What antibiotic is recommended for strep throat in a patient with a penicillin allergy?

Antibiotic Treatment for Strep Throat in Patients with Penicillin Allergy

For patients with penicillin allergy who have strep throat, a 10-day course of a first-generation cephalosporin (if no history of immediate hypersensitivity) or clindamycin (if anaphylactic penicillin allergy) is recommended as first-line treatment. 1

Treatment Algorithm Based on Type of Penicillin Allergy

For Non-Anaphylactic Penicillin Allergy:

• First-generation cephalosporins are the preferred treatment option 1:
  • Cephalexin: 20 mg/kg/dose twice daily (maximum 500 mg/dose) for 10 days 1
  • Cefadroxil: 30 mg/kg once daily (maximum 1 g) for 10 days 1

For Immediate/Anaphylactic Penicillin Allergy:

• Clindamycin: 7 mg/kg/dose three times daily (maximum 300 mg/dose) for 10 days 1, 2, 3
• Macrolide options (if clindamycin cannot be used):
  • Clarithromycin: 7.5 mg/kg/dose twice daily (maximum 250 mg/dose) for 10 days 1
  • Azithromycin: 12 mg/kg once daily (maximum 500 mg) for 5 days 1, 4

Efficacy and Evidence Quality

• First-generation cephalosporins have strong, high-quality evidence for efficacy in non-anaphylactic penicillin-allergic patients 1
• Clindamycin has strong, moderate-quality evidence with approximately 1% resistance among Group A Streptococcus isolates in the United States 1, 2
• Macrolides have strong, moderate-quality evidence but carry concerns about resistance (5-8% in the US) 1, 5

Important Considerations and Potential Pitfalls

• Up to 10% of patients with immediate hypersensitivity to penicillin may have cross-reactivity with cephalosporins, so these should be avoided in patients with anaphylactic-type reactions to penicillin 1, 2
• Most antibiotics require a full 10-day course to achieve maximal pharyngeal eradication of Group A Streptococcus, with azithromycin being the exception (5-day course) 1, 5
• Erythromycin is associated with substantially higher rates of gastrointestinal side effects compared to other macrolides 1, 6
• Macrolide resistance varies geographically and temporally, which may impact treatment success 1, 5
• Clindamycin is particularly effective for eradicating streptococci, even in chronic carriers 5, 2

Adjunctive Therapy

• Acetaminophen or NSAIDs can be used for moderate to severe symptoms or high fever 1, 5
• Aspirin should be avoided in children due to the risk of Reye syndrome 1
• Corticosteroids are not recommended as adjunctive therapy 1

Follow-Up Recommendations

• Routine post-treatment throat cultures are not recommended for asymptomatic patients who have completed therapy 1, 2
• Follow-up testing should only be considered in special circumstances, such as patients with a history of rheumatic fever 5, 2

By following this treatment algorithm based on the type of penicillin allergy, clinicians can effectively treat strep throat while minimizing the risk of allergic reactions and treatment failure.