Antibiotic Treatment for Bacterial Tonsillitis
Amoxicillin or penicillin V should be used as first-line treatment for bacterial tonsillitis, with a mandatory 10-day course to prevent rheumatic fever and ensure bacterial eradication. 1
First-Line Antibiotic Selection
- Penicillin V (phenoxymethylpenicillin) remains the gold standard with five decades of proven efficacy and zero documented resistance development by Group A streptococci 1
- Penicillin V dosing: 250 mg four times daily OR 500 mg twice daily for 10 days in adults; 250 mg two to three times daily for 10 days in children 1
- Amoxicillin is preferred in younger children due to better taste and suspension availability, dosed at 50 mg/kg once daily (maximum 1,000 mg) for 10 days in pediatrics, or 250 mg four times daily OR 500 mg twice daily for 10 days in adults 1
- Intramuscular penicillin G benzathine is a single-dose alternative: 600,000 units for patients <27 kg, 1,200,000 units for patients ≥27 kg 1
Second-Line Options for Penicillin Allergy
- Cephalexin is the preferred second-choice antibiotic based on lower relapse rates, good tolerability, and narrow spectrum, dosed at 20 mg/kg per dose twice daily (maximum 500 mg per dose) for 10 days 1
- Clarithromycin should only be used when severe penicillin allergy exists, dosed at 7.5 mg/kg per dose twice daily (maximum 250 mg per dose) for 10 days, but its effectiveness is significantly compromised in areas with high macrolide resistance 1
- Clindamycin is an alternative for severe allergy, dosed at 7 mg/kg per dose three times daily (maximum 300 mg per dose) for 10 days 1
Critical Treatment Duration Requirements
- The 10-day treatment course is non-negotiable for penicillin, amoxicillin, and clarithromycin to prevent rheumatic fever (risk reduction RR 0.27) and suppurative complications including peritonsillar abscess (RR 0.15) and acute otitis media (RR 0.30) 1
- Only the 10-day antibiotic regimen has proven effective in preventing rheumatic fever and glomerulonephritic diseases, despite short-term courses showing comparable symptom reduction 2
- Shorter courses of antibiotics (3-5 days) may achieve similar primary healing but lack evidence for preventing serious sequelae 2
Azithromycin: Limited Role
- Azithromycin is NOT a first-line agent and should only be considered as an alternative to first-line therapy in individuals who cannot use first-line options 3
- The FDA label explicitly states: "Penicillin by the intramuscular route is the usual drug of choice in the treatment of Streptococcus pyogenes infection and the prophylaxis of rheumatic fever" 3
- Azithromycin dosing for pharyngitis/tonsillitis: 12 mg/kg once daily for 5 days in children 3
- Critical limitation: Some strains are resistant to azithromycin, and susceptibility testing should be performed when using this agent 3
- Data establishing efficacy of azithromycin in subsequent prevention of rheumatic fever are NOT available 3
Watchful Waiting Strategy
- Consider delayed prescribing (>48 hours after initial consultation) in less severe presentations, as this approach shows no significant differences in complication rates compared to immediate treatment 1
- Antibiotics provide modest benefit but must be weighed against side effects, antimicrobial resistance, and costs 1
Key Clinical Pitfalls to Avoid
- Never use routine skin testing for penicillin allergy before first exposure—it is unnecessary 1
- Do not rely on rapid antigen testing alone—it has very low sensitivity for bacterial tonsillitis 2
- Avoid microbiological screening in asymptomatic children—10% of healthy children carry Streptococcus pyogenes without clinical signs, and decolonization is not necessary 2
- Be aware of geographic macrolide resistance patterns—local resistance data should guide macrolide use 1
- Penicillin bacteriologic failure rates have increased from 2-10% historically to approximately 30%, primarily due to non-compliance with the 10-day regimen, reexposure to infected contacts, and copathogenicity with beta-lactamase producing bacteria 4