Escherichia coli

Classification

Taxonomy

• Family: Enterobacteriaceae.
• Genus: Escherichia.
• Species: coli.

Classification of enteritis-causing E. coli

• Strains:
  • Enterotoxigenic E. coli (ETEC): have fimbrial adhesins, produce enterotoxin, cause neonatal colibacillosis.
  • Enteropathogenic E. coli (EPEC): do not produce enterotoxins or Shiga-like toxins, cause enteritis/diarrhea and colisepticemia by other mechanisms.
  • Enteroinvasive E. coli (EIEC): invade intestinal mucosa, release endotoxins, cause colisepticemia.
  • Enterohemorrhagic E. coli (EHEC): colonize small intestine, attach to target cells and kill them, Shiga-like toxins, isolated from calves and rabbits with enteric disease.

Etymology

• Escherichia: named after Theodor Escherich, who named the type species of the genus.
• Greek: kolon - food, meat.

Distribution

• Worldwide.

Significance

• The major facultative gram-negative species comprising the normal flora of the gastrointestinal tract. Usually present in larger numbers in carnivores and omnivores than in herbivores.
• Presence in water supply usually indicates fecal contamination. Hence tests for its presence are widely used in water testing.
• Causes (or associated with as an opportunistic infection), a wide range of diseases in many species.