Escherichia coli comes in many different forms — far too many, in fact, to list here. Most are completely harmless. E. coli occurs naturally in human beings and is known to aid our digestive system. The most dangerous strains, those that cause the well-known symptomatology (including bloody diarrhea and kidney failure) in humans, produce Shiga toxins. These are referred to as Enterohemorrhagic Escherichia Coli (EHECs).
