Escherichia coli (E. coli) is a bacterium.
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. The Enterobacteriaceae are among the most important bacteria medically. A number of genera within the family are human intestinal pathogens (e.g. Salmonella, Shigella, Yersinia). Several others are normal colonists of the human gastrointestinal tract (e.g. Escherichia, Enterobacter, Klebsiella), but these bacteria, as well, may occasionally be associated with diseases of humans.
In humans the bacterium, which can be transmitted by foods, animal contact, and drinking water, can cause bloody diarrhea, and also lead to hemolytic uremic syndrome (HUS), a life threatening disease. Although other generic strains of E. coli are thought to be harmless to humans, the O157:H7 strain is particularly virulent and dangerous. USDA began an E. coli O157:H7 testing plan in 1994. As part of the Hazard Analysis and Critical Control Point (HACCP) rule,all meat and poultry slaughter plants are required to test carcasses regularly for generic E. coli in order to verify that their sanitary systems are effectively controlling fecal contamination. E. coli has been described as the workhorse of molecular biology. It is routinely used in laboratories as a tool for the manipulation of DNA and for producing proteins, as well as being a model organism for the study of cellular processes.