Clostridium species

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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 botulinum

• Clostridium botulinum has been implicated in equine grass sickness.
• The toxin also causes botulism, a disease affecting muscle at the neuromuscular junction.

Clostridium chauvei

• Causes gas gangrene, along with Clostridium septicum.
• Infects muscles giving black leg myositis

Clostridium novyi

• Causes gas gangrene and myositis.
• May be involved in cutaneous lesions

Clostridium perfringens

• Causes:
  • Lamb dysentery
  • Colitis X.
  • Pulpy kidney disease
    • C. perfringens type D only.
  • Peritonitis in cattle
  • Dysphagia in horses
  • Gas gangrene
  • Myositis

Clostridium septicum

• Causes gas gangrene and myositis

Clostridium sordelli

• Causes gas gangrene and myositis

Clostridium tetani

• Clostridium tetani may infect wounds, giving rise to tetanus

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