What is the recommended oral antibiotic treatment for bacterial tonsillitis?

Oral Antibiotic Treatment for Bacterial Tonsillitis

Penicillin V (phenoxymethylpenicillin) administered twice or three times daily for 10 days is the first-line antibiotic treatment for confirmed bacterial tonsillitis caused by Group A Streptococcus. 1, 2, 3

Confirming Bacterial Infection Before Treatment

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

First-Line Antibiotic Regimens

Penicillin V (Preferred)

• Children: 250 mg twice or three times daily for 10 days 1, 3
• Adolescents/Adults: 250 mg four times daily OR 500 mg twice daily for 10 days 3
• Universal susceptibility of Group A Streptococcus to penicillin with no documented resistance worldwide 5
• Narrow spectrum, excellent safety profile, and lowest cost 1, 5

Amoxicillin (Acceptable Alternative)

• Children: 50 mg/kg once daily (maximum 1000 mg) OR 25 mg/kg twice daily (maximum 500 mg per dose) for 10 days 1, 3
• Adults: Standard adult dosing for 10 days 1
• Comparable efficacy to penicillin V with similar spectrum 1

Second-Line Options for Penicillin Allergy

Non-Anaphylactic Penicillin Allergy

• Cephalexin (cefalexin): 20 mg/kg twice daily (maximum 500 mg per dose) for 10 days 1, 2, 3
• Cefadroxil: 30 mg/kg once daily (maximum 1 g) for 10 days 2
• Lower relapse rates and good tolerability with narrow spectrum 1

Anaphylactic/Severe Penicillin Allergy

• Clindamycin: 7 mg/kg three times daily (maximum 300 mg per dose) for 10 days 2, 3
• Clarithromycin: Appropriate dosing for 10 days, but only in regions with low macrolide resistance 1
• Azithromycin: Alternative option but inferior bacterial eradication compared to penicillin 4

Critical Treatment Duration

• The 10-day duration is mandatory for penicillin and amoxicillin to maximize bacterial eradication and prevent rheumatic fever 1, 2, 3, 6
• Short courses (5 days) of standard-dose penicillin are less effective for GAS eradication and increase treatment failure risk 1, 2
• Only high-dose penicillin (four times daily) may be given for 5 days, though this is not standard practice 2
• The 10-day course is the only regimen proven effective in preventing rheumatic fever and glomerulonephritis 6

Management of Treatment Failure or Recurrent Tonsillitis

If Symptoms Return Within 2 Weeks

• 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
• Consider that the patient may be a chronic GAS carrier experiencing intercurrent viral infections rather than true bacterial recurrence 2

Chronic Carriers

• Up to 20% of asymptomatic school-age children may be GAS carriers during winter and spring 2
• Chronic carriers are unlikely to spread GAS and are at very low risk for complications like rheumatic fever 2
• Do not perform routine follow-up throat cultures on asymptomatic patients who completed appropriate therapy 2, 3

Symptomatic Treatment (Always Provide)

• NSAIDs (ibuprofen) or acetaminophen for pain and fever control regardless of antibiotic use 2, 3
• Warm salt water gargles for patients old enough to perform them 2

Common Pitfalls to Avoid

• Never prescribe antibiotics without microbiological confirmation of GAS infection 2, 3, 4
• Never use courses shorter than 10 days for standard penicillin or amoxicillin, as this increases treatment failure and does not prevent rheumatic fever 1, 2, 3, 6
• Never use broad-spectrum antibiotics when narrow-spectrum penicillins are effective for confirmed GAS 3
• Never perform routine follow-up cultures for asymptomatic patients who completed appropriate therapy 2, 3
• Do not use azithromycin as first-line therapy—it has inferior bacterial eradication rates and lacks data supporting rheumatic fever prevention 4
• Avoid clarithromycin in areas with high macrolide resistance (>26% of S. pyogenes isolates may be resistant) 7

When NOT to Use Amoxicillin-Clavulanate as First-Line

• Amoxicillin-clavulanate should be reserved for treatment failures or recurrent cases, not uncomplicated first presentations 5
• It causes significantly higher rates of gastrointestinal adverse events including diarrhea 5
• It is significantly more expensive than penicillin without proven superiority in uncomplicated cases 5