Description: Escherichia coli (E. coli) are Gram negative, non-sporulating bacteria, which belong to the normal intestinal flora of humans and animals. Shiga toxin-producing E. coli (STEC) are a group of E. coli that is defined by the capacity to produce toxins called Shiga toxins (Stx). Following ingestion of STEC, the significant risk of two serious and potentially life-threatening complications of infection, hemorrhagic colitis and hemolytic uremic syndrome (HUS), makes STEC food poisoning a serious public health problem. Besides Stx, human pathogenic STEC harbor additional virulence factors that are important for their pathogenicity. Although human infection may also be acquired by direct transmission from person to person or by direct contact of humans with animal carriers, the majority of STEC infections are food-borne in origin. The gastrointestinal tract of healthy ruminants seems to be the foremost important reservoir for STEC and ingestion of undercooked beef one of the most likely routes of transmission to humans. Other important food sources include faecally contaminated vegetables and drinking water