Shiga toxin-producing E. coli (STEC) is a type of pathogenic E. coli strain capable of producing Shiga toxins. The strains are also known as verotoxin- or verocytotoxin-producing E. coli (VTEC). Virulent strains among this pathotype are also called enterohaemorrhagic E. coli (EHEC) and can cause illness ranging from mild intestinal disease to severe kidney complications. There are around 250 different E. coli O serotypes producing Shiga toxin, of which over 100 have been associated with human disease. While the serotype O157:H7 is considered as clinically the most important, up to 50% of STEC infections are caused by non-O157 serotypes.