• An upper respiratory tract illness caused by Corynebacterium diphtheriae, an anerobic Gram positive bacteria
  • Children are usually vaccinated with the DPT vaccine[1]

Clinical Features

  • Symptoms usually begin 5-7 days post initial infection and are often nonspecific mailaise and fatigue
  • Fever of 38°C (100.4°F)
  • Cyanosis in severe disease
  • Sore throat ± difficulty swallowing
  • Hoarseness, cough
  • Lymphadenopathy
  • "Bull neck" in laryngeal diphtheria[2]
  • Dense, grey pseudomembrane covering the posterior aspect of the pharynx[2]
  • Croup-like cough

Systemic Manifestations

Diphtheria toxin can lead to toxin damage of the heart (myocarditis), nervous system, and kidneys

  • Myocarditis
    • Occurs in 10 to 25% of patients
    • Typically occurs 7 to 14 days after onset of respiratory symptoms
    • Heart block, arrhythmias, heart failure, circulatory collapse.
  • Neurologic toxicity
    • Occurs in 5% of patients
    • Local neuropathies are followed by cranial neuropathies

Differential Diagnosis

Acute Sore Throat

Bacterial infections

Viral infections





  • Throat culture will provide definitive diagnosis


  • Airborne isolation
  • Severe disease with respiratory compromise may require intubation
  • Diphtheria antitoxin is not recommended in prophylaxis but can be used to treat confirmed disease[4]
    • Antitoxin will not neutralize toxin that is already fixed to tissues, but it will neutralize circulating (unbound) toxin and will prevent progression of disease
    • Administration should be with an ID specialist at the CDC Emergency Operations Center at (US phone: 770-488-7100)

Treatment Antibiotics


  • Erythromycin 40mg/kg/day maximum, 2 gm/day
  • Procaine penicillin G daily, IM (300,000 U/day for those weighing 10 kg or less, and 600,000 U/day for those weighing more than 10 kg) for 14 days.

Post-Exposure Prophylaxis

Given to close contacts, especially household contacts

  1. Diphtheria booster[4]
  2. Antibiotics (one of the following):
    • Benzathine Penicillin G
      • 600,000 units for persons younger than 6 years old
      • 1,200,000 units for those 6 years old and older
    • Erythromycin 40mg/kg/day for children and 1 g/day for adults x 10 days


  • Admission for disease with moderate to severe respiratory symptoms or while awaiting cultures due to high disease suspicion in an unvaccinated host


  1. Centers for Disease Control and Prevention. Advisory Committee on Immunization Practices (ACIP) Recommended Immunization Schedules for Persons Aged 0 Through 18 Years and Adults Aged 19 Years and Older -- United States, 2013. MMWR. 2013;62(Suppl 1):1-19
  2. MacGregor RR. Corynebacterium diphtheriae. In: Mandell GL, Bennett JE, Dolan R, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, PA: Elsevier Saunders; 2009:chap 205
  3. Melio, Frantz, and Laurel Berge. “Upper Respiratory Tract Infection.” In Rosen’s Emergency Medicine., 8th ed. Vol. 1, n.d.
  4. http://www.cdc.gov/vaccines/pubs/pinkbook/downloads/dip.pdf
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