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 Enterovirulent Escherichia coli |
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Enterovirulent E. coli (EEC) strains include several major subgroups:
- Enterohemorrhagic E. coli (EHEC) causes hemorrhagic colitis and hemolytic uremic syndrome. Six verotoxins have been identified within this group, but only stx-1 and stx-2 seem to be important in human infections. E. coli O157:H7 is the principle serotype of this group.
- Enteroinvasive E. coli (EIEC) causes a diarrheal illness similar to shigellosis.
- Enterotoxigenic E. coli (ETEC) is a major cause of traveler's diarrhea and infant diarrhea in developing countries. These strains product a heat-labile toxin (LT) and/or a heat-stable toxin (ST).
- Enteropathogenic E. coli (EPEC) is an important cause of infant diarrhea.
- Enteroadherent E. coli (EAEC) is a newly added category and not fully characterized.
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Light microscope image of E. coli
From Picture book to the microbiology (2005), Institute of Microbiology, Seoul National University. |
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| [Other image link] : Scanning electron micrograph of Escherichia coli (Wikipedia) |
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Enterovirulent Escherichia coli infection
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How is E. coli O157:H7 spread?
The organism can be found on a small number of cattle farms and can live in the intestines of healthy cattle. Meat can become contaminated during slaughter, and organisms can be thoroughly mixed into beef when it is ground. Bacteria present on the cow's udders or on equipment may get into raw milk.
Eating meat, especially ground beef, that has not been cooked sufficiently to kill E. coli O157:H7 can cause infection. Contaminated meat looks and smells normal. Although the number of organisms required to cause disease isn't known, it is suspected to be very small.
Among other known sources of infection are consumption of sprouts, lettuce, salami, unpasteurized milk and juice, and swimming in or drinking sewage-contaminated water.
Bacteria in diarrheal stools of infected persons can be passed from one person to another if hygiene or handwashing habits are inadequate. This is particularly likely among toddlers who are not toilet trained. Family members and playmates of these children are at high risk of becoming infected.
Young children typically shed the organism in their feces for a week or two after their illness resolves. Older children rarely carry the organism without symptoms.
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1: SeafoodNIC, UC, U.S.A. - Coliforms, Fecal Coliforms and Escherichia coli
2: Wikipedia - Escherichia coli
3: Escherichia Coli 0157: H7 and Other Shiga Toxin-Producing E. Coli Strains. James B. Kaper, Alison D. O'Brien, Alison D. O'Brien. Amer Society for Microbiology (ASM).
4: EBI > 2Can > Karyn's Genomes > Escherichia coli |
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