ISSN 2398-2969      

Escherichia coli

Clapis

Synonym(s): E. coli


Introduction

Classification

Taxonomy

  • Kingdom: Eubacteria.
  • Phylum: Proteobacteria.
  • Class: Gammaproteobacteria.
  • Order: Enterobacteriales.
  • Family: Enterobacteriaceae.
  • Genus:Escherichia.
  • Species:coli.

Classification of enteritis-causingE. colistrains

  • Pathogenic E. coli strains are characterized into pathotypes based on virulence properties and serological characteristics:
    • EnterotoxigenicE. coli(ETEC):
      • Have fimbriae which they use to bind to enterocytes.
      • Produce two proteinaceous enterotoxins.
      • Non-invasive.
      • Do not leave the intestinal lumen.
      • Leading cause of diarrhea in children in the developing world.
      • Common cause of Travelers' diarrhea. 
    • EnteropathogenicE. coli(EPEC):
      • Lack fimbriae.
      • Does not produce enterotoxins.
      • Causes enteritis/diarrhea.
      • Uses an adhesin (intimin). 
      • Moderately invasive.
      • Elicits an inflammatory response.
      • Attaches to enteric epithelial cells and induces the effacement of microvilli (aka attaching and effacingE. coli).
      • Most common pathotype seen in rabbits.
      • Can be a cause of economic loss for the commercial rabbit industry due to diarrhea and mortality.
    • Shiga toxin producingE. coli(STEC):
      • Also referred to as verocytotoxin-producingE. coli(VTEC) or enterohemorrhagicE. coli(EHEC).
      • This pathotype is the one most commonly heard about in the news in association with foodborne outbreaks.
      • Has fimbriae.
      • Shiga-like toxin.
      • Moderately invasive.
      • Attaches to enteric epithelial cells and induces the effacement of microvilli (aka attaching and effacingE. coli).
    • EnteroaggregativeE. coli(EAEC):
      • Have fimbriae.
      • Non-invasive.
      • Produce hemolysin and enterotoxin.
    • EnteroinvasiveE. coli(EIEC) and diffusely adherentE. coli(DAEC):
      • Found only in humans.

Etymology

  • Was originally namedBacterium coli commune.
  • Escherichia:named after Theodor Escherich (1857-1911) in 1919 who discoveredE. coliand its properties.
  • Latin:coli - colon.

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Clinical Effects

Epidemiology

Habitat

  • Pathogenic and non-pathogenic strains ofE. coliinhabit the lower gastrointestinal tract of many animals.
  • Not commonly found in rabbit intestines (or found in low numbers).
  • Abundant in the environment.

Lifecycle

  • Reproduces by binary fission.
  • Uses bacterial conjugation, transduction or transformation to transfer DNA: allows a horizontal spread of genetic material through a population. 
  • Conjugation may occur with other bacteria to allow exchange of plasmids, which may bear toxin genes, and other transposable element such as anti-bacterial resistance.

Transmission

  • Fecal-oral route.

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 (>1 week old) because:
    • Normal flora not yet established.
    • Immature immune system.
  • Stress factors, eg changed environment, weaning, transport, overcrowding, poor diet   diseases of the growing rabbit  .

Virulence factors of pathogenicE. colistrains

  • O antigen: part of the lipopolysaccharide (LPS) layer:
    • O antigen.
    • Core region.
    • Lipid A - associated with septicemia and toxemia.
  • K antigen: capsular polysaccharide.
  • H antigen: flagellin.
  • Certain fimbriae are protein adhesins.
  • Alpha and beta hemolysins.
  • Siderophores.
  • Heat-labile and heat-stable enterotoxins:
    • LT enterotoxin is related to the cholera toxin in structure and function.
    • ST enterotoxin causes a secretion of fluid and electrolytes into the intestinal lumen. 
  • Verotoxin or Shiga-like toxins - inhibit protein synthesis in host cells.
  • Villous atrophy and malabsorption occurs as a result of the attachment and effacing EPEC which causes diarrhea and subsequent death.

Opportunistic infections

  • E. colistrains, normally regarded as non-pathogenic can cause opportunistic infections.

Other Host Effects

diseases associated withE. coli

Control

Control via animal

  • Determine if you have normal colibacillosis   Colibacillosis   vs post-weaning colibacillosis:
    • Neonatal colibacillosis:
      • Commonly occurs between 1-14 days of age.
      • Watery diarrhea (stains perineum and abdomen yellow).
      • Possible to have 100% morbidity and mortality.
      • Subsequent litters of the doe may have passive immunity.
    • Post-weaning colibacillosis:
      • 4-6 week old rabbits.
      • Possible to have 50%+ mortality.
      • Rabbits that recover may not grow to full potential.
  • Death occurs in 5-14 days.
  • Disease process is limited to the cecum and colon.
  • Culture and sensitivity.
  • Antibiotic administration   Therapeutics: antimicrobials  .
  • Supportive and fluid therapy   Fluid therapy  .
  • Appropriate diet   Nutrition: dietary requirements  .
  • Appropriate husbandry and management.

Disease outbreaks ofE. colihave not been reported in pet rabbits.

Control via chemotherapies

  • MostE. colistrains are sensitive to a wide range of antibiotics but resistance, often plasmid-mediated is frequently encountered.
  • Treat individual rabbits based on the results of culture and sensitivity   Therapeutics: antimicrobials  .
  • Can use trimethoprim-sulfamethoxazole   Trimethoprim / sulfadiazine  30 mg/kg PO BID or enrofloxacin   Enrofloxacin  10 mg/kg PO BID, until the culture and sensitivity results are acquired.

Control via environment

  • Does not sporulate, therefore boiling and/or sterilization are effective.
  • Sanitize rabbit cages and their entire living areas.
  • Provide rabbits with an appropriate diet   Nutrition: dietary requirements  .

Prevention

  • Provide rabbits with a high fiber diet   Nutrition: dietary requirements  .
  • Provide rabbits with a clean environment.
  • Provide rabbits with adequate living space: plenty of room for exercise and no overcrowding.
  • Decrease stress as much as possible.

Vaccination

  • Some vaccines are available for humans.
  • There are none that are currently commercially available for rabbits.

Other countermeasures

  • While awaiting culture and sensitivity results, administer aggressive supportive and fluid therapy   Fluid therapy  .
  • Prognosis is guarded and depends on severity of disease, strain ofE. coli, immune status of the rabbit, concurrent disease(s), types of co-pathogen(s), etc.
  • Success increases with early intervention.

Diagnosis

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Ravikumar P et al (2014) Evaluation of induced mastitis in rabbits based on clinical parameters, direct microscopic somatic scell count and viable counts of E. coli in milk. J Cell Tissue Res 14 (2), 4367-4372.
  • Lord B (2012) Gastrointestinal disease in rabbits 2. Intestinal diseases. In Pract 34 (3), 156-162 VetMedResource.
  • Ibekwe A M, Grieve C M & Yang C H (2007) Survival of Escherichia coli O157:H7 in soil and on lettuce after soil fumigation. Can J Microbiol 53 (5), 623-635 PubMed.
  • Scaife H R, Cowan D, Finney J et al (2006) Wild rabbits (Oryctolagus cuniculus) as potential carriers of verocytotoxin-producing Escherichia coliVet Rec 159 (6), 175-178 PubMed.
  • Fotadar U, Zaveloff P & Terracio L (2005) Growth of Escherichia coli at elevated temperatures. J Basic Microbiol 45 (5), 403-404 PubMed.
  • García A & Fox J G (2003) The rabbit as a new reservoir host of enterohemorhagic Escherichia coliEmerg Infect Dis (12), 1592-1597 PubMed.
  • Blanco J E, Blanco M, Blanco J et al (1996) O serogroups, biotypes, and eae genes inEscherichia colistrains isolated from diarrheic and healthy rabbits. J Clin Microbiol 34 (12), 3101-3017 PubMed.
  • Whipp S C, Rasmussen M A & Cray W C Jr. (1994) Animals as a source of Escherichia coli pathogenic for human beings. JAVMA 204 (8), 1168-1175 PubMed.
  • Cullor J S (1995) Escherichia coli O157-H7: the silent danger. Vet Med 90 (1), 74-82 VetMedResource.
  • Dorn C R (1995) Escherichia coli O157-H7. JAVMA 206 (10), 1583-1585 PubMed.
  • Licois D (1992) [Enteropathogenic Escherichia coli from the rabbit]. Ann Rech Vet 23 (1), 27-48 PubMed.
  • Levine M M (1987) Escherichia coli that cause diarrhoea - enterotoxigenic, enteropathogenic, enteroinvasive, enterohaemorrhagic and enteroadherent. J Infect Dis 155 (3), 377-89 PubMed.

Other sources of information

  • Centers for Disease Control and Prevention (2015) E. coli (Escherichia coli). Website:www.cdc.gov/ecoli.
  • Vella D (2013) Rabbits. Intestinal Disorders. In:Clinical Veterinary Advisor. Birds and Exotic Pets. Eds: Mayer J & Donnelly T M. Elsevier. pp 385-390. ISBN: 978-1-4160-3969-3.
  • Oglesbee B L & Jenkins J R (2012) Rabbits. Gastrointestinal diseases. In:Ferrets, Rabbits and Rodents: Clinical Medicine and Surgery. 3rd edn. Eds: Quesenberry K E & Carpenter J W. Philadelphia: W B Elsevier Saunders. pp 193-204. ISBN: 978-1-4160-6621-7.
  • O'Malley B (2005) Rabbits. In:Clinical Anatomy and Physiology of Exotic Species. Elsevier Saunders. pp 173-195. ISBN 0 7020 2782 0.

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