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Ana Margarida Romeira1, Ana Castro Neves1; Cátia Alves1, João Marques1,2, Pedro Martins1,2, Paula Leiria Pinto1,2

1- Serviço de Imunoalergologia, Hospital Dona Estefânia, Centro Hospitalar de Lisboa Central, EPE, Lisboa;.
2- CEDOC, Integrated Pathophysiological Mechanisms Research Group, Nova Medical School, Lisboa, Portugal

- XXXVI European Academy of Allergology Clinical Immunology, Helsínquia, 17-21 Junho 2017
- Apresentação como poster; publicação de resumo
- Reunião Internacional
- Prémio de melhor apresentação/poster

Introduction The diagnostic evaluation of hypersensitivity reactions to betalactams (either immediate or nonimmediate) involves skin testing (prick, intradermal and patch tests), in vitro testing and drug provocation tests. The diagnostic algorithms proposed by the European Network for Drug Allergy (ENDA) include skin testing with penicilloyl-polylysine (PPL), minor determinant mixture (MDM) and benzylpenicillin (BP), along with the culprit drugs.
Objectives The aim of this work was to evaluate the role of PPL and MDM in the diagnosis of hypersensitivity to betalactams through skin tests.
Material and methods: We analysed retrospectively the diagnostic work-up applied to patients with a history of betalactam allergy performed in our Immunoallergy Department during 3 years (2014 to 2016). All patients performed skin prick and intradermal tests with PPL, MDM, BP, amoxicillin/clavulanic acid (AC), cefuroxime and the suspect betalactam. Drug provocation tests were performed according to the results (culprit or alternative betalactam).
Results A total of 105 patients were evaluated, 5 to 82-years-old (average 36,8 years; SD 21,8 years), 30 males and 75 females. The reactions were classified as immediate (until 1 hour after intake) in 41 patients and nonimmediate (more than 1h after intake) in 60 patients. In 4 patients it wasn’t possible to establish the chronology of the reaction. The skin tests (ST) were positive in 13 patients (12,4%): cefazolin (1), cefuroxime (1), BP (3: one with PPL and MDM negative and the other 2 with PPL and MDM positive) and AC (9). All of the PPL and/or MDM ST positives were also positive to BP. There was no systemic reaction associated with the ST. Seven patients with negative ST had a positive drug provocation test with the culprit drug. The NPV of the skin tests (BP, AC, cefuroxime and culprit, excluding PPL and MDM) was 92,4%.
Conclusions On our sample, the use of PPL and MDM in the diagnostic evaluation of hypersensitivity reactions to betalactams did not improve the allergy diagnosis. Skin testing was safe. Considering time consumption and costs, it might be reasonable to perform ST only with BP, AC, cefuroxime and the implicated betalactam. PPL and MDM could be performed in more severe cases (anaphylactic reactions, for instance) if the other tests are negative.

Palavras Chave: betalactam hypersensitivity. Betalactam allergy diagnosis