Survey on O157:H7 enterohemorrhagic Escherichia coli (EHEC) in cattle in Golestan province, Iran

Background and Objectives: A diverse group of Escherichia coli are known as enterohemorrhagic Escherichia coli (EHEC) including O157:H7 and non-O157 EHEC. Enterohemorrhagic strains are related to severe clinical conditions in humans including hemorrhagic colitis and hemolytic uremic syndrome, and most of the recorded outbreaks occurred due to O157: H7 E. coli. The aim of the present study was to investigate the presence of O157:H7 E. coli among healthy cattle in Golestan province. Materials and Methods: Fecal samples were collected from 180 clinically healthy cattle in Golestan province. After primary enrichment, samples were streaked on sorbitol MacConkey agar supplemented with cefixime and potassium tellurite (CT-SMAC). Non-sorbitol fermenting (NSF) Escherichia coli isolates were subjected to serotyping using commercial O157 antisera and rfb O157 gene PCR. Isolates were additionally tested for major virulence factors of EHEC including stx1, stx2, eae and ehly by multiplex-PCR. Results: Eighteen NSF isolates were recovered from CT-SMAC confirmed as E. coli in biochemical tests. None of the obtained isolates belonged to O157 serogroup. Overall, two isolates harbored the tested virulence genes; one isolate possessed stx2 and ehly, and the other one carried stx2, eae and ehly. Conclusion: The results of this study indicated that cattle in Golestan province could be the reservoir for non-O157 EHEC.