What is the treatment for a sore swollen tonsil suspected to be of bacterial origin?

Treatment of Suspected Bacterial Tonsillitis

For suspected bacterial tonsillitis, penicillin V (250 mg twice or three times daily for 10 days in children; 250 mg four times daily or 500 mg twice daily for 10 days in adolescents/adults) is the first-line treatment, but only after confirming Group A Streptococcus (GAS) infection through rapid antigen detection testing (RADT) or throat culture. 1, 2

Diagnostic Confirmation Before Treatment

• Never prescribe antibiotics without microbiological confirmation of GAS infection through RADT and/or throat culture 2, 3
• Use the Centor/McIsaac criteria to guide testing: fever, tonsillar exudate, tender anterior cervical lymphadenopathy, and absence of cough 2
• Patients with 0-2 Centor criteria should not receive antibiotics, as viral etiology is most likely 4, 2
• Patients with 3-4 Centor criteria warrant testing and consideration of antibiotics only if GAS-positive 4, 2
• If RADT is performed, throat culture is not necessary after a negative RADT for diagnosis of GAS 4

First-Line Antibiotic Treatment (After Confirmed GAS)

Penicillin V remains the gold standard due to proven efficacy, safety, narrow spectrum, and low cost 1:

• Children: 250 mg twice or three times daily for 10 days 4, 1
• Adolescents/Adults: 250 mg four times daily OR 500 mg twice daily for 10 days 4, 1

Alternative first-line option - Amoxicillin 1, 2:

• Children: 50 mg/kg once daily (maximum 1000 mg) OR 25 mg/kg twice daily (maximum 500 mg per dose) for 10 days 1, 2
• More convenient dosing than penicillin V, with comparable efficacy 5

Single-dose option - Benzathine penicillin G (intramuscular) 1:

• 600,000 U for patients <27 kg
• 1,200,000 U for patients ≥27 kg
• Useful for compliance concerns

Treatment Duration: The 10-Day Rule

The standard 10-day course is critical and non-negotiable for penicillin and amoxicillin 4, 2, 6:

• Maximizes bacterial eradication and prevents complications like rheumatic fever 2, 6
• Short courses (5 days) of standard-dose penicillin are less effective for GAS eradication and should be avoided 4, 6
• One study showed 7-day penicillin was superior to 3-day treatment in resolving symptoms 4

Treatment for Penicillin-Allergic Patients

For non-anaphylactic penicillin allergy - First-generation cephalosporins 1, 2:

• 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
• Avoid in patients with immediate-type hypersensitivity to penicillin 1

For anaphylactic penicillin allergy 1, 2:

• 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 1, 3
  • Note: Increasing GAS resistance to macrolides is a concern 1, 3
  • Susceptibility testing should be performed when using azithromycin 3
  • Data establishing efficacy in preventing rheumatic fever are not available 3
• Clarithromycin: 7.5 mg/kg twice daily (maximum 250 mg per dose) for 10 days 1, 7

Symptomatic Treatment (For All Patients)

Provide symptomatic relief regardless of antibiotic use 4, 2, 6:

• Ibuprofen or paracetamol (acetaminophen) for pain and fever 4, 2
• This is a Grade A-1 recommendation from European guidelines 4

Management of Treatment Failure or Recurrent Tonsillitis

If symptoms return within 2 weeks of completing therapy, consider 2, 6:

• Clindamycin: 20-30 mg/kg/day in 3 divided doses (maximum 300 mg/dose) for 10 days 2, 6
• Amoxicillin-clavulanate: 40 mg/kg/day (amoxicillin component) in 3 divided doses for 10 days 2, 6, 8
  • This combination is effective against beta-lactamase producing bacteria that may contribute to treatment failure 8
• Consider the possibility of chronic GAS carriage with intercurrent viral infections rather than true recurrent bacterial infection 6

Critical Pitfalls to Avoid

• Never prescribe antibiotics without confirming GAS infection through testing 2, 3
• Never use courses shorter than 10 days for standard penicillin or amoxicillin - this increases treatment failure risk 4, 2, 6
• Do not perform follow-up throat cultures on asymptomatic patients who completed appropriate therapy 2, 6
• Do not use broad-spectrum antibiotics when narrow-spectrum penicillins are effective for confirmed GAS 2, 6
• Antibiotics should not be used in patients with 0-2 Centor criteria to relieve symptoms 4
• Modest benefits of antibiotics in patients with 3-4 Centor criteria must be weighed against side effects, effects on microbiota, increased antibacterial resistance, medicalization, and costs 4

Special Considerations

• Penicillin penetrates to tonsillar surface fluid only in the presence of inflammation with fluid exudation, which explains why it works in acute tonsillitis 9
• Cephalosporins have demonstrated higher clinical cure rates than penicillin in some meta-analyses, though the clinical significance remains debated 4, 1
• Prevention of suppurative complications is not a specific indication for antibiotic therapy in sore throat 4
• Tonsillectomy is not recommended solely to reduce the frequency of GAS pharyngitis 6