Comment on “The impact of penicillin skin testing on clinical practice and antimicrobial stewardship”

We read with interest the report by Rimawi et al.[1] They showed convincing evidence that with a negative penicillin skin test, a course of ‐lactam is safe 2 hours after a negative challenge. However, we advise caution in generalizing these data to the outpatient setting where resensitization is a possibility. One study showed that 4.9% of patients who had negative skin tests and drug challenges reacted on rechallenges 3 weeks later.[2]

In our center, ‐lactam allergy assessment is carried out according to European Academy of Allergy and Clinical Immunology guidelines.[3] We encountered a patient who had life‐threatening anaphylaxis with co‐amoxiclav 1 month after negative allergy investigations.

A 43‐year‐old woman was referred with a history of non‐drug related urticarial episodes and urticaria and angioedema of face, neck, and arms 30 minutes after a first dose of oral co‐amoxiclav 2 years previously. Specific immunoglobulin E tests to penicillin and amoxicillin, skin tests, and oral co‐amoxiclav challenge were negative. A month later, she developed anaphylaxis (intraoral angioedema, wheeze, hypotension [70/30 mm Hg], oxygen desaturation to 60% on room air, becoming unresponsive) within minutes of an intravenous dose of co‐amoxiclav for acute cholecystitis.