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. Enterohemorrhagic Escherichia coli (ECEH) is a set of pathogenic E. coli, which can cause diarrhea or hemorrhagic colitis in humans. They produce verotoxin, can adhere to the epithelial cells of the intestine wall and are common in developed countries.