What is the first-line treatment for impetigo in a patient with a history of allergy to amoxicillin (amoxicillin)

First-Line Treatment for Impetigo in Patients with Amoxicillin Allergy

For patients with a history of amoxicillin allergy, the first-line treatment for impetigo is topical mupirocin or oral cephalosporins such as cefdinir, cefuroxime, or cefpodoxime. 1

Treatment Options Based on Allergy History

Topical Antibiotics

• Topical mupirocin is an excellent first-line option for patients with limited impetigo lesions and amoxicillin allergy 2, 3
• Topical antibiotics show better cure rates than placebo (pooled odds ratio 6.49) and have fewer systemic side effects than oral antibiotics 3
• Topical fusidic acid is an alternative with similar efficacy to mupirocin 3

Oral Antibiotics for Extensive Disease

For Non-Anaphylactic Amoxicillin Allergy:

• Cefdinir (14 mg/kg/day in 1 or 2 doses) is recommended as first-line oral therapy 1
• Cefuroxime (30 mg/kg/day in 2 divided doses) is an effective alternative 1
• Cefpodoxime (10 mg/kg/day in 2 divided doses) can also be used 1

For Anaphylactic Amoxicillin Allergy:

• Clindamycin (30-40 mg/kg/day in 3 divided doses) is recommended for patients with severe penicillin allergy 1
• Macrolides (erythromycin, azithromycin, clarithromycin) can be considered, though resistance rates to erythromycin are rising 2

Decision Algorithm Based on Disease Extent and Allergy Type

1. Limited disease (few lesions):

   • Topical mupirocin or fusidic acid applied to affected areas 3 times daily for 5-7 days 2, 3

2. Extensive disease (multiple lesions) with non-anaphylactic amoxicillin allergy:

   • Cephalosporins are highly unlikely to cross-react with penicillin allergy based on their distinct chemical structures 1
   • Cefdinir, cefuroxime, or cefpodoxime are recommended options 1

3. Extensive disease with history of anaphylaxis to amoxicillin:

   • Avoid cephalosporins if the patient has a history of anaphylaxis, angioedema, or urticaria after treatment with any form of penicillin 1
   • Use clindamycin or macrolides instead 1, 2

Important Clinical Considerations

• Topical antibiotics may be superior to oral antibiotics for limited disease and have fewer side effects 2, 3
• Oral antibiotics should be reserved for patients with extensive disease or when topical therapy is impractical 2, 4
• Resistance patterns against antibiotics change and should be taken into account in the choice of therapy 3, 5
• Penicillin V is seldom effective for impetigo treatment 2
• Treatment helps relieve discomfort, improve cosmetic appearance, and prevent spread of organisms that may cause other illnesses 2

Cross-Reactivity Considerations

• Patients with non-severe penicillin allergy histories can safely receive cephalosporins with dissimilar R1 side chains 1
• The risk of cross-reactivity between penicillins and cephalosporins is very low (<5%) 1
• For patients with a history of anaphylaxis to penicillins, avoid cephalosporins and use alternative agents like clindamycin 1

Duration of Treatment

• Treatment typically continues for 7-10 days or until 48 hours after lesions have resolved 2
• Reassess if no improvement is seen within 48-72 hours, as this may indicate resistance or misdiagnosis 1