Penicillin allergy that persisted after 66 years: case report

Area of Science:

• Allergy and Immunology
• Clinical Pharmacy
• Infectious Diseases

Background:

• Penicillin allergy is frequently reported but true allergies are rare (<1%).
• Antimicrobial stewardship utilizes pharmacist-led protocols for penicillin allergy rechallenge.
• Published data support successful penicillin rechallenge and desensitization.

Observation:

• A 74-year-old woman with a childhood penicillin allergy history was rechallenged with amoxicillin/clavulanate.
• The rechallenge was for a urinary tract infection, with amoxicillin/clavulanate identified as the optimal empirical treatment.
• A low likelihood of reactivity was anticipated due to the allergy's distant history.

Findings:

• The patient developed an allergic reaction after a single oral dose of amoxicillin/clavulanate 875/125 mg.
• This occurred despite the allergy being documented over 60 years prior.

Implications:

• This case highlights the potential for unexpected allergic reactions even after long-standing reported penicillin allergies.
• It underscores the need for caution and careful consideration during antibiotic rechallenge protocols.
• Further investigation into the persistence and clinical significance of childhood penicillin allergies is warranted.