ISSN 2398-2942      

Clostridium tetani

icanis
Contributor(s):

Melissa Kennedy


Introduction

Classification

Taxonomy

  • Genus: Clostridium.
  • Family: Bacillaceae.
  • Species: tetani.

Etymology

  • Gk: kloster - spindle.
  • Gr: tetanos - tension.

Active Forms

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Resting Forms

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Clinical Effects

Epidemiology

Habitat

  • The spores of C. tetani are widely distributed in soil.
  • Often transiently present in the gastrointestinal tract of animals.

Lifecycle

  • Spores germinate in an anaerobic environment, such as devitalized tissue.
  • Proliferation of the bacterium results in neurotoxin production.

Transmission

  • From soil.
  • Spores are introduced into wounds from soil.

Pathological effects

  • Acquired resistance depends on circulating antitoxin.
  • Surviving animals are susceptible to reinfection.
  • Dogs, and even more so cats, relatively resistant to tetanus Tetanus.
  • The endospores enter wounds or trauma sites, eg through the umbilicus, or after castration Castration , or into the uterus after dystocia Dystocia.
  • Anaerobic conditions are provided by the presence of facultative anaerobes and the spores germinate.
  • The cells multiply and produce 2 exotoxins:
    • Tetanolysin (a hemolysin), which is apparently insignificant.
    • Neurotoxic tetanospasmin, which travels along the peripheral nerves and binds to specific gangliosides of the motor nerve terminals and causes spastic paralysis and the characteristic spasms.
  • Toxin may enter bloodstream and affect most susceptible motor nerve centers, which are those that serve the head and neck - first sign in this case is protruding third eyelid, tetanic spasm of facial and jaw muscle ('lock jaw').
  • Wounds near head → more rapid onset of generalized signs.
  • Localized tetanus can occur - stiffness of muscle or entire limb near wound site.

Other Host Effects

  • Transient in the intestinal tract; commensals unless they gain access to wounds or traumatized tissue.

Control

Control via animal

  • Clean and debride wounds.

Control via chemotherapies

  • Sedatives.
  • Supportive care.
  • Penicillin G Benzylpenicillin.
  • Antitoxin:
    • Does not hasten recovery, as bound toxin is cleared slowly.
    • Binds unbound toxin.

Vaccination

  • Tetanus toxoid vaccines available.

Other countermeasures

  • Prompt administration of anti-toxin.
  • Supportive treatment: sedatives and muscle relaxants.
  • Nursing care.
  • Some have suggested intra-thecal administration of anti-toxin to horses, but this is not currently recommended.

Diagnosis

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Dieringer T M & Wolf A M (1991) Esophageal hiatal hernia and megaesophagus complicating tetanus in two dogs. JAVMA 199 (1), 87-89 PubMed.

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