What are the most common antibiotics used to treat bacterial tonsillitis?

Most Common Antibiotics for Bacterial Tonsillitis

Penicillin remains the first-line treatment for bacterial tonsillitis caused by Group A Streptococcus, with amoxicillin often used in younger children due to taste considerations, while erythromycin is the preferred alternative for penicillin-allergic patients. 1

First-Line Treatment Options

For Patients Without Penicillin Allergy:

• Penicillin V

  • Children: 250 mg 2-3 times daily for 10 days
  • Adolescents/Adults: 250 mg 4 times daily or 500 mg twice daily for 10 days 1
  • Advantages: Proven efficacy, safety, narrow spectrum, low cost, and no resistance development in Group A streptococci over decades 1

• Amoxicillin

  • 50 mg/kg once daily (maximum 1000 mg) or 25 mg/kg twice daily (maximum 500 mg per dose) for 10 days 1, 2
  • Often preferred for younger children due to better taste and availability as syrup/suspension 1
  • Caution: Poor first choice in older children due to risk of severe rash in patients with concurrent Epstein-Barr virus infection 1

• Benzathine Penicillin G (intramuscular)

  • <27 kg: 600,000 units as single dose
  • ≥27 kg: 1,200,000 units as single dose 1
  • Particularly useful when compliance with oral therapy is questionable 1

For Patients With Penicillin Allergy:

• Erythromycin

  • 30-50 mg/kg/day in equally divided doses for 10 days (not exceeding 4g/day) 3
  • Adults: 250 mg 4 times daily or 500 mg every 12 hours 3

• Other Macrolides

  • Azithromycin: 12 mg/kg once daily (maximum 500 mg) for 5 days 1, 4
  • Clarithromycin: 7.5 mg/kg twice daily (maximum 250 mg per dose) for 10 days 1
  • Note: Resistance to macrolides varies geographically and should be considered 1

• Cephalosporins (for non-immediate penicillin hypersensitivity)

  • Cephalexin: 20 mg/kg twice daily (maximum 500 mg per dose) for 10 days
  • Cefadroxil: 30 mg/kg once daily (maximum 1g) for 10 days 1

• Clindamycin

  • 7 mg/kg 3 times daily (maximum 300 mg per dose) for 10 days 1
  • Particularly effective for recurrent cases or treatment failures 1, 5

Treatment Duration Considerations

The standard recommendation is a full 10-day course of antibiotics to achieve maximal pharyngeal eradication of Group A streptococci 1. While shorter courses (≤5 days) of newer agents have been studied, definitive evidence supporting these shorter regimens is lacking, and they cannot be routinely recommended 1.

Management of Treatment Failures

For patients who experience recurrent episodes of Group A streptococcal pharyngitis after completing appropriate therapy:

1. Single recurrence: Retreat with the same antibiotic used initially 1

2. Multiple recurrences: Consider:

   • Clindamycin: 20-30 mg/kg/day in 2-4 divided doses for 10 days (adults: 600 mg/day)
   • Amoxicillin/clavulanate: 40 mg/kg/day in 3 divided doses for 10 days 1
   • Benzathine penicillin G (intramuscular) if compliance with oral therapy is questionable 1

Clinical Pearls and Pitfalls

• Beta-lactamase-producing bacteria may "shield" Group A streptococci by inactivating penicillin in some treatment failures 6

• Compliance issues are common with 10-day regimens; ensure patients understand the importance of completing the full course even if symptoms improve 1

• Avoid amoxicillin in older children with suspected Epstein-Barr virus co-infection due to risk of severe rash 1

• Do not perform routine follow-up cultures after completion of therapy unless symptoms persist 1

• Tonsillectomy should not be performed solely to reduce frequency of Group A streptococcal pharyngitis 1

• Carriers (asymptomatic individuals with positive cultures) generally do not require antimicrobial therapy 1