Penicillin allergy – recommendations for diagnostic work up and patient management

Background: Allergy to penicillins or cephalosporins manifests either within a few minutes after intake or infusion in the form of acute anaphylaxis symptoms, or several hours to days later as exanthematous skin reactions. Exanthematous skin eruptions caused by amoxicillin or ampicillin are currently the most frequently diagnosed clinical reaction pattern within the spectrum of penicillin allergy. Certain single cephalosporins such as cefazolin, ceftriaxone, and cefuroxime are gaining in relevance as triggers of β‑lactam antibiotic-induced IgE(Immunglobulin E)-mediated anaphylaxis reactions. Methods: This article provides an overview of selected scientific articles and is based on research in PubMed, studies, and specialist databases. Results: Penicillin allergy work-up is based on patient history and documented medical findings; serological IgE determinations, as well as skin and provocation testing, are routinely performed. While the determination of IgE directed to certain penicillin determinants is one of the few reliable laboratory tests for the diagnosis of drug hypersensitivity, the basophil activation test or the lymphocyte transformation test are reserved for experienced laboratories which are able to critically evaluate their test results. Wheal-and-flare reactions in skin prick and intradermal testing suggest IgE-mediated allergy, while infiltrated erythematous or exanthematous plaques in patch or intradermal testing point to delayed-type hypersensitivity. Conclusion: The overall predictive value of combined in vitro and in vivo allergy testing with β‑lactam antibiotics is approximately 90%. However, subsequent controlled provocation testing is recommended in order to reliably exclude allergic hypersensitivity. © 2018, Springer Medizin Verlag GmbH, a part of Springer Nature.