Difference between revisions of "Clostridium species"

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#REDIRECT[[:Category:Clostridium species]]
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<big><center>[[Infectious agents and parasites|'''BACK TO INFECTIOUS AGENTS AND PARASITES''']]</center></big>
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<big><center>[[Bacteria|'''BACK TO BACTERIA''']]</center></big>
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===Overview===
 +
 
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*Organisms present in the soil, alimentary tract and faeces
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*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
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*Histotoxic clostridia cause localised lesions in tissues and may cause toxaemia
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*''C. perfringens'' cause inflammatory lesions in the gastrointestinal tract and enterotoxaemias in sheep
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 +
 
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===Characteristics===
 +
 
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*Large Gram-positive rods
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*Obligate anaerobes
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*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
 +
 
 +
 
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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
 +
*Found in horse faeces
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*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
 +
**Neurotoxin binds irreversibly to ganglioside receptors on motor neurons and is transported to nerve cell body
 +
**Toxins transported to terminals of inhibitory neurons where they block transmission of signals
 +
**Spastic paralysis results
 +
**Toxin can be blood-borne and bind to motor terminals throughout the body as well as in the CNS
 +
*Clinical signs:
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**
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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 chauvei===
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* Causes [[General Pathology - Necrosis#Gas Gangrene|gas gangrene]], along with [[Clostridium species#Clostridium septicum|''Clostridium septicum'']].
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* Infects muscles giving black leg [[Muscles - inflammatory#Black leg|myositis]]
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===Clostridium novyi===
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* Causes [[General Pathology - Necrosis#Gas Gangrene|gas gangrene]] and [[Muscles - inflammatory#Gas gangrene|myositis]].
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*May be involved in [[Bacterial skin infections#Systemic bacterial infections|cutaneous lesions]]
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===Clostridium perfringens===
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* Causes:
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** [[Intestines - Fibrinous/ Haemorrhagic Enteritis#Lamb Dysentery (Enterotoxaemia with Blood)|Lamb dysentery]]
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** [[Intestines - Fibrinous/ Haemorrhagic Enteritis#Colitis X|Colitis X]].
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** [[Intestines - Catarrhal Enteritis#"Pulpy Kidney" Disease|Pulpy kidney disease]]
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*** ''C. perfringens'' type D only.
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** [[Peritoneal cavity - inflammatory#In cattle|Peritonitis in cattle]]
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**  [[Respiratory system - clinical signs#Dysphagia|Dysphagia in horses]]
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** [[General Pathology - Necrosis#Gas Gangrene|Gas gangrene]]
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** [[Muscles - inflammatory#Gas gangrene|Myositis]]
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===Clostridium septicum===
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* Causes [[General Pathology - Necrosis#Gas Gangrene|gas gangrene]] and [[Muscles - inflammatory#Gas gangrene|myositis]]
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===Clostridium sordelli===
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* Causes [[General Pathology - Necrosis#Gas Gangrene|gas gangrene]] and [[Muscles - inflammatory#Gas gangrene|myositis]]
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 +
 
 +
 
 +
===Diagnosis===
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*Anaerobic transport medium
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*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

Revision as of 14:55, 18 May 2008

BACK TO INFECTIOUS AGENTS AND PARASITES
BACK TO BACTERIA

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
    • Neurotoxin binds irreversibly to ganglioside receptors on motor neurons and is transported to nerve cell body
    • Toxins transported to terminals of inhibitory neurons where they block transmission of signals
    • Spastic paralysis results
    • Toxin can be blood-borne and bind to motor terminals throughout the body as well as in the CNS
  • Clinical signs:


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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