Escherichia coli (E. coli) are a group of bacteria, which are a natural part of the intestinal flora of warm-blooded animals, including humans. Most E. coli are non-pathogenic and are essential for the normal function of a healthy intestine . However, there are also pathogenic types of E. coli such as Shiga toxin-producing E. coli (STEC), also called Verocytotoxin-producing E. coli (VTEC). Their virulence is associated mainly with the production of two cytotoxins: stx1 and stx2., whose mode of action involves inhibition of protein synthesis in the target cell . Abdominal cramps, (bloody) diarrhoea, and sometimes fever and vomiting are the most common symptoms of STEC infection but in severe cases infection may lead to the development of haemolytic uremic syndrome (HUS) which is a life-threatening disease . Although the prevalence of STEC infections in The European Union is lower compared with Salmonella spp. and Campylobacter spp , it remains a high risk to public health due to its low infectious dose (1-100 CFU ), its ability for survival and transmission in the agri-food environment, and the high mortality rate (1.2 % for O157 and O104 serotypes and between 0.1%-0.2% for other serotypes )) compared to other food-borne pathogens . Ruminants, especially cattle are considered to be the most important reservoir of STEC and the infections occur from direct or indirect contamination in the agri-food chain .