What is the drug of choice for a patient presenting with tonsillitis?

Drug of Choice for Tonsillitis

Penicillin V remains the first-line antibiotic for confirmed bacterial (Group A Streptococcus) tonsillitis, with amoxicillin as an equally acceptable alternative, both given for 10 days. 1, 2

Diagnostic Confirmation Required Before Treatment

• Never prescribe antibiotics without microbiological confirmation of Group A Streptococcus (GAS) through rapid antigen detection testing (RADT) and/or throat culture. 2, 3
• Use the Centor/McIsaac criteria to guide testing decisions: fever, tonsillar exudate, tender anterior cervical lymphadenopathy, and absence of cough. 2, 3
• Patients with 0-2 Centor criteria should not receive antibiotics as viral etiology is most likely. 2
• Patients with 3-4 Centor criteria warrant testing and consideration of antibiotics only if GAS-positive. 2

First-Line Antibiotic Regimens

For confirmed GAS tonsillitis:

• Penicillin V: 250 mg twice or three times daily in children, or 250 mg four times daily or 500 mg twice daily in adolescents/adults for 10 days. 1, 2
• 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
• Benzathine penicillin G (single-dose option): 600,000 U for patients <27 kg, or 1,200,000 U for patients ≥27 kg. 1

The Infectious Diseases Society of America establishes penicillin as the standard therapy due to its proven efficacy in achieving clinical improvement within 24-48 hours, resolution of fever within 48 hours, and prevention of suppurative complications and rheumatic fever. 4 The 10-day duration is critical to maximize bacterial eradication and prevent complications like rheumatic fever—shorter courses increase treatment failure risk. 1, 2, 3

Treatment for Penicillin-Allergic Patients

For non-anaphylactic penicillin allergy:

• Cephalexin: 20 mg/kg twice daily (maximum 500 mg per dose) for 10 days. 1, 2
• Cefadroxil: 30 mg/kg once daily (maximum 1 g) for 10 days. 1, 2

For anaphylactic penicillin allergy:

• Clindamycin: 7 mg/kg three times daily (maximum 300 mg per dose) for 10 days. 1, 2
• Azithromycin: 12 mg/kg once daily (maximum 500 mg) for 5 days, though resistance of GAS to macrolides is a concern. 1, 5
• Clarithromycin: 7.5 mg/kg twice daily (maximum 250 mg per dose) for 10 days, with similar resistance concerns. 1

The FDA label for azithromycin demonstrates clinical success rates of 98% at Day 14 and 94% at Day 30 for pharyngitis/tonsillitis, compared to 84% and 74% respectively for penicillin V. 5 However, approximately 1% of azithromycin-susceptible S. pyogenes isolates became resistant following therapy. 5

Management of Treatment Failures and Recurrent Tonsillitis

For documented GAS tonsillitis recurring within 2 weeks of completing standard therapy:

• Clindamycin: 20-30 mg/kg/day in 3 divided doses (maximum 300 mg/dose) for 10 days. 2, 3
• Amoxicillin-clavulanate: 40 mg/kg/day (amoxicillin component) in 3 divided doses for 10 days. 2, 3

Research evidence indicates that beta-lactamase-producing bacteria (BLPB) recovered from over 75% of tonsils in patients with recurrent infection may "shield" GAS by inactivating penicillin, explaining bacteriologic failure rates up to 20%. 6 Cephalosporins, clindamycin, macrolides, and amoxicillin-clavulanate have demonstrated superior efficacy compared to penicillin in treating patients who failed previous penicillin therapy. 6

Symptomatic Treatment

• All patients should receive NSAIDs (ibuprofen) or acetaminophen for pain and fever relief, regardless of whether antibiotics are prescribed. 2, 3

Critical Pitfalls to Avoid

• Never prescribe antibiotics without microbiological confirmation of GAS. 2, 3
• Never use courses shorter than 10 days for standard penicillin or amoxicillin—this increases treatment failure risk. 2, 3
• Do not perform follow-up throat cultures on asymptomatic patients who completed appropriate therapy. 2, 3
• Do not use broad-spectrum antibiotics when narrow-spectrum penicillins are effective for confirmed GAS. 2, 3
• Do not initiate antibiotics based solely on clinical presentation without testing, as clinical differentiation between viral and bacterial tonsillitis is unreliable. 4, 3

Considerations for Tonsillectomy

The American Academy of Otolaryngology-Head and Neck Surgery recommends watchful waiting if episodes are <7 in the past year, <5 per year for 2 years, or <3 per year for 3 years. 4, 2 Tonsillectomy should only be considered when episodes meet or exceed these frequency thresholds AND each episode is documented with temperature ≥38.3°C, cervical adenopathy, tonsillar exudate, or positive GAS test. 2, 3