What is the treatment for strep throat in a patient allergic to amoxicillin (amoxicillin)

Treatment for Strep Throat in Patients Allergic to Amoxicillin

For patients with strep throat who are allergic to amoxicillin, first-line treatment options include cephalosporins (if not anaphylactically sensitive to penicillins), clindamycin, or macrolides such as clarithromycin or azithromycin for appropriate durations. 1

Diagnosis Confirmation

Before initiating treatment, confirm the diagnosis of Group A Streptococcal (GAS) pharyngitis:

• Use rapid antigen detection test (RADT) and/or throat culture
• A positive RADT is diagnostic and sufficient to begin treatment
• For children and adolescents with negative RADT, perform a backup throat culture
• For adults with negative RADT, backup culture generally not necessary due to lower incidence of GAS and rheumatic fever risk 1

Treatment Options for Amoxicillin-Allergic Patients

For Non-Anaphylactic Penicillin Allergy:

1. First-generation Cephalosporins (10 days):

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

   Note: Avoid cephalosporins in patients with immediate (anaphylactic) hypersensitivity to penicillin as up to 10% cross-reactivity exists 1

For Any Type of Penicillin Allergy (Including Anaphylaxis):

1. Clindamycin (10 days):

   • 7 mg/kg per dose three times daily (maximum = 300 mg per dose) 1
   • Resistance among GAS isolates in the US is only about 1% 1

2. Macrolides/Azalides:

   • Clarithromycin (10 days): 7.5 mg/kg per dose twice daily (maximum = 250 mg per dose) 1
   • Azithromycin (5 days): 12 mg/kg once daily (maximum = 500 mg) 1

Important Considerations

Efficacy and Resistance

• Macrolide resistance varies geographically and temporally 1
• Clindamycin has very low resistance rates in the US (approximately 1%) 1
• Cephalosporins have shown high efficacy rates against GAS pharyngitis 1

Duration of Therapy

• Most antibiotics require a full 10-day course to achieve maximal pharyngeal eradication of GAS
• Azithromycin is the exception, requiring only 5 days of treatment 1

Adjunctive Therapy

• For moderate to severe symptoms or high fever, consider analgesics/antipyretics such as acetaminophen or NSAIDs 1
• Avoid aspirin in children due to risk of Reye syndrome 1
• Corticosteroids are not recommended as adjunctive therapy 1

Treatment Algorithm

1. Assess severity of penicillin allergy:

   • If non-anaphylactic reaction → Consider cephalosporins
   • If anaphylactic reaction → Use clindamycin or macrolides

2. Consider patient factors:

   • Age (appropriate dosing)
   • Compliance history (once-daily options may improve adherence)
   • Previous treatment failures
   • Local resistance patterns

3. Select appropriate agent:

   • For patients likely to complete full course: oral antibiotics
   • For patients unlikely to complete full course: consider intramuscular benzathine penicillin G (if not allergic) 1

Common Pitfalls to Avoid

• Inadequate treatment duration: Most regimens require full 10 days of therapy (except azithromycin)
• Inappropriate cephalosporin use: Do not use in patients with immediate-type hypersensitivity to penicillin
• Unnecessary testing/treatment of asymptomatic contacts: Not routinely recommended unless specific circumstances exist 1
• Treating viral pharyngitis: Ensure proper diagnosis before initiating antibiotics
• Overlooking compliance issues: Consider once-daily regimens if adherence is a concern

Following these guidelines will help ensure effective treatment of strep throat in patients with amoxicillin allergy while minimizing complications such as rheumatic fever and suppurative sequelae.