Escherichia coli is a Gram-negative cane (bacillus) of the Enterobacteriaceae family. Most E. coli are normal diners found in the digestive tract. The pathogenic strains of this organism are distinguished from normal flora by possessing virulence factors, such as exotoxins. Enterovasive E. coli invade the cells of the colon mucosa, extending from one cell to another in a similar way to the Shigella spp. Bacteria, but without toxin production. It manifests as an aqueous diarrhea or as a hemorrhagic diarrhea, it can also cause abdominal pain and fever. It is very common in underdeveloped countries.