Abolfazl Rafati Zomorodi - Department of Bacteriology and Virology, Shiraz Medical School, Shiraz University of Medical Sciences, Shiraz, Iran
Gholamreza Hashemitabar - Department of Pathobiology, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran
Fatemeh Aflakian - Department of Pathobiology, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran.

Background and Aim : E. coli is a gram-negative, opportunistic bacterium commonly found inthe dairy cow's environment, infecting mammary glands through environmental contact. Shigatoxin-like producing E. coli is one of the significant E. coli pathotypes that causes severe diarrheaamong humans. Therefore, the distribution of E. coli isolates harboring the stx۱ and stx۲ genes infarm dairy is a highlighted concern for public health. The study aimed to evaluate virulence genes’prevalence, especially stx۱ and stx۲, among E. coli isolated from farm dairy.Methods : The current study collected ۴۷ E. coli isolates from clinical mastitis milk samples froma dairy farm in Mashhad. The biochemical standard tests were carried out to identify E. coliisolates. The multiplex Polymerase-chain reaction (m-PCR) assay was performed to assess theprevalence of four virulence genes, including stx۱, stx۲ eaeA, and hlyA genes among E. coliisolates.Results : The most frequent genes among all isolates, as determined by m-PCR, were eaeA ۴۲(۸۹.۳%) and stx۱ ۳۴ (۷۲.۳%). Also, the frequency of stx۲, hlyA, and sta genes in E. coli isolateswas found to be in ۲۶ (۵۵.۳%), ۹ (۱۹.۱%), and ۴ (۸.۵%), respectively.Conclusion : The high prevalence of stx۱ genes among isolates from farm dairy has indicatedfurther hygiene principle is essential in farm dairy to diminish the distribution of stx۱ genes amongisolates.

Bovine mastitis, E. coli, stx۱ gene