What is the recommended treatment for streptococcal (strep) infection in a patient with a penicillin allergy?

Treatment for Streptococcal Infection in Patients with Penicillin Allergy

For patients with penicillin allergy, clindamycin is the preferred antibiotic for streptococcal infections, with macrolides (azithromycin, clarithromycin, erythromycin) as reasonable alternatives despite increasing resistance rates. 1

Assessment of Penicillin Allergy Severity

The approach to treating streptococcal infections in penicillin-allergic patients depends on the severity of the allergic reaction:

• Severe penicillin allergy (history of anaphylaxis, angioedema, respiratory distress, or urticaria):

  • Avoid penicillins, ampicillin, and cephalosporins
  • Use alternative antibiotics as outlined below

• Non-severe penicillin allergy (without history of severe reactions):

  • Cephalosporins may be used safely
  • Cefazolin is preferred for its effective coverage 2

First-Line Treatment Options

1. Clindamycin

• Dosage: 7 mg/kg three times daily (maximum 300 mg per dose) for 10 days 1
• Advantages: Excellent coverage against Group A Streptococcus with low resistance rates
• Recommended by: American Heart Association for penicillin-allergic patients 1

2. Macrolides (for patients unable to take clindamycin)

• Azithromycin:

  • Dosage: 12 mg/kg once daily (maximum 500 mg) for 5 days 1
  • Note: Higher failure rates compared to 10-day regimens 3

• Erythromycin:

  • Dosage for adults: 250 mg four times daily or 500 mg twice daily for 10 days 4
  • Dosage for children: 30-50 mg/kg/day in divided doses for 10 days 4

• Clarithromycin:

  • More effective than 5-day azithromycin in eradicating Group A Streptococcus (91% vs 82%) 3
  • 10-day course recommended

Special Considerations

For Group B Streptococcal Prophylaxis During Labor

For pregnant women with penicillin allergy and risk of anaphylaxis:

• If GBS isolate is susceptible to clindamycin and erythromycin: Use clindamycin 900 mg IV every 8 hours until delivery
• If susceptibility unknown or resistant: Use vancomycin 1 g IV every 12 hours until delivery 2

Treatment Failures

• Penicillin treatment failures have increased to approximately 30% in recent years 5
• Consider switching to a cephalosporin (if non-severe penicillin allergy) or clindamycin (if severe allergy) for treatment failures with macrolides

Monitoring and Follow-up

• Routine post-treatment throat cultures are not recommended 1
• For symptom management, NSAIDs (e.g., ibuprofen 400 mg every 6-8 hours) are preferred for pain and fever 1

Important Caveats

• Macrolide resistance is increasing, potentially limiting effectiveness 1
• When treating streptococcal pharyngitis, a full 10-day course is recommended to prevent rheumatic fever, even if symptoms resolve earlier
• For patients with both penicillin and cephalosporin allergies, clindamycin is clearly the preferred option over macrolides due to better efficacy and lower resistance rates

Remember that complete eradication of Group A Streptococcus is essential to prevent complications such as rheumatic fever, particularly in pharyngitis/tonsillitis cases.