What is the first choice antibiotic for streptococcal angina?

First Choice Antibiotics for Streptococcal Angina (Pharyngitis)

Penicillin V or amoxicillin is the first-line treatment for streptococcal angina (pharyngitis), administered for a full 10-day course. 1

First-Line Treatment Options

• Penicillin V: 500 mg orally 2-3 times daily for 10 days (adults)
• Amoxicillin: 50 mg/kg once daily (maximum 1000 mg) for 10 days

These recommendations are supported by the Infectious Diseases Society of America (IDSA) and the American Academy of Family Physicians with moderate to strong evidence 1. Penicillin has remained the gold standard treatment for streptococcal pharyngitis for decades due to its proven efficacy, safety profile, narrow spectrum, and low cost.

Why a Full 10-Day Course is Critical

A complete 10-day course of antibiotics is essential to:

• Prevent rheumatic fever (a serious complication)
• Ensure complete eradication of Group A Streptococcus
• Reduce risk of treatment failure

Even if symptoms resolve earlier, the full course must be completed to prevent complications 1.

Alternative Options for Penicillin-Allergic Patients

For patients with penicillin allergy, treatment depends on the type of allergy:

Non-Anaphylactic Allergy:

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

Immediate Hypersensitivity or Anaphylactic Allergy:

• Clindamycin: 7 mg/kg three times daily (maximum 300 mg per dose) for 10 days
• Azithromycin: 12 mg/kg once daily (maximum 500 mg) for 5 days
• Clarithromycin: 7.5 mg/kg twice daily (maximum 250 mg per dose) for 10 days 2, 1

Important Caution: Resistance of Group A Streptococcus to macrolides (azithromycin, clarithromycin) is well-documented and varies geographically 2. The FDA label for azithromycin specifically notes that susceptibility testing should be performed when using it for streptococcal infections 3.

Treatment Algorithm

1. Confirm diagnosis using Centor criteria and rapid antigen detection test (RADT) or throat culture

2. Select appropriate antibiotic:

   • No penicillin allergy → Penicillin V or amoxicillin for 10 days
   • Non-anaphylactic penicillin allergy → Cephalosporins for 10 days
   • Anaphylactic penicillin allergy → Clindamycin, azithromycin, or clarithromycin

3. Complete full course of antibiotics (10 days for all except azithromycin which is 5 days)

4. Provide symptomatic relief with NSAIDs, acetaminophen, warm salt water gargles

Common Pitfalls to Avoid

1. Incomplete treatment course: Failure to complete the full 10-day course increases risk of rheumatic fever and treatment failure
2. Using macrolides as first-line: Due to increasing resistance patterns, macrolides should be reserved for penicillin-allergic patients
3. Not considering local resistance patterns: Geographic variations in resistance should inform antibiotic selection
4. Treating viral pharyngitis with antibiotics: Ensure proper diagnosis before initiating antibiotics

Special Considerations

• Patients are considered non-contagious after 24 hours of appropriate antibiotic therapy 1
• For recurrent infections or chronic carriers, alternative regimens including clindamycin or combination therapy with rifampin may be needed 2
• Data establishing efficacy of azithromycin in preventing rheumatic fever are not available 3