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

Treatment Options for Streptococcal Infections in Patients with Penicillin Allergy

For patients with streptococcal infections who have penicillin allergies, clindamycin is the recommended first-line alternative treatment due to its high efficacy and low resistance rates. 1

First-Line Alternatives Based on Allergy Severity

For Patients with Non-Immediate (Non-Anaphylactic) Penicillin Allergy:

• First-generation cephalosporins are recommended as they have strong evidence supporting their efficacy 2
  • Cephalexin: 20 mg/kg per dose twice daily (maximum = 500 mg per dose) for 10 days 2
  • Cefadroxil: 30 mg/kg once daily (maximum = 1 g) for 10 days 2
• These should be avoided in patients with immediate (anaphylactic-type) hypersensitivity to penicillin, as up to 10% may have cross-reactivity 2

For Patients with Severe/Immediate Penicillin Allergy:

• Clindamycin: 7 mg/kg per dose three times daily (maximum = 300 mg per dose) for 10 days 2, 1
  • Clindamycin has approximately 1% resistance rate among Group A Streptococcus in the United States 2, 1
• Macrolides are alternative options but carry higher resistance concerns:
  • Azithromycin: 12 mg/kg once daily (maximum = 500 mg) for 5 days 2, 3
  • Clarithromycin: 7.5 mg/kg per dose twice daily (maximum = 250 mg per dose) for 10 days 2
  • Erythromycin: 20-40 mg/kg/day divided 2-3 times daily for 10 days 1

Duration of Therapy

• A full 10-day course is required for most antibiotics to achieve maximal pharyngeal eradication of Group A Streptococcus 2, 1
• Azithromycin is the exception, requiring only a 5-day course due to its prolonged tissue half-life 1, 4

Efficacy Considerations

• Macrolide resistance rates among pharyngeal isolates in the United States have been reported around 5-8% in recent years 2
• Some studies suggest that 10 days of clarithromycin may be more effective in eradicating Group A Streptococcus than 5 days of azithromycin 2
• Clindamycin has demonstrated high efficacy in eradicating streptococci, even in chronic carriers 2

Adjunctive Therapy

• Consider acetaminophen or NSAIDs for moderate to severe symptoms or high fever 2
• Avoid aspirin in children due to the risk of Reye syndrome 2
• Corticosteroids are not recommended as adjunctive therapy 2

Important Considerations and Pitfalls

• Always verify the nature of the penicillin allergy - many patients with vague histories of penicillin allergy can safely receive cephalosporins 5
• For patients with a convincing history of immediate-type penicillin allergy, avoid cephalosporins and use clindamycin or macrolides 5
• Macrolide resistance varies geographically - be aware of local resistance patterns 2, 1
• Do not routinely perform post-treatment throat cultures for asymptomatic patients who have completed therapy 2
• For patients with recurrent streptococcal pharyngitis, clindamycin may be particularly effective due to its ability to eradicate the organism in chronic carriers 2

Special Populations

• For patients unlikely to complete a full 10-day course of oral therapy, consider alternative dosing strategies or closer follow-up 2
• For pregnant patients with penicillin allergy, clindamycin is generally considered safe 1

Remember that while penicillin remains the drug of choice for non-allergic patients due to its proven efficacy, safety, narrow spectrum, and low cost, these alternative regimens provide effective options for those with penicillin allergies 2, 6.