What can you give someone who is penicillin (pcn) allergic for streptococcal pharyngitis (strep)?

Treatment of Streptococcal Pharyngitis in Penicillin-Allergic Patients

For penicillin-allergic patients with strep throat, first-generation cephalosporins (cephalexin or cefadroxil) are the preferred first-line alternatives if the allergy is non-immediate, while clindamycin or azithromycin should be used for patients with immediate/anaphylactic penicillin reactions. 1

Treatment Algorithm Based on Allergy Type

Non-Immediate Penicillin Allergy (e.g., rash, delayed reaction)

• First-generation cephalosporins are strongly recommended with high-quality evidence 2, 1:
  • Cephalexin: 20 mg/kg per dose twice daily (maximum 500 mg per dose) for 10 days 2, 1
  • Cefadroxil: 30 mg/kg once daily (maximum 1 g) for 10 days 2, 1
• These agents have demonstrated high success rates in eradicating streptococci and are the preferred choice when immediate hypersensitivity is not present 1, 3

Immediate/Anaphylactic Penicillin Allergy (e.g., anaphylaxis, angioedema, severe urticaria)

• Avoid all cephalosporins due to up to 10% cross-reactivity risk in patients with immediate hypersensitivity 2, 1, 3
• Clindamycin is the preferred alternative: 7 mg/kg per dose three times daily (maximum 300 mg per dose) for 10 days 2, 1
  • Strong, moderate-quality evidence supporting efficacy 2
  • Particularly effective even in chronic carriers 1
  • Resistance rates in the United States are approximately 1% 1
• Macrolide alternatives (if clindamycin unavailable or not tolerated):
  • Azithromycin: 12 mg/kg once daily (maximum 500 mg) for 5 days only 2, 1, 4
  • Clarithromycin: 7.5 mg/kg per dose twice daily (maximum 250 mg per dose) for 10 days 2, 1

Critical Duration Considerations

• All antibiotics require a full 10-day course to achieve maximal pharyngeal eradication of Group A Streptococcus 1, 3
• Azithromycin is the only exception, requiring only 5 days due to its prolonged tissue half-life 2, 1, 4
• Prescribing shorter courses (except azithromycin) leads to treatment failure and increased risk of complications including rheumatic fever 1

Important Resistance Patterns and Caveats

• Macrolide resistance among Group A Streptococcus in the United States is approximately 5-8% but varies geographically and temporally 2, 1
• Always consider local resistance patterns when prescribing azithromycin or clarithromycin 1, 3
• Clindamycin resistance remains low at approximately 1% in the United States, making it a reliable choice 1
• Susceptibility testing should be performed when treating with azithromycin, as some strains are resistant 4

Common Pitfalls to Avoid

• Do not assume all penicillin-allergic patients cannot receive cephalosporins - only those with immediate/anaphylactic reactions should avoid them 1, 3
• Do not use trimethoprim-sulfamethoxazole (Bactrim) for strep throat due to high resistance rates (50%) and lack of efficacy against Group A Streptococcus 1
• Do not prescribe azithromycin for less than 5 days or other antibiotics for less than 10 days, as this compromises eradication rates 1, 3
• Do not rely on azithromycin to treat or exclude syphilis in patients with sexually-transmitted infections 4

Adjunctive Therapy

• Acetaminophen or NSAIDs are recommended for moderate to severe symptoms or high fever 1
• Avoid aspirin in children due to risk of Reye syndrome 1
• Corticosteroids are not recommended as adjunctive therapy 1

Special Considerations for Treatment Failures

• For patients with recurrent streptococcal pharyngitis or chronic carriers, clindamycin may be particularly effective due to its superior ability to eradicate the organism 1, 3
• Chronic carriers generally do not require antimicrobial therapy unless specific circumstances exist (outbreak situations, history of rheumatic fever, excessive anxiety, or planned tonsillectomy) 2