Difference between revisions of "Clostridium species"

From WikiVet English
Jump to navigation Jump to search
(Redirected page to Category:Clostridium species)
 
(38 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 damaged tissues e.g. penetrating wounds
 
**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 across synapse to terminals of inhibitory neurons where they block transmission of signals
 
**Spastic paralysis by constant tensing of muscles results
 
**Toxin can be blood-borne and bind to motor terminals throughout the body as well as in the CNS
 
*Clinical signs:
 
**Incubation period 5-10 days
 
**Stiffness, localised spasms, altered heart and respiratory rates, dysphagia, altered facial expression, lock-jaw from mastigatory muscle spasm
 
**Tonic muscle contraction easily stimulated
 
*Treatment:
 
**Antitoxin IV or into subarachnoid space on 3 consecutive days
 
**Toxoid subcutaneously to promote active immune response
 
**Penicillin to kill vegetative cells
 
**Debridement and flushing of wound with hydrogen peroxide
 
**Fluids, sedatives, muscle relaxants
 
*Control:
 
**Toxoid vaccine for farm animals
 
**Debridement of wounds in horses
 
 
 
 
 
===''Clostridium botulinum''===
 
 
 
*Ubiquitous organism
 
*Oval, subterminal endospores; spores survive boiling for hours
 
*Causes [[Muscles - degenerative#Botulism|botulism]], a potentially fatal intoxication
 
*Germination of endospores, growth of bacterial cells and toxin production in anaerobic conditions e.g. decaying carcasses and vegetation
 
*Disease in animals consuming rotting carcasses and in herbivores through contamination of feed
 
*Pathogenesis:
 
**Intoxication on ingestion and absorbtion of toxin from GIT into the blood
 
**Occasionally germination of spores in wounds or GIT
 
**Neurotoxin carried to peripheral nervous system
 
**Toxin binds gangliosides irreversibly at the neuromuscular junction
 
**Blocks release of acetylcholine
 
*Clinical signs:
 
**Dilated pupils, dry mucus membranes, decreased salivation, tongue flacidity, dysphagia in farm animals
 
**Incoordination and knuckling followed by flacid paralysis and recumbency
 
**Paralysis of respiratory muscles leads to death
 
**Flacid paralysis of legs and wings in birds
 
 
 
*Toxoid vaccine
 
*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