Spectrum of Diarrheagenic Escherichia coli in Drinking and Wastewater in Rafha City of Saudi Arabia

Introduction: E coli is one of the most important etiologic agent of diarrhea in children and adults. Based on the clinical features and virulence determinants, there are five major E. coli strains which cause diarrhea; Enterohemorrhagic E. coli (EHEC), Enteropathogenic E. coli (EPEC), Enterotoxigenic E. coli (ETEC), Enteroinvasive E. coli (EIEC) and Enteroaggregative E. coli (EAEC). The PCR based identification proves to be a better choice as it can differentiate between different strains on the basis of genetic difference.

Aim: The purpose of the current study was to isolate diarrheagenic E. coli from the drinking and wastewater from Rafha city of Saudi Arabia.

Methodology: One 100 drinking and wastewater samples (50 each) were included in the study. The samples were cultured on MacConkey agar plates at 37 oC for 24 hours. Pink colonies were carefully picked and subjected to DNA isolation and PCR detection and identification of E. coli and Diarrheagenic E. coli. The detected PCR products were sequenced for the confirmation.

Results: We identified 5 isolates out of 50 wastewater samples (10%) which were further categorized into 3 different DEC pathotypes. They included ETEC (2 out of 5), atypical EPEC (1 out of 5), and EAEC (1 out of 5); EIEC and EHEC were not detected.

Discussion and Conclusion: The prevalence of DEC strains is different across different studies which depends on different factors such as geographical location, number of samples taken, and the number and type of the target genes selected. The prevalence of DEC in the current study was much lower than other reported studies. Although the percentage of DEC strains in the wastewater samples from WWTP of Rafha was moderate to low, it can be a considerable risk factor for the people using ground water for drinking.