A 4-year-old unvaccinated child from an urban slum in Delhi presents with fever, sore throat, and a grayish pseudomembrane. Culture on Loeffler's medium grows gram-positive bacilli. The Elek test is positive. Which of the following is the most appropriate immediate management?

Explanation

## Management of Confirmed Diphtheria **Key Point:** Diphtheria management requires BOTH antitoxin (to neutralize circulating toxin) AND antibiotics (to eliminate the organism and prevent further toxin production). Isolation is mandatory to prevent transmission. **Diagnostic Confirmation:** - Loeffler's medium: selective medium for *Corynebacterium diphtheriae* - Elek test: immunodiffusion test that detects diphtheria toxin production (confirms toxigenic strain) - Gram-positive bacilli: consistent with *C. diphtheriae* **Treatment Regimen:** | Component | Agent | Dose | Duration | |-----------|-------|------|----------| | **Antitoxin** | Horse serum antitoxin | 20,000–100,000 units IV/IM | Single dose | | **Antibiotic** | Penicillin G | 1.2 million units IM/IV q4h | 7–10 days | | **Alternative** | Erythromycin | 500 mg PO q6h | 7–10 days | **Isolation:** - Respiratory isolation until 2 consecutive negative cultures (24 hours apart) after completion of antibiotics - Or until 7 days of appropriate antibiotic therapy **Clinical Pearl:** - Antitoxin is derived from horse serum → risk of serum sickness (5–10%) - Skin test for hypersensitivity should be performed before administration - Antibiotics eliminate the organism but do not neutralize toxin already produced **High-Yield:** Both antitoxin AND antibiotics are essential. Neither alone is sufficient.