Escherichia coli
From DrugPedia: A Wikipedia for Drug discovery
Escherichia coli
It is Gram-negative, facultative anaerobic and non-sporulating. Cells are typically rod-shaped and are about 2 micrometres (μm) long and 0.5 μm in diameter, with a cell volume of 0.6 - 0.7 μm3. It can live on a wide variety of substrates. E. coli uses mixed-acid fermentation in anaerobic conditions, producing lactate, succinate, ethanol, acetate and carbon dioxide.
| Domain | Bacteria |
|---|---|
| Phylum | Proteobacteria |
| Class | Gamma Proteobacteria |
| Order | Coccidioides |
| Family | Enterobacteriaceae |
| Genus | Escherichia |
| Species | E. coli |
| Binomial | Escherichia coli |
Contents |
Surface Characteristics
The bacterial capsular polysacchirides K5 is disaccharide with repeating unit 4-β-GlcUA(1-->4)-α-GlcNAc.
Pathogenic Activity
Virulent strains of E. coli can cause gastroenteritis, urinary tract infections, and neonatal meningitis. In rarer cases, virulent strains are also responsible for hæmolytic-uremic syndrome (HUS), peritonitis, mastitis, septicemia and Gram-negative pneumonia.
Virulence
- Enterotoxigenic E. coli (ETEC) uses fimbrial adhesins (projections from the bacterial cell surface) to bind enterocyte cells in the small intestine. ETEC can produce two proteinaceous enterotoxins:
1. larger of the two proteins, LT enterotoxin, is similar to cholera toxin in structure and function.
2. smaller protein, ST enterotoxin causes cGMP accumulation in the target cells and a subsequent secretion of fluid and electrolytes into the intestinal lumen.
ETEC strains are non-invasive, and they do not leave the intestinal lumen. ETEC is the leading bacterial cause of diarrhea in children in the developing world, as well as the most common cause of traveler's diarrhea. Each year, ETEC causes more than 200 million cases of diarrhea and 380,000 deaths, mostly in children in developing countries.
- Enteroinvasive E. coli (EIEC) infection causes a syndrome that is identical to Shigellosis, with profuse diarrhea and high fever.
- Enteroaggregative E. coli (EAEC), so named because they have fimbriae which aggregate tissue culture cells, EAEC bind to the intestinal mucosa to cause watery diarrhea without fever. EAEC are non-invasive. They produce a hemolysin and an ST enterotoxin similar to that of ETEC.
