BACTERIA

Corynebacterium diphtheriae animated Corynebacterium diphtheriae infections

Corynebacterium diphtheriae appearance

  • Gram-positive, rod-like bacteria, arranged usually in a palisade
  • often with club shaped swellings at the poles
  • generally with irregularly staining segments or granules (metachromatic granules)
  • nonmotile
  • non-spore-forming

Infections caused by Corynebacterium diphtheriae

Corynebacterium diphtheriae is the pathogenic bacterium that causes diphtheria. Four subspecies are recognized. All may be toxigenic (and therefore cause diphtheria) or not toxigenic. C. diphtheriae produces diphtheria toxin which alters protein function in the host by inactivating the elongation factor EF-2. This causes pharyngitis and 'pseudomembrane' in the throat. The diphtheria toxin gene is encoded by a bacteriophage found in toxigenic strains, integrated into the bacterial chromosome (Wikipedia).

In areas where diphtheria is endemic, C. diphtheriae in the nasopharyngeal passageways is common. Toxigenic strains in susceptible individuals can cause disease by multiplying and secreting diphtheria toxin into either skin or nasopharyngeal lesions. The diphtheritic lesion is often covered by a pseudomembrane composed of fibrin, bacteria, and inflammatory cells.

A milder form of diphtheria can be restricted to the skin. Less common consequences include myocarditis (about 20% of cases) and peripheral neuropathy (about 10% of cases) (Wikipedia).

Deaths caused by Corynebacterium diphtheriae (2004)

  • Worldwide incidence:
    34,000
  • Worldwide deaths:
    5,000

Corynebacterium diphtheriae treatment

Diphtheria antitoxin

Macrolides
  • erythromycin

Penicillins
  • penicillin G

Alternative: