Clostridium tetani

• Clostridia are large anaerobic, gram positive, motile rods
• Clostridium tetani - tetanus

  Clostridium botulinum - botulism

  Clostridium perfringens - gas gangrene, food poisoning

  Clostridium difficile - pseudomembranous colitis, antibiotic associated diarrhoea
• Normal habitat is the soil or in the intestinal tract of humans and animals.
• Morphology and staining

  • motile by peritrichous flagella
  • terminal spore - drumstick appearance
  • With acid fast method of spore,
  • stain spores - stained red
  • bacillary body - stained blue
• Culture

  • obligate anaerobes
  • haemolysis (+)

  -Anaerobic culture medium

  • Robertson's cooked meat broth
  • Brewer's thioglycollate broth
• Toxin

  • (neurotoxin, tetanospasmin, and tatanolysin) - exotoxin
• Pathogenesis

  • C.tetani is not an invasive organism.
  • strictly localized in the area of devitalized tissue
  • the toxin reaches the central nervous system and becomes fixed to receptors in the spinal cord and brainstem
  • toxin initially binds to receptors on the presynaptic membranes of motor neurons
  • neurotoxin(tetanospasmin) blocks release of inhibitory neurotransmitters resulting in tetanus disease named spastic paralysis
• Clinical findings

  • muscles of the jaw(trismus, lockjaw), contract so that mouth cannot be opened
  • any external stimulus may precipitate a tetanic generalized muscle spasms
  • pain and stiffness in the neck and back
  • fascial spasms produce "sardonic grin" and spasm of the back muscles produce opisthotonus(extreme arching of the back)
• Diagnosis

  • diagnosis rests on clinical picture and history of injury
  • anaerobic culture
  • production of toxin
• Prevention and Control

  1. Active immunization
  2. Proper care of wounds
  3. prophylactic use of antitoxin
  4. administration of penicillin