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Combination of timing and sings/symptoms predicts penicillin allergy test results

Published: September 12, 2022

In a recent study, published in The Journal of Allergy and Clinical Immunology: In Practice, Romano A and coworkers aimed at determining whether the combination of chronological (time of onset) and morphological (signs/symptoms of the index reaction) criteria could predict the results of diagnostic testing for penicillin allergy. They evaluated 1,074 patients by performing skin tests, serum specific IgE assays (ImmunoCAP), and drug challenges. Analysis of data revealed that: a) anaphylaxis is associated with a high probability of positive penicillin allergy test results, especially when the tests are performed within 6 months after the index reaction; b) patients not only experienced urticaria but also other cutaneous manifestations related to mast cell degranulation, such as angioedema and erythema, particularly if these skin manifestations  appeared within 1 hour after the first dose and regressed within 1 day (the so called “1-1-1” criterion); c) although sensitization can be lost over time,  a conversion to allergy test positivity can be observed in up to 20% of subjects with anaphylaxis retested after negative allergy workups, including challenges.

The study demonstrates that the combination of timing and signs/symptoms plays a determining role in the risk stratification of subjects with immediate hypersensitivity reactions to penicillins. In particular, the immediate  reactions to penicillins that are reproducible in  testing are usually “very immediate”. IgE sensitization to penicillins can be lost over time. In subjects with anaphylaxis, however, this phenomenon is not always definitive.  

The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.

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