Difference between revisions of "Clostridium species"

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===Clostridium botulinum===
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===''Clostridium tetani''===
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*Causes [[Tremors and Movement Disorders - Nervous System#Tetanus|tetanus]]
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*Acute, potentially fatal intoxication affecting many species
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*Horses and man particularly susceptible; carnivores fairly resistant
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*Found in horse faeces
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*Characteristics:
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**Terminal, spherical endospores give mother cells a drumstick appearance
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**Enodospores resistant to boiling and chemicals but susceptible to autoclaving
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**Swarming growth and haemolytic on blood agar
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**Many serotypes but all produce same neurotoxin, tetanospasmin, therefore antibodies neutralise all
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*Pathogenesis:
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**Endospores introduced via damaaged tissues e.g. penetrating wounds
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**Anaerobic conditions in the damaged tissue creates an anaerobic environment, allowing germination of spores
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**Tetanospasmin made by bacteria replicating in damaged tissue
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**Absorbed toxin affects neuromuscular junction distant from site of toxin production
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**
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===''Clostridium botulinum''===
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*
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*The toxin also causes [[Muscles - degenerative#Botulism|botulism]]
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*Toxin produced in decaying organic matter absorbed from GIT into the blood and affects neuromuscular junction
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*Implicated in [[Intestines - physical disturbances#Equine dysautonomia, or grass sickness|equine grass sickness]]
  
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* ''Clostridium botulinum'' has been implicated in [[Intestines - physical disturbances#Equine dysautonomia, or grass sickness|equine grass sickness]].
 
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* The toxin also causes [[Muscles - degenerative#Botulism|botulism]], a disease affecting muscle at the neuromuscular junction.
 
  
 
===Clostridium chauvei===
 
===Clostridium chauvei===
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* Causes [[General Pathology - Necrosis#Gas Gangrene|gas gangrene]] and [[Muscles - inflammatory#Gas gangrene|myositis]]
 
* Causes [[General Pathology - Necrosis#Gas Gangrene|gas gangrene]] and [[Muscles - inflammatory#Gas gangrene|myositis]]
  
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===Clostridium tetani===
 
  
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* ''Clostridium tetani'' may infect wounds, giving rise to [[Tremors and Movement Disorders - Nervous System#Tetanus|tetanus]]
 
  
 
===Diagnosis===
 
===Diagnosis===

Revision as of 14:38, 18 May 2008

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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 enterotoxaemias in sheep

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

  • Produce extracellular digestive enzymes and toxic substance known as exotoxins
  • Exotoxins cause necrosis, haemolysis and death
  • Collagenase, hyaluronidase and DNase enymes facilitate spread through tissues


Clostridium tetani

  • Causes tetanus
  • Acute, potentially fatal intoxication affecting many species
  • Horses and man particularly susceptible; carnivores fairly resistant
  • Found in horse faeces
  • Characteristics:
    • Terminal, spherical endospores give mother cells a drumstick appearance
    • Enodospores resistant to boiling and chemicals but susceptible to autoclaving
    • Swarming growth and haemolytic on blood agar
    • Many serotypes but all produce same neurotoxin, tetanospasmin, therefore antibodies neutralise all
  • Pathogenesis:
    • Endospores introduced via damaaged tissues e.g. penetrating wounds
    • Anaerobic conditions in the damaged tissue creates an anaerobic environment, allowing germination of spores
    • Tetanospasmin made by bacteria replicating in damaged tissue
    • Absorbed toxin affects neuromuscular junction distant from site of toxin production


Clostridium botulinum

  • The toxin also causes botulism
  • Toxin produced in decaying organic matter absorbed from GIT into the blood and affects neuromuscular junction
  • Implicated in equine grass sickness


Clostridium chauvei

Clostridium novyi

Clostridium perfringens

Clostridium septicum

Clostridium sordelli


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
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