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Infectious Diseases

Diphtheria, Cause, Types, Clinical Presentation, Diagnosis and Treatment

Diphtheria is an acute infection caused by Corynebacterium diphtheriae that usually attacks the respiratory tract but may involve any mucous membrane or skin wound.
It Spreads by respiratory secretions.
Age: although it is considered as a disease of childhood, it is increasingly affecting adults due to non- immunization in childhood.
Local manifestations are due to pseudo-membrane while the systemic manifestations are due to the formation of exotoxin. However, the presence of pseudo-membrane is not essential for diagnosis. Exotoxin produced by the organism is responsible for myocarditis and neuropathy.
diphtheria apperance

Nasal diphtheria

It is characterized by the presence of unilateral, serosanguineous nasal discharge that crusts around the external nares.

Pharyngeal diphtheria

It is the most common type of diphtheria and is associated with the greatest toxicity. It is characterized by marked tonsillar and pharyngeal inflammation and the presence of pseudo-membrane. This tough greyish yellow membrane is formed by fibrin, bacteria, epithelial cells, mononuclear cells and polymorph and is firmly adherent to the underlying tissue. Regional lymph nodes are enlarged and tender.

Laryngeal diphtheria

Laryngeal diphtheria causes husky voice brassy cough and later dyspnea and cyanosis due to respiratory obstruction.

Other Manifestations:

Myocarditis develops often weeks later in with pharyngeal or laryngeal diphtheria.

Neurological manifestations
  • Palatal and pharyngeal wall palsy.
  • Cranial nerve palsies,
  • Paraesthesia
  • Polyneuropathy
  • Rarely encephalitis.

Cutaneous diphtheria
It is usually associated with bums and in poor personal hygiene.
cutaneous diphtheria


Diagnosis is clinical but can be confirmed by culture of the organism.

Differential Diagnosis of Diphtheria

Prevention of Diphtheria

1. DPT in childhood.
2. Adult-type toxoid (Td) in adults.

Treatment of Diphtheria

1. Complete isolation of patient, bed rest.

2. Anti-toxin prepared from horse serum for all cases when diphtheria is suspected. It must be given early because to prevent further fixation of the toxin to tissue receptors since fixed toxin is not neutralized by anti-toxin.

3. Removal of the membrane by direct laryngoscopy or bronchoscopy may be necessary to prevent or alleviate airway obstruction.

4. Antibiotics
Erythromycin 500 mg 5- hourly for 14 days Clarithromycin or azithromycin may be used

Prophylactic treatment
Contacts to the case should receive erythromycin 500 mg 6- hourly for 7 days to eradicate carriage

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