Difference between revisions of "Clostridium species"

From WikiVet English
Jump to navigation Jump to search
(Redirected page to Category:Clostridium species)
 
(42 intermediate revisions by 6 users not shown)
Line 1: Line 1:
<big><center>[[Infectious agents and parasites|'''BACK TO INFECTIOUS AGENTS AND PARASITES''']]</center></big>
+
#REDIRECT[[:Category:Clostridium species]]
<big><center>[[Bacteria|'''BACK TO BACTERIA''']]</center></big>
 
 
 
===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 [[Tremors and Movement Disorders - Nervous System#Tetanus|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 [[Muscles - degenerative#Botulism|botulism]]
 
*Toxin produced in decaying organic matter absorbed from GIT into the blood and affects neuromuscular junction
 
*Implicated in [[Intestines - physical disturbances#Equine dysautonomia, or grass sickness|equine grass sickness]]
 
 
 
 
 
===Clostridium chauvei===
 
 
 
* Causes [[General Pathology - Necrosis#Gas Gangrene|gas gangrene]], along with [[Clostridium species#Clostridium septicum|''Clostridium septicum'']].
 
* Infects muscles giving black leg [[Muscles - inflammatory#Black leg|myositis]]
 
 
 
===Clostridium novyi===
 
 
 
* Causes [[General Pathology - Necrosis#Gas Gangrene|gas gangrene]] and [[Muscles - inflammatory#Gas gangrene|myositis]].
 
*May be involved in [[Bacterial skin infections#Systemic bacterial infections|cutaneous lesions]]
 
 
 
===Clostridium perfringens===
 
 
 
* Causes:
 
** [[Intestines - Fibrinous/ Haemorrhagic Enteritis#Lamb Dysentery (Enterotoxaemia with Blood)|Lamb dysentery]]
 
** [[Intestines - Fibrinous/ Haemorrhagic Enteritis#Colitis X|Colitis X]].
 
** [[Intestines - Catarrhal Enteritis#"Pulpy Kidney" Disease|Pulpy kidney disease]]
 
*** ''C. perfringens'' type D only.
 
** [[Peritoneal cavity - inflammatory#In cattle|Peritonitis in cattle]]
 
**  [[Respiratory system - clinical signs#Dysphagia|Dysphagia in horses]]
 
** [[General Pathology - Necrosis#Gas Gangrene|Gas gangrene]]
 
** [[Muscles - inflammatory#Gas gangrene|Myositis]]
 
 
 
===Clostridium septicum===
 
 
 
* Causes [[General Pathology - Necrosis#Gas Gangrene|gas gangrene]] and [[Muscles - inflammatory#Gas gangrene|myositis]]
 
 
 
===Clostridium sordelli===
 
 
 
* Causes [[General Pathology - Necrosis#Gas Gangrene|gas gangrene]] and [[Muscles - inflammatory#Gas gangrene|myositis]]
 
 
 
 
 
 
 
===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
 

Latest revision as of 10:40, 12 May 2010