Escherichia coli (E. coli) is a germ that occurs naturally in the gut of mammals and birds, as well as in the human intestinal flora. However, certain E. coli types can cause severe diarrhea in humans. These virulent E. coli types include Shiga toxin-producing E. coli (STEC), also known as Verotoxin-producing E. coli (VTEC).
Their damaging effect is due to the fact that STEC produce toxins known as Shiga toxins (Stx), which can cause disease in the human gut. As the best known STEC representative, an enterohaemorrhagic E. coli (EHEC) strain of the serotype O104:H4 was responsible for numerous severe cases of haemolyticuremic syndrome (HUS) and bloody diarrhea in Germany in 2011, as a result of which 53 people died.