Changes

Jump to navigation Jump to search
no edit summary
Line 1: Line 1:  +
 +
===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
 +
 +
 +
 +
 +
 
[[Category:Clostridium_species]]
 
[[Category:Clostridium_species]]
Author, Donkey, Bureaucrats, Administrators
53,803

edits

Navigation menu