Escherichia coli

Escherichia coli , common bacterium that normally inhabits the intestinal tracts of humans and animals, but can cause infection in other parts of the body, especially the urinary tract. It is the most common member of the genus Escherichia, named for Theodor Escherich, a German physician. E. coli is a Gram-negative, rod-shaped bacterium propelled by long, rapidly rotating flagella. It is part of the normal flora of the mouth and gut and helps protect the intestinal tract from bacterial infection, aids in digestion, and produces small amounts of vitamins B ₁₂ and K. The bacterium, which is also found in soil and water, is widely used in laboratory research and is said to be the most thoroughly studied life form. In genetic engineering it is the microorganism preferred for use as a host for the gene-splicing techniques used to clone genes.

E. Coli Food Poisoning

In 1982 a particularly toxic strain of E. coli, E. coli 0157:H7, was identified; it produces a toxin that damages cells that line the intestines. Usually transmitted via raw or undercooked ground meat (thought to become contaminated during slaughter or processing), the strain can potentially contaminate any food and can also be spread by infected persons. Symptoms, which begin 1 to 8 days after infection and last for about a week, include bloody diarrhea, abdominal pain, vomiting, and in some cases, fever. The most serious complication is a hemolytic-uremic syndrome that can lead to kidney failure and death, especially in children. There is no treatment other than supportive care. Practical preventive measures include thorough cooking of meat and careful hygiene around infected individuals.

In 1993, E. coli 0157:H7 was responsible for an outbreak of food poisoning in Washington state that sickened 500 people, killing three. A rapid rise in the number of cases of illness caused by the strain has prompted calls for a reevaluation of food inspection techniques in the United States. Irradiation of meat and some greens is now approved by the FDA as a means to destroy such bacteria.

Escherichia coli (E. coli) A species of Gram-negative aerobic bacteria that is found in the intestine (see coliform bacteria) and is also widely used in microbiological and genetics research. The motile rod-shaped cells ferment lactose and are usually harmless commensals, although certain strains are pathogenic and can cause a severe form of food poisoning. Studies of E. coli laboratory cultures have revealed much about the genetics of prokaryotes; the species is also frequently used in genetic engineering, particularly as a host for gene cloning and the expression of recombinant foreign genes in culture.

Escherichia (family Enterobacteriaceae) A genus of Gram-negative, rod-shaped bacteria. E. coli is the most thoroughly studied of all bacteria. It is found mostly in the lower gut of mammals, but also occurs in, e.g., sewage-contaminated natural waters; it is commonly used as an indicator of sewage pollution. Some strains of E. coli are pathogenic, causing, for example, dysentery in the old and in infants and young animals.