Enteropathogenic Escherichia coli

Escherichia coli (/ˌɛʃəˈrɪkiə ˈkoʊlɪ/ Anglicized to /ˌɛʃəˈrɪkiə ˈkoʊlaɪ/; commonly abbreviated E. coli) is a gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms (endotherms). Most E. coli strains are harmless, but pathogenic varieties cause serious food poisoning, septic shock, meningitis, or urinary tract infections in humans Unlike normal flora E. coli, the pathogenic varieties produce toxins and other virulence factors that enable them to reside in parts of the body normally not inhabited by E. coli and to damage host cells. These pathogenic traits are encoded by virulence genes carried only by the pathogens. E. coli and related bacteria constitute about 0.1% of gut flora, and fecal–oral transmission is the major route through which pathogenic strains of the bacterium cause disease. Cells are able to survive outside the body for a limited amount of time, which makes them ideal indicator organisms to test environmental samples for fecal contamination. The bacterium can also be grown easily and inexpensively in a laboratory setting, and has been intensively investigated for over 60 years. E. coli is the most widely studied prokaryotic model organism, and an important species in the fields of biotechnology and microbiology, where it has served as the host organism for the majority of work with recombinant DNA. German paediatrician and bacteriologist Theodor Escherich discovered E. coli in 1885, and it is now classified as part of the gamma-proteobacteria family Enterobacteriaceae. Pathogenic E. coli strains can be categorized based on elements that can elicit an immune response in animals, namely: For example, E. coli strain EDL933 is of the O157:H7 group. The outer membrane of an E. coli cell contains millions of lipopolysaccharide (LPS) molecules, which consists of: The O antigen is used for serotyping E. coli and these O group designations go from O1 to O181, with the exception of some groups which have been historically removed, namely O31, O47, O67, O72, O93 (now K84), O94, and O122; groups 174 to 181 are provisional (O174=OX3 and O175=OX7) or are under investigation (176 to 181 are STEC/VTEC). Additionally subtypes exist for many O groups (e.g. O128ab and O128ac).It should be noted though that antibodies towards several O antigens cross-react with other O antigens and partially to K antigens not only from E. coli, but also from other Escherichia species and Enterobacteriaceae species.