Distribution of Escherichia coli Shiga toxin encoding genes (stx1, stx2) in Sangesari lambs suffering from diarrhea by Multiplex PCR technique

Shiga toxin-producing Escherichia coli (STEC) strains are human pathogens linked to hemorrhagic colitis and hemolytic uremic syndrome. Shiga toxins (Stx1 and Stx2) are the major virulent factors of these strains. The aim of this study was to investigate the prevalence and distribution of stx1 and stx2 gene in E. coli strains isolated from Sangesari lambs domesticated in Semnan suburb, Iran. During a 3-monthes survey in 2014, 160 samples of recto-anal mucosal swabs were collected from lambs with diarrhea. They were examined for the E. coli in cultural medium and biochemical tests as the causative agent of gastrointestinal tract (GI) infection and investigated the presence of stx1 and stx2 genes by using multiplex-PCR. Fifty one Escherichia coli strains were isolated from 160 fecal samples. Twelve of them were (24%) positive for at least one type of STX genes (STEC strain). Of the 12 STEC isolates, 5 (10%) harbored stx1, 4 (8%) stx2, and 3 (6%) carried both stx1 and stx2. The frequency of stx1 and stx2 distribution in Sangesari lambs and their relation to human GI diseases is not well understood yet. According to the popularity of lamb meat in Iran, specially breeding these animals in Semnan suburbs, it is warrant to consider precise regulations to restrict and prevent the prevalence of this life-threatening and foodborne diseases in Iran.