Comparative Study on Diagnosis of Urinary Tract Infection among Adolescents in the Kumasi Metropolis Using Dipstick, Culture and PCR Methods

Abstract

Urinary tract infection (UTI) is associated with clinical conditions such as hypertension, anaemia, kidney failure and even death. Diagnosis and early detection of UTI are critical measures in the management of the disease. The classical microbiological culture method is hindered by long diagnostic time and characteristic features of certain microbes becoming viable-but-non-culturable (VBNC). Direct PCR is a more sensitive and rapid diagnostic tool for detecting pathogens in clini-cal samples. This work aimed at developing a simplified PCR assay for detection of uropathogenic Escherichia coli, an index microorganism for UTI and the results compared to two common diagnostic markers – i.e., dipstick and microbiological culture methods. The cross-sectional study involved collection of urine samples from 195 adolescents, aged between 13 and 18 years. DNA segments were amplified using specific primers targeting papC gene for fimbriae formation and the bacteriocin usp gene of the uropathogenic E. coli. Comparing the three diagnostic tools, the PCR produced the highest sensitivity of 71%, and the nitrite-based dipstick method recording the least sensitivity of 3%. Leukocyte esterase-based dipstick recorded the highest specificity of 76% as against 24% specificity by the PCR method. In addition, leukocyte esterase detection dipstick pro-duced the highest values for both positive and negative predictive values of 52% and 76%, respec-tively. From the receiver operator characteristic (ROC) analyses, PCR showed an area of 0.7231± 0.0262 (age in years X number of positives) over culture method with P value 0.0001, compared to 0.7205± 0.02623 (age in years X number of positives) of culture method over the dipstick method (p< 0.0001). Although the PCR diagnostic method for UTI uropathogenic indicator (E. coli) was found to be superior method as compared to culture and dipstick methods, it should be made a complementary UTI diagnostic tool due to the low specificity.

Keywords: Dipstick; Escherichia coli; PCR; papC gene; urinary tract infection (UTI); usp gene.