Clinical Evaluation of Pyuria, Bacteriuria and Culture for Diagnosis of Urinary Tract Infection

Background: Culture remains the gold standard for the diagnosis of urinary tract infections (UTIs). However, the diagnosis of UTIs can be potentially enhanced when clinical characteristics of UTI, pyuria and bacteriuria are considered. Methodology: To evaluate the relationship between pyuria, bacteriuria and clinical characteristics with culture, un-centrifuged urine samples (N=817) were subjected to direct wet mount, direct Gram staining and semi-quantitative culture and the results were compared. Results: The direct wet mount and direct gram staining showed an overall sensitivity, specificity, positive predictive value and negative predictive value of 11.08%, 88.88%, 87.96%, 29.28% and 34.21%, 96.55%, 91% and 38.89%, respectively, as compared to semi-quantitative culture. Alternatively, the overall sensitivity, specificity, positive predictive value and negative predictive value of clinical characteristics of both upper and lower UTIs (most sensitive and specific symptoms combined) were found to be 55.14%, 76.06%, 71.29%, 31.47%, respectively. Conclusion: Both the direct wet mount and direct Gram staining could be considered as screening tests for diagnosis of UTI due to its low sensitivity and high specificity. However, integrated approaches wherein clinical characteristics of UTI combined with culture results would be of high diagnostic value in the diagnosis of UTI.