Diphtheria
Diphtheria is an acute, toxin-mediated infectious disease caused by Corynebacterium diphtheriae, characterized by the formation of a tough, gray-white pseudomembrane on mucous membranes.
1. Pathogenesis & Clinical Presentation
- Mechanism: Exotoxin production (inhibits protein synthesis by ADP-ribosylation of EF-2).
- Pseudomembrane: Firmly adherent, bleeds on removal; usually involves tonsils, pharynx, or larynx.
- Bull Neck: Massive cervical lymphadenopathy and edema characteristic of severe pharyngeal involvement.
2. Complications & Diagnosis
| Complication | Clinical Significance |
|---|---|
| Cardiac | Myocarditis (leading cause of death). |
| Neurologic | Polyneuritis (often manifesting as palatal paralysis). |
| Respiratory | Airway obstruction (croup-like symptoms). |
3. Management Principles
- Antitoxin: The cornerstone of therapy; should be administered immediately based on clinical suspicion, without waiting for culture confirmation.
- Antibiotics: Erythromycin or Penicillin are used to eliminate the organism and prevent the carrier state.
NEET PG Hint: Remember the “Bull Neck” appearance and that the pseudomembrane bleeds on removal (key differentiator from fungal thrush). Treatment is **clinical**; never delay antitoxin for laboratory reports. Also, recall that palatal paralysis is a common early sign of neurotoxicity.