Diphtheria Dental Notes – NBDE, NEET MDS, Board Exams

Diphtheria Dental Notes for NBDE, NEET MDS preparation and Dental Board Exams

Overview:

• Causative Agent: Corynebacterium diphtheriae, and less commonly C. ulcerans and C. pseudotuberculosis.
• Transmission: Spread through contact with infected individuals or carriers, and in rare cases, contact with farm animals or unpasteurized dairy products.

Epidemiology:

• History: Identified by Klebs in 1883; antitoxin developed by Emil von Behring, Nobel Prize in Medicine, 1901.
• Impact of Vaccination: Significant decline in cases since routine immunization started in the early 20th century.
• Recent Trends: Outbreaks in post-Soviet states during the 1990s, resurgence in populations with inadequate vaccination.

Pathogenesis:

• Mechanism: The bacterium produces a potent exotoxin leading to tissue necrosis, which facilitates further bacterial growth and toxin spread.

Clinical Features:

• Incubation Period: 1 to 5 days.
• Symptoms: Low-grade fever, headache, malaise, anorexia, sore throat, vomiting.
• Signs: Nasal discharge, pharyngeal and tonsillar grayish membrane formation, possible airway obstruction, bull neck due to cervical lymphadenopathy.
• Complications: Myocarditis, neuropathy resembling Guillain-Barré syndrome, cutaneous lesions, systemic toxicity.

Diagnosis:

• Clinical Signs: Distinctive membrane on tonsils and throat; severe cases show airway obstruction.
• Laboratory Confirmation: Culture and PCR analysis; essential for confirmation due to the rarity and potential severity of the disease.
• Confirmatory testing for diphtheria includes culture to identify the bacterial species and the Elek test to confirm diphtheria toxin production. (ref)

Treatment:

• Antitoxin: Critical for neutralizing unbound circulating toxin; must be administered promptly.
• Antibiotics: Erythromycin or penicillin to eradicate bacterial infection and halt toxin production.
• Isolation: Patients considered infectious until three consecutive negative cultures post-treatment.

Prevention:

• Vaccination: Primary prevention through DTP or Tdap vaccine, booster required every 10 years.

Mnemonics for Memorizing Diphtheria Features:

• “CUTERP” Mnemonic for Key Clinical Signs:
  • C – Corynebacterium causes it
  • U – Uvula and tonsil membrane formation
  • T – Toxin production causing tissue necrosis
  • E – Exudate that is gray and adherent
  • R – Respiratory complications including stridor
  • P – Prevention by vaccine and prompt antitoxin

Summary Table for Quick Revision:

Feature	Details
Etiology	Corynebacterium diphtheriae
Transmission	Contact with infected individuals/carriers
Symptoms	Fever, sore throat, malaise, membrane on tonsils
Complications	Myocarditis, airway obstruction, neuropathy
Diagnosis	Membrane appearance, culture, PCR
Treatment	Antitoxin immediately, antibiotics (erythromycin, penicillin)
Prevention	DTP/Tdap vaccine, boosters every 10 years

Extra Points:

Pharyngeal and Tonsillar Diphtheria:

• Common sites of infection: pharynx and tonsils
• Symptoms:
  • Gradual onset of pharyngitis
  • Early symptoms: malaise, sore throat, anorexia, low-grade fever
  • Formation of bluish-white membrane in 2 to 3 days
  • Membrane may extend from tonsils to soft palate
  • Membrane color may change to greyish-green or black
  • Minimal mucosal erythema surrounding the membrane
  • Firmly adherent membrane causing bleeding upon removal
  • Extensive membrane formation may lead to respiratory obstruction
  • Severe cases: marked edema, lymphadenopathy, “bull neck” appearance, systemic symptoms like prostration, stupor, coma
  • Death can occur within 6 to 10 days

Laryngeal Diphtheria:

• Symptoms: fever, hoarseness, barking cough
• Membrane formation can lead to airway obstruction, coma, and death

Anterior Nasal Diphtheria:

• Onset similar to common cold
• Symptoms: mucopurulent nasal discharge, blood-tinged discharge
• White membrane formation on nasal septum
• Usually mild due to poor systemic absorption of toxin

Cutaneous Diphtheria:

• Manifestations: scaling rash, ulcers with clear edges and membrane
• Common in tropics, less severe systemic complications compared to other forms
• Cutaneous cases in the US typically nontoxigenic, but toxigenic cases increasing

Other Rare Sites of Involvement:

• Mucous membranes of conjunctiva, vulvovaginal area, external auditory canal

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