Difference between revisions of "Clostridium species"
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*Neurotoxic clostridia, ''Clostridium tetani'' and ''Clostridium botulinum'' affect neuromuscular function but cause no tissue damage | *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 | *Histotoxic clostridia cause localised lesions in tissues and may cause toxaemia | ||
| − | *''C. perfringens'' cause inflammatory lesions in the gastrointestinal tract and | + | *''C. perfringens'' cause inflammatory lesions in the gastrointestinal tract and enterotoxaemias in sheep |
===Characteristics=== | ===Characteristics=== | ||
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===Pathogenesis and pathogenicity=== | ===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 | ||
Revision as of 14:18, 18 May 2008
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 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
- Causes gas gangrene, along with Clostridium septicum.
- Infects muscles giving black leg myositis
Clostridium novyi
- Causes gas gangrene and myositis.
- May be involved in cutaneous lesions
Clostridium perfringens
- Causes:
- Lamb dysentery
- Colitis X.
- Pulpy kidney disease
- C. perfringens type D only.
- Peritonitis in cattle
- Dysphagia in horses
- Gas gangrene
- Myositis
Clostridium septicum
- Causes gas gangrene and myositis
Clostridium sordelli
- Causes gas gangrene and myositis
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