What is the recommended dose of antibiotics, such as penicillin (Penicillin) or amoxicillin (Amoxicillin), for a patient with bacterial tonsillitis?

Antibiotic Dosing for Bacterial Tonsillitis

For bacterial tonsillitis, prescribe either penicillin V (250 mg twice or three times daily for children, 500 mg twice daily for adolescents/adults) or amoxicillin (50 mg/kg once daily, maximum 1000 mg, or 25 mg/kg twice daily, maximum 500 mg per dose) for 10 days. 1

First-Line Treatment Selection

Penicillin V and amoxicillin are the preferred first-line antibiotics for Group A streptococcal tonsillitis based on their efficacy, safety profile, narrow spectrum, and low cost. 1 The choice between these two agents is largely a matter of convenience:

Penicillin V Dosing

• Children: 250 mg twice or three times daily for 10 days 1
• Adolescents and adults: 250 mg four times daily OR 500 mg twice daily for 10 days 1

Amoxicillin Dosing (Equally Effective Alternative)

• Pediatric: 50 mg/kg once daily (maximum 1000 mg) OR 25 mg/kg twice daily (maximum 500 mg per dose) for 10 days 1
• Adults: 500 mg twice daily for 10 days 1

Amoxicillin offers the advantage of once or twice daily dosing, which may improve adherence compared to penicillin V's three to four times daily regimen. 1 Clinical cure rates are equivalent between amoxicillin (86%) and penicillin (92%) in children with streptococcal tonsillopharyngitis. 1

Intramuscular Option

• Benzathine penicillin G: Single dose of 600,000 units for patients <27 kg or 1,200,000 units for patients ≥27 kg 1
• This option is particularly useful when adherence to oral therapy is a concern 1

Duration of Therapy

The full 10-day course must be completed even if symptoms resolve earlier, as this duration is necessary to prevent acute rheumatic fever, suppress recurrence, and ensure adequate bacterial eradication. 1, 2 While shorter courses (3-7 days) have been studied, 7-day penicillin treatment was superior to 3-day treatment in resolving symptoms, and 10-day courses remain the standard to maximize bacterial eradication. 1

Penicillin Allergy Alternatives

For patients with documented penicillin allergy, the choice depends on the type of reaction:

Non-Type I Hypersensitivity

• Cephalexin: 20 mg/kg/dose 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

Type I (Immediate) Hypersensitivity

• Clindamycin: 7 mg/kg/dose three times daily (maximum 300 mg per dose) for 10 days 1
• Azithromycin: 12 mg/kg once daily (maximum 500 mg) for 5 days 1
• Clarithromycin: 7.5 mg/kg/dose twice daily (maximum 250 mg per dose) for 10 days 1

Important caveat: Macrolides (azithromycin, clarithromycin, erythromycin) have bacteriologic failure rates of 20-25% due to geographic and temporal variations in resistance. 1, 2 They should be used cautiously and only when beta-lactams are contraindicated.

When NOT to Use Amoxicillin-Clavulanate (Augmentin)

Augmentin is NOT recommended as first-line therapy for uncomplicated streptococcal tonsillitis. 2 The addition of clavulanate does not improve outcomes and unnecessarily increases cost and gastrointestinal side effects. 2

Reserve Augmentin For:

• Treatment failures after initial amoxicillin or penicillin therapy 2
• Chronic Group A Streptococcus carriers who have failed first-line therapy 1, 2

Augmentin Dosing (When Indicated)

• Pediatric: 40 mg amoxicillin/kg/day divided into three doses (maximum 2000 mg amoxicillin per day) for 10 days 1, 2

Treatment Failure Management

Reassess the patient after 48-72 hours if symptoms worsen or fail to improve. 2 Treatment failure may occur in approximately 30% of cases due to:

• Non-adherence to the 10-day regimen 3
• Reexposure to infected contacts 3
• Co-pathogenic bacteria producing beta-lactamase 3

For Treatment Failures:

Consider switching to agents with broader coverage or beta-lactamase stability, such as cephalosporins or amoxicillin-clavulanate. 2 Cephalosporins demonstrate superior bacterial eradication compared to penicillin (OR 1.47,95% CI 1.06-2.03), though clinical differences are modest. 1

Critical Clinical Pitfalls

• Do not prescribe shorter courses than 10 days for routine cases, as this increases risk of rheumatic fever despite modest improvements in compliance 1
• Avoid empiric use of broad-spectrum agents (cephalosporins, fluoroquinolones) as first-line therapy, as this promotes resistance without improving outcomes 1
• Do not confuse chronic carriers with acute infection: Carriers do not require treatment unless specific circumstances exist (outbreak situations, family history of rheumatic fever) 1
• Verify true penicillin allergy before using alternatives, as many reported allergies are not Type I hypersensitivity reactions and cephalosporins may be safely used 1, 2