Diphtheria Overview and Clinical Findings

Diphtheria

• Classified as a childhood bacterial disease, incidence rate low due to vaccination programs
• Gram-positive, club-shaped bacteria, forming various shapes (e.g., letter-like/L-forms)
• Contains metachromatic granules that store energy (visible when stained with methylene blue)
• Three species: C. diphtheriae gravis, C. diphtheriae mitis
• Transmission: Respiratory droplets and direct contact; also, occurs in the upper respiratory tract
• Risk factors: Unvaccinated children, incomplete doses of vaccination, immunocompromised individuals (e.g., using corticosteroids long-term), or those with chronic conditions, transplant recipients.
• Pathogenesis: Bacteria invade, multiply locally, producing a potent exotoxin. The exotoxin is a major cause of disease pathology.

Clinical Findings

• Incubation period: 2-6 days
• Commonly affected sites: Tonsils, soft palate, larynx, nose.
• Characteristic feature: Formation of a thick, gray pseudomembrane on tonsils/throat.
• Other clinical signs: Dirty brown/green discolouration, inflammatory exudate, leukocytes, fibrin, and desquamated epithelial cells.
• Membranes are difficult to dislodge. Dislodging causes bleeding from the underlying tissues.
• Additional clinical findings: Fever, sore throat, cervical lymphadenopathy (bilateral swelling of lymph nodes in the neck), bull-neck appearance (a characteristic facial feature).

Complications

• Airway obstruction due to membrane formation
• Myocarditis, causing arrhythmias and shock
• Neurological issues: Weakness, paralysis
• Rarely: Perforation of the soft palate, allowing food to enter the infection site (potentially causing infection).

Lab Diagnosis

• Specimen: Throat swab
• Gram stain: Observing tapered, pleomorphic gram-positive rods, and metachromatic granules
• Culture: Löffler's medium or tellurite blood agar for growth observation of gray-black colonies.
• Toxin production test: Elek's test for identification
• Animal inoculation test: testing for toxin production-

Treatment

• Treatment of choice: Antitoxin (toxoid) (20,000-100,000 units intravenously)
• Prior hypersensitivity testing on forearm to evaluate the potential reaction prior to full dose administration, using a small initial dose.
• Treatment timing: Immediate, based on clinical suspicion.
• Alternative agents: Erythromycin as an alternative for those with penicillin allergies.

Prevention

• Diphtheria toxoid: Prepared by treating the toxin with formalin.
• Combined vaccine: Diphtheria toxoid, tetanus toxoid, and acellular pertussis vaccine (DPT).
• Vaccination schedule: Three doses at one-month intervals, starting from 45 days after birth.
• Importance: Regular vaccinations are crucial for disease prevention.