Clostridium species

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Overview

  • Organisms present in the soil, alimentary tract and faeces
  • Endospores may be present in liver and may be reactivated to cause disease
  • Neurotoxic clostridia, Clostridium tetani and Clostridium botulinum affect neuromuscular function but cause no tissue damage
  • Histotoxic clostridia cause localised lesions in tissues and may cause toxaemia
  • C. perfringens cause inflammatory lesions in the gastrointestinal tract and enterotoxaemia

Characteristics

  • Large Gram-positive rods
  • Obligate anaerobes
  • Fermentative, catalase negative, oxidase negative
  • Straight or slightly curved
  • Motile by flagellae
  • Require enriched media for growth
  • Produce endospores which vary in shape and location and cause bulging of mother cell


Pathogenesis and pathogenicity

Clostridium botulinum

  • Clostridium botulinum has been implicated in equine grass sickness.
  • The toxin also causes botulism, a disease affecting muscle at the neuromuscular junction.

Clostridium chauvei

Clostridium novyi

Clostridium perfringens

Clostridium septicum

Clostridium sordelli

Clostridium tetani

  • Clostridium tetani may infect wounds, giving rise to tetanus

Diagnosis

  • Anaerobic transport medium
  • Culture on blood agar enriched with yeast extract, vitamin K and haemin
  • Anaerobic culture with hydrogen supplement and 5-10% carbon dioxide
  • C. perfringens colonies are surrounded by a zone of double haemolysis
  • Biochemical tests
  • Toxins identified in body fluids by toxin neutralisation or protection tests in lab animals
  • Fluorescent antibody tests for histotoxic clostridia
  • ELISA, PCR for toxin detection