Evaluation and characterization of 125 patients with a history of reaction to beta-lactams

Abstract

Background: Reactions to beta-lactams are frequent and it is difficult to establish the relationship between the drug and symptoms. Objective: To describe the clinical characteristics and explore the immunological mechanisms of patients with suspected adverse reaction to beta-lactams. Methods: Retrospective study of patients with a history of beta-lactam reaction and tests for reactions to drugs. Results: Out of 125 patients, 71 were women (56.8%); 73 had a history of immediate reaction and 52 delayed reaction; 590 allergy tests were done: specific IgE measurement, skin prick, patch, and provocation tests. The drugs most often related were amoxycillin, in 62 patients (49.6%), crystalline penicillin in 17 (13.6%), benzathine penicillin in 15 (12%), and cefalexin in 13 (10.4%). The severity of the reaction was mild in the majority (82%). 7.7% had a history of anaphylaxis and 10.8% sought care for a positive penicillin skin test, without history of reaction. Only 6.7% resulted in a positive test. More than 62% began testing two years after the reaction for which they sought care. Conclusions: The clinical history is insufficient to determine allergy to beta-lactams. In our sample, few patients with a history of beta-lactam reaction had evidence of immune-mediated reactions.