Prevalence and molecular characterization of Shiga toxinproducingEscherichia coli in Sheep farms of Sanandaj-Iran

Background and Aim : Shiga toxin-producing Escherichia coli (STEC) strains have emerged asimportant foodborne pathogens of global public health concern, causing life-threatening diseases.Animal and their products have been documented as important reservoirs for STECs, especiallyE. coli O۱۵۷. The aim of this study was to investigate STECs from healthy and diarrheal sheep inSanandaj, Iran.Methods : In the current study, a total of ۸۱ samples taken from sheep feces (۲۲ samples fromdiarrheal sheep and ۵۹ samples from healthy sheep). E. coli and subsequently STEC strain wasdetected according to standard protocol (cultural characterization and PCR assays). Finally, thefrequency of Shiga-toxin producing gene(s) (stx۱, stx۲), intimin (eaeA) and enterohemolysin(hlyA) was detected among STEC isolates using duplex PCR.Results : Totally, ۴۲ E. coli were isolated from ۸۱ fecal samples (۵۱.۸۵% contamination). Ofthese, ۳۴ isolates (۸۰.۹%) were identified as STEC patotypes based on cultured on Sorbitol-MacConkey (SMAC) medium and also the presence of stx۱ and/or stx۲. Of these, only ۳ isolates(۷.۱%) were identified as serotype O۱۵۷:H۷ based on PCR assay. In addition, the results showedthat ۲۲.۷% of healthy samples and ۴۹.۲% of diarrheal samples had STEC bacteria. Overall, thePCR results showed that ۳۳ (۹۷%), ۱۲ (۳۵.۳%) and ۸ (۲۳.۵%), isolates carried stx۱, stx۲ and hlyA,respectively. The eaeA gene was not found in any isolatesConclusion : In conclusion, the present study revealed high prevalence rate of STEC bacteriaincluding serotype O۱۵۷:H۷ and non-O۱۵۷:H۷ among sheep feces which highlight the importanceof sheep as a reservoir of STEC pathogen in Sanandaj region. Therefore, the more control andpreventive measures must be done to control the contamination by this pathogen.

کلیدواژه ها:

Shiga toxin-producing Escherichia coli ، stx۱ ، stx۲ ، eaeA ، hlyA