E. coli is the head of the large bacterial family, Enterobacteriaceae, the enteric bacteria, which are faculatively anaerobic Gram negative rods that live in the intestinal tracts of animals in health and disease. Pili are macromolecular structures that allow binding to a digalactoside receptor in the urinary tract. Escherichia coli are Gram negative bacterium that are commonly found in the lower intestine of warm-blooded organisms (endotherms). Their serological types are determined in combination with somatic antigens (O group: O1-O173) and flagella antigens (H type: H1-H56). The E. coli that cause intestinal infectious diseases including diarrhea, acute gastritis or colitis are referred to as pathogenic E. coli, which are classified into the following 4 groups according to differences in the mode of pathogenicity; enteropathogenic E. coli (EPEC), enteroinvasive E. coli (EIEC), enterotoxigenic E. coli (ETEC) and enterohemorrhagic E. coli (EHEC). Although the identification of pathogenic E. coli requires verification of their pathogenicity, pathogenic E. coli often have specific serotypes; therefore, typing of the serogroup and serotype is necessary in screening pathogenic E. coli.