Enterotoxigenic Escherichia coli
|Enterotoxigenic Escherichia coli|
|Classification and external resources|
Enterotoxigenic Escherichia coli (ETEC) is a type of Escherichia coli and the leading bacterial cause of diarrhea in the developing world, as well as the most common cause of travelers' diarrhea. Insufficient data exist, but conservative estimates suggest that each year, approximately 210 million cases and 380,000 deaths occur, mostly in children, from ETEC. A number of pathogenic isolates are termed ETEC, but the main hallmarks of this type of bacteria are expression of one or more enterotoxins and presence of fimbriae used for attachment to host intestinal cells.
- Enterotoxins 1
- Presentation 2
- Prevention and treatment 3
- See also 4
- References 5
- External links 6
Some strains of ETEC produce a heat-labile exotoxin (LT) that is under the genetic control of a plasmid. The strain also triggers fimbrial adhesion that extends from the surface of the E. coli cell and has a B subunit that attaches to the GM1 ganglioside at the brush border of the small intestine epithelium cell and stimulates the entry of the A subunit into the cell, where the latter activates adenylyl cyclase. This increases the amount of cAMP, and results in intense and prolonged hypersecretion of chlorides and water; while also inhibiting the reabsorption of sodium. The gut lumen contains large amount of fluid, and motility, leading to diarrhea that can last for several days. LT is an antigen that can cross-react with the enterotoxin to stimulate the production of neutralizing immunoglobulin antibodies in the serum of previously infected people with enterotoxigenic E coli. People that reside in locations that have high prevalence of this strain are likely to possess antibodies to said strain and are less prone to presenting with diarrhea if re-exposed to the strain.  Some strains of ETEC produce another toxin called heat-stable enterotoxin (ST) which are regulated by a heterogeneous group of plasmids. ST activates guanylyl cyclase in the signal pathway of the enteric epithelial cells and triggers fluid secretion. Also, some ST E. coli strains are capable of making LT; the strain that contains both ST and LT toxins produces a more severe diarrhea. The plasmids carrying the genes for enterotoxins may also encode genes used for the colonization factors that initiate the attachment of E. coli strains to the intestinal epithelium.
Mnemonic: Labile like the Air (cAMP), Stable like the Ground(cGMP).
Infection with ETEC can cause profuse watery diarrhea with no blood nor leukocytes and abdominal cramping. Fever, nausea with or without vomiting, chills, loss of appetite, headache, muscle aches and bloating can also occur but are less common.
Prevention and treatment
There are currently available treatment options against
- Escherichia coliCenters for Disease Control and Prevention: Enterotoxigenic
- (ETEC)Escherichia coliVaccine Resource Library: Shigellosis and enterotoxigenic
- Escherichia coliWorld Health Organization: Enterotoxigenic
- (ETEC).Escherichia coliWorld Health Organization. Enterotoxigenic
- Gupta, SK; Keck J; Ram PK; et al. (2008). "Analysis of Data Gaps Pertaining to Enterotoxigenic Escherichia coli Infections in Low and Medium Human Development Index Countries, 1984-2005". Epidemiology and Infection 136 (6): 721–738.
- (ETEC).escherichia coliWorld Health Organization. Institute for Vaccine Research. Enterotoxigenic
- Qadri, F.; Svennerholm, A. M.; Faruque, A. S. G.; Bradley Sack, R. (2005). in Developing Countries: Epidemiology, Microbiology, Clinical Features, Treatment, and Prevention"Escherichia coli"Enterotoxigenic . Clinical Microbiology Reviews 18 (3): 465–483.
- (ETEC)Escherichia coliUS Centers for Disease Control and Prevention. Enterotoxigenic
- World Health Organization. "nterotoxigenic Escherichia coli (ETEC)". Retrieved 2 May 2012.
- Girard, M.; Steele, D.; Chaignat, C. L.; Kieny, M. P. (2006). "A review of vaccine research and development: human enteric infections". Vaccine 24 (15): 2732–2750.
- PATH, bvgh (March 2011). "The Case for Investment in Enterotoxigenic Escherichia coli Vaccines" (PDF). Retrieved 2 May 2012.
Treatment for ETEC infection includes rehydration therapy and antibiotics, although ETEC is frequently resistant to common antibiotics. Improved sanitation is also key, since the transmission of this bacterium is fecal contamination of food and water supplies, one way to prevent infection is by improving public and private health facilities. Another simple prevention of infection is by drinking factory bottled water, this is especially important for travelers and traveling military.