A 28-year-old woman from rural Maharashtra presents with a 3-day history of severe sore throat, fever (39.5°C), and difficulty swallowing. On examination, she has bilateral exudative pharyngitis with enlarged tonsils, petechial rash on the soft palate, and tender cervical lymphadenopathy. A rapid antigen detection test (RADT) for Group A Streptococcus is positive. She has no history of penicillin allergy. Which of the following is the most appropriate antibiotic therapy?

Explanation

## Streptococcus pyogenes Acute Pharyngitis: Treatment **Key Point:** Penicillin V (oral) or amoxicillin (oral) is the first-line antibiotic for Group A Streptococcus pharyngitis in non-penicillin-allergic patients, given for 10 days to eradicate the organism and prevent suppurative and non-suppurative sequelae. **High-Yield:** The standard dosing for amoxicillin in GAS pharyngitis is 500 mg orally three times daily (or 250 mg three times daily for lighter patients) for a full 10-day course. This achieves adequate pharyngeal and tonsillar penetration. ### Why Amoxicillin is Preferred | Feature | Amoxicillin | Azithromycin | Cephalexin | Clindamycin | |---------|-------------|--------------|-----------|-------------| | **First-line status** | Yes | No (macrolide resistance ↑) | Alternative (if PCN allergy) | Alternative (if PCN allergy) | | **Dosing frequency** | TID | Once/twice daily | QID | TID | | **10-day compliance** | Better (fewer doses) | Shorter course (5 days) | Acceptable | Acceptable | | **Cost** | Low | Moderate | Moderate | Moderate | | **Resistance** | Rare in GAS | Rising (15–30% in India) | Rare | Rare | **Clinical Pearl:** The 10-day course is critical—shorter courses (even if microbiologically effective) carry a higher risk of acute rheumatic fever (ARF) and post-streptococcal glomerulonephritis (PSGN). This is especially important in India, where ARF incidence remains high. **Mnemonic:** **PENICILLIN FIRST** — Penicillin V or amoxicillin is the gold standard; alternatives (cephalosporins, macrolides, clindamycin) are reserved for allergy or resistance. ### Rationale for Correct Answer Amoxicillin 500 mg TID × 10 days: - Bactericidal β-lactam with excellent GAS susceptibility - Oral bioavailability superior to penicillin V in some regions - Achieves therapeutic levels in pharyngeal tissue - 10-day duration prevents sequelae (ARF, PSGN) - No penicillin allergy documented in this patient [cite:Harrison 21e Ch 329]