Felis ISSN 2398-2950
Escherichia coli
Synonym(s): E. coli
Contributor(s): Richard Walker
Introduction
Classification
Taxonomy
- Family: Enterobacteriaceae.
- Genus: Escherichia.
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.
- Attaching and effacing E. coli (AEEC): 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.
This article is available in full to registered subscribers
Sign up now to purchase a 30 day trial, or
Login
Clinical Effects
Epidemiology
Habitat
- Pathogenic and non-pathogenic strains of E. coli inhibit the lower gastrointestinal tract.
- Also abundant in the environment of animals.
Lifecycle
- Reproduces by binary fission, usually in the gastrointestinal tract of the host.
- Conjugation may occur with other bacteria to allow exchange of plasmids, which may bear toxin genes, and other transposable elements.
Transmission
Pathological effects
Predisposers
- Insufficient passive (colostral) immunity, ie neonates.
- Poor environmental hygiene → build-up of pathogenic strain → may overcome normal levels of passive immunity.
- Intensive farming methods → rapid transmission of pathogenic strains.
- Age - (less than 1 week old) because:
- Normal flora not yet established.
- Immature immune system.
- Receptors for the adhesins of E. coli only present for first week of life (calves) and first 6 weeks of life (piglets).
- Stress factors, eg changed environment and diet in recently weaned pigs.
- Heavy grain diets - allowing massive colonization of enterotoxigenic, K88 and K99 strains ofE. coli.
- Recent change in feed and period of rapid growth, eg edema disease in pigs.
Virulence factors of pathogenic E. coli strains
- Capsular polysaccharide (K antigen).
- Endotoxin (Lipid A) associated with septicemia and the toxemia of coliform mastitis.
- Certain fimbriae are protein adhesins.
- Alpha and beta hemolysins.
- Siderophores.
- Heat-labile and heat-stable enterotoxins (LT enterotoxin is antigenically related to the cholera toxin).
- Verotoxin or Shiga-like toxins - inhibit protein synthesis in host cells. Important in edema disease and in neonatal calves and piglets.
Opportunistic infections
- E. coli strains, normally regarded as non-pathogenic can cause opportunistic infections, eg mastitis and metritis.
Other Host Effects
- Predominant facultative species in large intestine.
Diseases associated with E. coli
Dog and cat
- Neonatal colisepticemia.
- Pyometra Pyometra.
- Urinary tract infection.
Pig
- Neonatal diarrhea.
- Colisepticemia.
- Piglet meningitis.
- Edema disease.
- Coliform mastitis.
- Mastitis-metritis-agalactia (MMA) syndrome.
Cattle
- White scour.
- Colisepticemia.
- Joint ill.
- Coliform mastitis.
Sheep
- Colibacillosis and colisepticemia.
- 'Watery mouth'.
- Coliform mastitis.
Poultry
- Omphalitis.
- Colisepticemia.
- Coligranuloma.
Other species
- Colibacillosis and colisepticemia.
Control
Control via animal
- Sound husbandry - the dam should be exposed to the local strains before parturition.
- Some vaccines are available.
- Maternal exposure to E. coli, either natural or artificial, allows for antibodies to be produced by the dam and secreted into the colostrum and milk.
- Commercially produced preparations containing monoclonal antibodies to adhesins can be given orally to the neonate.
Control via chemotherapies
- Most E. colis trains are sensitive to a wide range of antibiotics but resistance, often plasmid-mediated is frequently encountered.
- The use of antimicrobials to treat the diarrhea is controversial.
Vaccination
Diagnosis
This article is available in full to registered subscribers
Sign up now to purchase a 30 day trial, or
Login
Further Reading
Publications
Refereed papers
- Recent references from VetMed Resource and PubMed.
- Cullor J S (1995) Escherichia coli O157-H7 - the silent danger. Vet Med 90(1), 74-82.
- Dorn C R (1995) Escherichia coli O157-H7. JAVMA 206(10), 1995.
- Whipp S C, Rasmussen M A & Cray W C (1994) Animals as a source of Escherichia coli pathogenic for human beings. JAVMA 204(4), 1168-1175.
- Levine M (1987) Escherichia coli that causes diarrhoea - enterotoxigenic, enteropathogenic, enteroinvasive, enterohaemorrhagic and anteroadherent. J Infect Dis155, 377.