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

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.