Enterovirulent E. Coli (EEC) (cont.)

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How do enterovirulent E. coli groups cause disease?

In general, all EEC groups cause disease by disruption of the normal secretory mechanisms of the intestines which leads to diarrhea. As outlined previously, different groups use different methods that ultimately results in diarrhea; the type of diarrhea and the intensity of the disease are related to the mechanisms used by the bacteria.

  • EHEC secrete Shiga toxins that can not only destroy intestinal cells, but can be spread to other organ systems to cause additional disease. E. coli 0157:H7 is the major EHEC pathogen responsible and is considered to be one of the most virulent organisms in all of the EEC groups because of Shiga toxin production.
  • EPEC group organisms also can produce a toxin closely related to Shigella toxin that has many of the same properties of Shiga toxin although the serotypes cause the disease (sometimes milder) mainly in children.
  • The ETEC group does not produce Shiga toxins or their closely related toxins, but ETEC do produce two other exotoxins that stimulate the intestines to secrete fluid and mucus.
  • EIEC organisms, these bacteria have the ability to penetrate the epithelial cells that line areas of the human intestines. EIEC organisms then cause many of the cells to lyse thus disrupting the fluid adsorption and secretion capacity of the intestines.
  • Both EAEC and EAggEC groups of bacteria, by attaching to intestinal cells, cause irritation or inflammation of the intestinal cells. This physiologic and immunologic response also disrupts adsorption and secretion in the intestines.

When should one seek medical care for enterovirulent E. coli infection?

Many people (the large majority) do not need to seek medical care as most of the infections are self-limiting, unless the affected individual is immunodepressed or is an undernourished child in a third world country. Because a number of patients are children; their progress in self-limiting the disease needs to be carefully watched as they can, in some instances, rapidly deteriorate. This is the situation for all the EEC groups. Most infected individuals, unless diagnosed, will not even know they are infected with EEC since many bacterial and viral diseases have similar symptoms of nausea, low-grade fever, and diarrhea.

Many health care professionals suggest that affected individuals should seek medical care if:

  • there are signs of dehydration (for example, decreased urination, dry mucous membranes), especially in children under 5 years of age and the elderly;
  • sustained fever over 101 F (37.7 C);
  • presence of blood in the stool;
  • known ingestion of E. coli 0157:H7 or contaminated food or fluid or close personal contact with individuals known to have any E. coli infection caused by a EEC group bacteria; and/or
  • any complication of an E. coli EEC group infection (see complication section below).
Medically Reviewed by a Doctor on 4/28/2014

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