Corynebacterium

Corynebacterium is a genus of bacteria, of which the most important is C.diphtheriae, which causes diphtheria.

Pathogenic C. diphtheriae is differentiated from non-pathogenic 'diphtheroids' by:

• pathogenicity tests in vivo
• toxogenicity tests in vitro
• biochemical tests:
  • pathogens generally cannot ferment sucrose or hydrolyse urea
  • C. ulcerans, a pathogen, is an exception in that it can hydrolyse urea
• cultivation:
  • diphtheroids:
    • are more regular in appearance
    • tend to grow side-by-side
    • tend to form black colonies with tellurite medium
  • C. diphtheriae:
  • show pleomorphism of form
    • are irregularly orientated with respect to each other
    • exhibit metachromatic granules
    • tend to form dark grey colonies with tellurite medium

Generic properties are detailed in the submenu.