Comparative Diagnosis of Escherichia Coli-Induced Urinary Tract Infection Using Dipstick, Microbiological Culturing and PCR Methods in School-Going Adolescents

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Urinary tract infection (UTI) poses serious future clinical repercussions, such as hypertension, anaemia, kidney failure and death. Therefore, there is the need for the early detection and diagnosis of UTI. Currently, the use of the standard microbiological culture diagnostic method is hindered by the microbial tendency of being viable but non-culturable. On the other hand, direct Polymerase Chain Reaction (PCR) has proven to be more sensitive in detecting pathogens in various biological samples, although interference by specimen components and the possibility of contamination are some challenges. This work was thus aimed at the design of a simple and reliable PCR protocol for detecting uropathogens and comparing it with dipstick and culture, using Escherichia coli as the indicator uropathogen. This study, a cross-sectional one, involved the collection of urine samples from 272 adolescent students, aged between 13 and 18 years. The PCR protocol targeted a more specific pap C gene for fimbriae formation and the bacteriocin usp gene sequences for amplification. A general prevalence of 30.9% UTI was found. Using a sub-population made up of 195 subjects, for the comparative diagnosis of the three methods, the prevalence were 42.1%, 39.8% and 72.7% for dipstick, microbiological culturing and PCR respectively. PCR had a higher sensitivity of 71% and Receiver Operator Characteristic curve area of 0.7231± 0.0262, p< 0.0001, compared to the microbiological culture method. In addition, the ROC curve area for PCR was significantly higher than dipstick (0.7205± 0.0262, p< 0.0001) indicating PCR’s superiority as a diagnostic tool. On the other hand, there was no statistical difference between the microbiological culturing method and dipstick as diagnostic tools (0.5026± 0.02927, p= 0.9302). The leukocyte esterase parameter in the dipstick method was found to be more useful to the physician in making diagnosis with a positive predictive value of 52% and a negative predictive value of 76%. The usp gene was also found to be more significantly distributed in urine isolates than pap C with P value of 0.0020. This suggests that most of the strains of Escherichia coli implicated in UTI in the sample population employ more of bacteriocin production to compete with other microbes in the urinary tract than the production of adhesion structures. The PCR is therefore, a good complementary tool for diagnosis of UTI.
This Dissertation is Presented to the Department of Biochemistry and Biotechnology in partial fulfillment of the Requirements for the Award of an M.Sc. Degree in Biotechnology,