Clostridium botulinum

• Ubiquitous organism
• Oval, subterminal endospores; spores survive boiling for hours
• Causes botulism, a potentially fatal intoxication
• Germination of endospores, growth of bacterial cells and toxin production in anaerobic conditions e.g. decaying carcasses and vegetation
• Disease in animals consuming rotting carcasses and in herbivores through contamination of feed
• Pathogenesis:
  • Intoxication on ingestion and absorbtion of toxin from GIT into the blood
  • Occasionally germination of spores in wounds or GIT
  • Neurotoxin carried to peripheral nervous system
  • Toxin binds gangliosides irreversibly at the neuromuscular junction
  • Blocks release of acetylcholine
• Clinical signs:
  • Dilated pupils, dry mucus membranes, decreased salivation, tongue flacidity, dysphagia in farm animals
  • Incoordination and knuckling followed by flacid paralysis and recumbency
  • Paralysis of respiratory muscles leads to death
  • Flacid paralysis of legs and wings in birds
• Diagnosis:
  • Mouse inoculation with infected serum
  • Toxin detection by PCR, ELISA
  • Toxin neutralisation tests in mice
• Treatment: polyvalent antiserum neutralises unbound toxin
• Toxoid vaccine used in endemic regions
• Implicated in equine grass sickness