Corynebacterium diphtheriae.

• Gram positive rods in pallisades or Chinese letter formation.
• Entry: inhalation of respiratory droplets.
• Remains localized in the oropharynx, no dissemination.
• Damage due to an exotoxin that inhibits translation.
• Characteristic pseudomembrane on the back of the throat.
• Causes the disease Diphtheria.
• Diphtheria symptoms: sore throat, fever, malaise.

  
  

  Characteristic symptoms: bull neck swelling and pseudomembrane formation.
• The pseudomembrane is composed of bacteria, dead epithelial cells and immune cells. Can lead to difficulty breathing and respiratory blockage.
• In healthy adults, is generally self limiting and cleared within a week.
• In children, immune compromised people or chronic pulmonary problems can cause neurologic and cardiac symptoms (toxin activity, not dissemination).
• Diphtheria toxin binds to heparin binding epidermal growth factor, which is abundant on heart and nerve cells.

  
  

  Leads to death of these cells causing impairment of the nervous system and heart function (causes congestive heart failure and cardia arrhythmia) or death.
• Diphtheria toxin genes come from a temperate bacteriophage.
• Diphtheria toxin is extremely potent.
• Treatment:

  Antibiotics: penicillin or erythromycin.

  Diphtheria antitoxin to neutralize the circulating toxin.

  Immunization with diphtheria toxoid vaccine.