Methods: Thirty three patients were referred to our allergic clinic for testing of penicillin hypersensitivity in the period from 2008 to 2011: 22 (66,6%) females and 11 (33,4%) males, with ages ranging from 8 to 88 years. The first 24 (72,7%) patients were tested using only penicillin G, in the form of a prick test followed by an intradermal test with immediate reading, according to the Brazil Ministry of Health protocol (group I).
The remaining 9 (27,3%) patients (group II) were subjected to the adaptations of standards-based assessment of hypersensitivity reactions to beta-lactam antibiotics, according to the algorithmic recommendations of the European Network Drug Allergy (ENDA), which includes a prick test and intradermal test with penicillin G, amoxicillin and the suspected beta-lactam, such as clavulanic acid or cephalosporins, with immediate and delayed readings. Patients who had negative skin tests results, underwent a provocation test, which is considered the gold standard in determining drug hypersensitivity. In-vitro tests available in Brazil (specific IgE to penicillin and amoxicillin) were performed in patients with a history more suggestive of adverse reactions. It was respected the ENDA recommendation of not subjecting patients with severe reactions to this protocol.
Results: Of the 33 patients, 28 (84,8%) had negative results for the tests. One patient in group I showed inconclusive results. Four patients (12,2%) in group II had positive tests, including three for penicillin G and one for amoxicillin.
Conclusions: The results demonstrated that the clinical history collected by medical questionnaires is not the determining factor in confirming a patients’ reaction to penicillin, and shouldn’t be the only parameter used to exclude potential future prescriptions. In addition, the results denote that hypersensitivity to other beta-lactam antibiotics should be evaluated in a more proper way for a fuller understanding of each case.