Difference between revisions of "Category:Clostridium species"

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===[[Enteropathogenic and Enterotoxaemic Clostridia]]===
 
 
  
  

Revision as of 11:11, 12 May 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


<ncl style=compact maxdepth=4 headings=bullet headstart=2 showcats=1 showarts=1>Category:Clostridium species</ncl>


C. piliforme

  • Spore-forming filamentous Gram negative intracellular pathogen
  • Only grows in tissue culture or embryonated eggs
  • Causes Tyzzer's disease - severe hepatic necrosis
  • Sporadic disease in foals, calves, dogs, cats
  • Foals under 6 weeks, found dead or comatose
  • Incubation period up to 1 week
  • Depression, anorexia, fever, jaundice, diarrhoea
  • Hepatomegaly and necrosis on post mortem
  • Diagnosis: Warthin-Starry silver impregnation technique demonstrates organisms in hepatocytes


C. difficile

  • Dogs with chronic diarrhoea
  • New born foals with haemorrhagic enterocolitis
  • Possibly associated with acute colitis in adult horses following antibiotic therapy or grain overload


C. colinum

  • Enteritis in poulty and game birds
  • Shed in faeces of clinically affected and carrier birds
  • Intestinal ulceration and hepatic necrosis
  • Therapeutic antibiotics in drinking water

C. spiroforme

  • Spontaneous and antibiotic-induced enteritis in rabbits
  • Enterotoxaemia, fatal within 48 hours
  • Oral antibiotics upset the intestinal flora, allowing overgrowth of clostridia

Subcategories

This category has the following 3 subcategories, out of 3 total.

Pages in category "Clostridium species"

The following 5 pages are in this category, out of 5 total.