Escherichia coli (ĕsh´ərĬk´ēə kō´lī), 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 B12 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 (Shiga toxin) that damages cells that line the intestines. The same strain was responsible for a 1993 outbreak of food poisoning in Washington state, which sickened 500 people and killed three, and a series of outbreaks in 1996 in Japan, which sickened some 10,000 and killed 12. A rarer and more virulent Shiga-toxin-producing strain, E. coli O104:H4, was the cause of the 2011 outbreak centered on N Germany that sickened more than 4,000 people from more than a dozen countries and killed 50.
Food-poisoning outbreaks due to Shiga-toxin-producing E. coli (STEC) are typically the result of transmission via raw or undercooked ground meat (thought to become contaminated during slaughter or processing) or contaminated salad ingredients. The strains can potentially contaminate any food. STEC infections can also occur through other means, such as contact with infected persons or cattle, or consumption of or contact with contaminated water.
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 (HUS) that can lead to kidney failure and death, especially in children. The 2011 infection, for example, led to HUS in some 900 people. There is no treatment other than supportive care. Practical preventive measures include thorough cooking of meat and careful hygiene around infected individuals.
A rapid rise in the number of cases of illness caused by STEC strains 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.