E. coli bacterial culture (white) being grown in a petri dish on a nutrient medium (red). There are several different strains of E. coli (Escherichia coli) bacteria. Some strains are non-pathogenic and are found in human intestines. Other strains cause food poisoning with bloody diarrhoea. These strains can be ingested from contaminated beef and milk. Urogenital infections are also possible.