Temporal Appraisal and Molecular Characterization of Escherichia coli from Oyun River, Kwara State, Nigeria

Introduction: Escherichia coli, an indicator of feacal contamination has been proven to be the cause of several disease outbreaks in countries and continents around the world.

Aim: To determine the genotypic variants of Escherichia coli present in Oyun River and provide information regarding the high-risk variants of E. coli in Oyun River.

Study Design: The study cuts across the two seasons of Nigeria’s tropical climate weather, being the peak of the Harmattan season and the onset of the Rainy season. Three sampling sites (Jimba Oja; Unilorin Dam and Oyun in Ilorin, Kwara State) along the River course were examined for three months (February – April).

Methodology: Heterotrophic counts, coli form counts and molecular characterization via PCR using 16 sRNA primers, of water samples were done using standard microbiological and molecular methods.

Results: Bacteriological results showed monthly mean values of microbial counts, ranged from 23.5 x 106 – 45.17 x 106 cfu/mL and total coli form count ranged from 53 cfu/100 mL to 256 cfu/100 mLs, both of which exceed the WHO standards of 100 cfu/mL for total microbial count and <1 cfu/100 mLs for total coliforms. A total of forty-eight coliforms were isolated, thirty two of which were Escherichia coli. Sequencing and BLAST analysis of eleven of the isolates using NCBI’s online database revealed five different strains. They include: Escherichia coli FAP1 genome (9.1%); Escherichia coli strain ST2747 (54.5%); Escherichia coli strain EADK4 (9.1%); Escherichia coli strain ST540 (18.2%) and Escherichia coli strain NCM3722 (9.1%). Correlation of results with previous studies showed that most of the strains identified were pathogenic. The E. coli strains isolated, coupled with the bacterial load, coliform count and some physicochemical parameters of Oyun River makes it unsafe for public consumption if not treated. Efforts therefore should be made to treat the water before use, while making frantic efforts to prevent further contamination of Oyun River.