Assessment of a new brand of determinants for skin testing in a large group of patients with suspected beta-lactam allergy.

BACKGROUND

Skin testing with major and minor determinants of benzylpenicillin is recommended standard practice for the evaluation of patients with immediate hypersensitivity reactions to beta-lactams. However, commercial reagents for this purpose were recently dropped from the European market.

OBJECTIVE

In the present study, we assessed a new brand of reagents for use in skin testing in patients with suspected penicillin allergy.

METHODS

Prick tests and intradermal tests were performed with benzylpenicilloyl polylysine (PPL) and minor determinant mixture (MDM). Penicillin G, amoxicillin, and the culprit beta-lactam were also tested. If skin tests were negative, a single-blind oral challenge test was performed with the culprit active principle or penicillin. If both skin tests and challenge tests were negative, the same procedure was repeated between 2 and 4 weeks later.

RESULTS

A total of 636 patients were assessed. The allergy study was positive in 69 patients. Skin tests with PPL were positive in 30 patients (46.8%) and with MDM in 28 (43.7%). Sixteen patients displayed a positive reaction to both PPL and MDM (25%), while 42 patients (65.6%) had a positive reaction to either PPL or MDM alone. Thirty-two patients had positive skin test reactions to penicillin G or another p-lactam antibiotic. Five patients in whom a negative result was obtained in skin tests had a positive reaction to oral challenge.

CONCLUSIONS

Our results indicate that a new brand of determinants that is commercially available in Europe is a reliable and useful tool for the diagnosis of beta-lactam allergy. The new reagents are a safe alternative to the previously available brand.