Difference between revisions of "Clostridium species - Overview"
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| + | ===Overview=== | ||
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| + | *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 | ||
| + | |||
| + | ===Diagnosis=== | ||
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| + | *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 for 48 hours | ||
| + | *Colonies of ''C. perfringens'' are 5mm diameter, circular, flat and grey and surrounded by a zone of double haemolysis | ||
| + | *Positive cAMP test with ''Streptococci agalactiae'' | ||
| + | *Biochemical tests | ||
| + | *Toxins identified in body fluids by toxin neutralisation or protection tests in lab animals | ||
| + | *Nagler reaction to detect alpha toxin - plate neutralisation test | ||
| + | *Fluorescent antibody tests for histotoxic clostridia | ||
| + | *ELISA, PCR for toxin detection | ||
| + | *Sudden death in unvaccinated farm animals may suggest ''C. perfringens'' types B, C and D | ||
| + | *Post mortem | ||
| + | *Gram positive rods present on intestinal smears suggests clostridial enterotoxaemia | ||
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[[Category:Clostridium_species]] | [[Category:Clostridium_species]] | ||
Latest revision as of 14:10, 5 July 2010
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
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 for 48 hours
- Colonies of C. perfringens are 5mm diameter, circular, flat and grey and surrounded by a zone of double haemolysis
- Positive cAMP test with Streptococci agalactiae
- Biochemical tests
- Toxins identified in body fluids by toxin neutralisation or protection tests in lab animals
- Nagler reaction to detect alpha toxin - plate neutralisation test
- Fluorescent antibody tests for histotoxic clostridia
- ELISA, PCR for toxin detection
- Sudden death in unvaccinated farm animals may suggest C. perfringens types B, C and D
- Post mortem
- Gram positive rods present on intestinal smears suggests clostridial enterotoxaemia