logistic regression (Odds Ratio) was used to determine the association between the presence of nitrite, LE and protein and significant bacterial yield in urine. A P-value of ≤ 0.05 was considered statistically significant. Likelihood ratios were calculated. Results: 23 (23.2%) out of 99 samples with significant bacteriuria were nitrite positive, while 42 (42.4%) and 45 (45.5%) were positive for leucocyte esterase and protein respectively. Nitrite (P = 0.001, OR = 5.03, 95% CI = 2.02-12.93) and leucocyte esterase positivity (P = 0.001, OR = 3.59, 95% CI = 1.91-6.80) were significantly associated with significant bacteriuria while proteinuria was not (P = 0.989, OR = 1.03, 95% CI = 0.60-1.79). Nitrite positivity alone had the best positive likelihood ratio (4.09, 95% CI: 1.91, 8.78) followed by the combination of nitrite and LE positivity (3.65, 95% CI: 1.90, 7.03). Conclusion: The use of dipstick analysis of urine as a screening tool for samples to be cultured may be a very effective way of reducing laboratory costs and wastage of man hours, which both ultimately improve the effectiveness of clinical laboratories especially in resource-poor settings.

Evaluation of the urine dipstick analysis for detection of bacteriuria.

This retrospective study was performed to evaluate the urine dipstick [ Leukocyte esterase and nitrite test ] for detection of bacteriuria and pyuria. Of the 1000 specimens, 296 [ 29.6% ] had positive culture results. The dipstick[ either leukocyte esterase or nitrite test ] test for detection of bacteriuria had a sensitivity of 85%, specificity of 51%, positive predictive value of 42% and negative predictive value of 89%, and the leukocyte esterase test for the detection of pyuria had a sensitivity of 96%, specificity of 73%, positive predictive value of 75% and negative predictive value of 95%. The sensitivity and negative predictive value of the dipstick test in the pediatric group was the lowest values when compared with the other groups. We conclude that, 1.) The dipstick test may be used as a screening test for pyuria. 2.) This test can not be used as a screening test for urinary tract infection [UTI ]. 3.) In contrast to sex, age affect the results of the urine dipstick test. 4.) This test has good result in adult particularly old age but, not in children.