Management of Tonsillitis Not Responding to Amoxicillin
Switch to high-dose amoxicillin-clavulanate (90 mg/kg/day of amoxicillin component, not to exceed 2g every 12 hours) as the next step for tonsillitis failing to respond to amoxicillin after several days. 1
Rationale for Antibiotic Switch
The failure of amoxicillin in tonsillitis is commonly due to β-lactamase-producing bacteria (present in 85% of tonsillar cultures) that inactivate penicillins. 2 When patients show little or no symptomatic improvement after 3-5 days of amoxicillin therapy, switching to an antibiotic that covers resistant bacteria is indicated. 1
Specific Antibiotic Recommendation
High-dose amoxicillin-clavulanate is the reference antibiotic for amoxicillin failure, providing coverage against β-lactamase-producing organisms including Haemophilus influenzae and Moraxella catarrhalis, while maintaining enhanced activity against drug-resistant Streptococcus pneumoniae and Group A streptococci. 1
The dosing should be 90 mg/kg/day of the amoxicillin component with 6.4 mg/kg/day of clavulanate, not to exceed 2g every 12 hours. 1
Clinical and bacteriologic efficacy of amoxicillin-clavulanate is superior to penicillin in recurrent tonsillitis, with 100% eradication rates versus 70% with penicillin alone, and significantly fewer recurrences over one year (11% vs 58%). 2
Alternative Options for β-Lactam Allergy
If the patient has a true penicillin allergy (not just a rash):
Second or third-generation cephalosporins (cefuroxime, cefpodoxime, cefdinir) are appropriate alternatives. 1
Macrolides (azithromycin, clarithromycin) or clindamycin can be used, but have significant limitations due to resistance. 1
Clindamycin shows superior efficacy in recurrent tonsillitis compared to penicillin for both preventing future episodes and eradicating Group A streptococci. 3
Critical Pitfalls to Avoid
Do not use macrolides as first-line alternatives in areas with common macrolide resistance, as clarithromycin fails to eradicate resistant Group A streptococci in 81-86% of cases. 4
Reassess at 48-72 hours after switching antibiotics—if no improvement occurs, consider throat culture, evaluation for complications (peritonsillar abscess, retropharyngeal abscess), or alternative diagnoses. 1
Complete the full 10-14 day course of the new antibiotic to ensure complete eradication and prevent relapse. 1
When to Consider Further Evaluation
- If symptoms persist despite appropriate antibiotic switch, evaluate for:
- Infectious mononucleosis or other viral etiologies
- Peritonsillar or retropharyngeal abscess
- Non-infectious causes of pharyngitis
- Recurrent tonsillitis requiring ENT referral for possible tonsillectomy 3