Evaluation of the prevalence of enterotoxigenic and enteropathogenic Escherichia coli in raw milk and dairy products by Duplex-PCR

Enterotoxigenic Escherichia coli is very important and usual, particularly in the developing countries and it is the main reason of diarrhea in travelers to developing countries. Enteropathogenic Escherichia coli strains are defined as intimin-containing diarrheagenic E. coli but do not produce Shiga toxin, which can cause diarrhea in humans and different animal species. Pathogenic Escherichia coli strains are commonly transmitted through contaminated food and water. The aim of this study was to identify Escherichia coli pathotypes in raw milk and dairy product samples using Duplex PCR. A total of 102 raw milk and dairy products samples were randomly collected from different localities in Western Azerbaijan and transferred in sterile conditions to department of food and drug microbiology lab, affiliated to Tabriz University of medical sciences. 46 E. coli were identified based on culture and a number of biochemical tests. Duplex PCR assay were developed for detection of enterotoxigenic and enteropathogenic Escherichia coli. The target genes selected for each category were the lt and st for ETEC, eae and bfp for EPEC isolates. According to the results, the rate of E. coli in samples was 45%. No ETEC strains were isolated from any of the samples examined and only 2 (4.34%) EPEC strains were identified. Previous studies and our results showed the high percentage of E. coli and EPEC in raw milk products. It was concluded that using raw milk without pasteurization, and using traditional dairy products produced in unsanitary conditions and are the main resources for growth of E. coli pathotypes.