Epidemiology of hypersensitivity reactions to penicillin in Slovenia.

INTRODUCTION: The incidence of allergy to penicillin is highly overestimated. Many patients are labeled as penicillin-allergic, which is often unconfirmed. We report an analysis of patients that were referred for evaluation of suspected penicillin allergy in 2007 and 2008. METHODS: In a 2-year period, 606 patients were referred: 460 (76%) female, average age 42 (14-85) years. The diagnostic procedure started with specific IgE (sIgE) measurement, followed by skin prick and intradermal tests with PPL, MDM, and the suspected antibiotic. If all tests were negative, a drug provocation test was performed (DPT). If more than 3 years had passed from the reaction and if the reaction was not severe, the DPT followed serological tests. RESULTS: In 49 (8%) patients, sIgE to penicillin was detected. Skin testing was performed on 274 (45%) sIgE-negative patients, with positive results in 14 (5%) patients. In 426 (70%) patients, DPT with the suspected drug was performed, which was positive in 19 (4.5%) patients. Diagnosis of penicillin allergy was established in 82 (13.5%) patients. CONCLUSIONS: Tests of immediate hypersensitivity to penicillins were positive in a minority of patients referred. It is important to confirm or exclude suspected allergy to antibiotics because unnecessary use of more expensive broad-spectrum agents also contributes to the development and spread of certain types of drug-resistant bacteria.