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The Standards of Care Committee of the British Society for Allergy and Clinical Immunology (BSACI) and a committee of experts and key stakeholders have developed this guideline for the evaluation and testing of patients with an unsubstantiated label of penicillin allergy. The guideline is intended for UK clinicians who are not trained in allergy or immunology, but who wish to develop a penicillin allergy de-labelling service for their patients. It is intended to supplement the BSACI 2015 guideline "Management of allergy to penicillin and other beta-lactams" and therefore does not detail the epidemiology or aetiology of penicillin allergy, as this is covered extensively in the 2015 guideline (1). The guideline is intended for use only in patients with a label of penicillin allergy and does not apply to other beta-lactam allergies. The recommendations include a checklist to identify patients at low risk of allergy and a framework for the conduct of drug provocation testing by non-allergists. There are separate sections for adults and paediatrics within the guideline, in recognition of the common differences in reported allergy history and likelihood of true allergy., (© 2022 John Wiley & Sons Ltd.)

Background: Previous reports have suggested that drug-specific lymphocyte proliferation assays (LPA) can be used retrospectively to confirm the culprit drug following delayed-type drug hypersensitivity reactions (DHR). However, only limited evidence supports their use in aiding acute clinical management. The aim of this study was to compare the LPA against combination cytokine assays for potential use in the acute setting., Methods: A total of 43 patients with DHR (19 during the acute reaction, 20 after recovery, four during acute and after recovery) and 14 control subjects without DHR were investigated using ex vivo analysis of drug-specific proliferation, and interferon (IFN)-γ and interleukin (IL)-4 production., Results: Healthy controls showed negative drug-specific proliferation and cytokine release in contrast to individuals with a known sensitivity (P < 0·0001). The assays demonstrated a test specificity of 95% (LPA), 83% (IFN-γ) and 92% (IL-4). The sensitivity of combined measurement of drug-specific IFN-γ and IL-4 cytokines during acute DHR was better than LPA (82% vs. 50%), but all assays were less sensitive during the recovery phase. The correlation between LPA and IFN-γ assays was strong (r = 0·7, P < 0·0001), whereas the IL-4 assay did not correlate as well with either of these assays. In contrast to LPA, drug enzyme-linked immunosorbent spot assays showed positive responses in patients concurrently taking immunosuppressive medication., Conclusions: In vitro assays of drug-specific IFN-γ and IL-4 production offer potential for use as rapid diagnostic tests. Cytokine detection offers distinct advantages over the LPA, including a shorter assay time, a greater sensitivity and effectiveness in testing immunosuppressed patients., (© 2012 The Authors. BJD © 2012 British Association of Dermatologists.)

Purpose of Review: The review intends to clarify understanding of when and how skin patch tests can be used to help drug allergy diagnosis and identify causally relevant drugs. It aims to give an understanding of which clinical patterns of drug reaction are produced by T-lymphocyte-mediated pathomechanisms since these are what are detected by patch tests. It also covers fundamental principles underlying patch test methodology and summarizes clinical patterns and causal drugs for which patch tests have reasonable value to diagnose culprit drugs., Recent Findings: A number of recent studies have consolidated evidence that the use of patch tests in drug hypersensitivity diagnosis is not a robust science. The field is bedeviled by the lack of standardized approach to ascertain and define clinical entities in a sufficiently clear way that allows researchers to be confident that patch tests are used appropriately in T-cell-mediated clinical conditions. The literature is confounded by case series including patch tests from conditions which may be the wrong type of test causing the sensitivity of the test system to be measured incorrectly., Summary: For certain drug eruptions mediated by T cells (exanthemata, acute generalized exanthematous pustulosis, drug rash with eosinophilia and systemic symptoms, erythema multiforme/toxic epidermal necrolysis, fixed drug eruption and symmetrical drug-related intertriginous and flexural exanthem) patch tests can elicit positive responses in a proportion of cases. The test works best with aromatic anticonvulsants and various antibiotics but does not appear to work consistently with a wide range of drugs. A coordinated and systematic research effort is required to resolve inconsistencies to encourage greater utilization of this potentially important diagnostic methodology.