A comparison of the performance of two penicillin reagent kits in the diagnosis of beta-lactam hypersensitivity.

BACKGROUND

Skin testing with penicilloyl polylysine (PPL) and minor determinant mixture (MDM) represents the first-line method for diagnosing beta-lactam hypersensitivity. However, in 2004, Allergopharma and Hollister-Stier announced their decision to stop the production of penicillin reagents (Allergopen and PrePen, respectively) within 1 year. Therefore, we decided to compare PPL and MDM from Allergopharma (Allergopen) with those from Diater (DAP).

METHODS

We skin-tested 195 subjects with both Allergopen and DAP reagents, as well as with other beta-lactams; 74 (group A) had had immediate reactions to beta-lactams and 74 (group B) nonimmediate reactions, while 47 (group C) underwent prophylactic tests.

RESULTS

One hundred two patients (52.3%) had positive skin tests; 29 (14.9%) were positive to PPL and/or MDM. Of the 102 skin-test-positive patients, 44 belonged to group A, 57 to B and 1 to C; the last was positive only to Allergopen PPL (PPL-A) and tolerated the benzylpenicillin challenge. Minor determinant mixture reagents produced identical results in the 148 patients of groups A and B, 22 (14.9%) of which were positive. Both PPL reagents produced negative results in 139 of these 148 patients and positive ones in 5; one subject was positive to DAP PPL (PPL-D) and negative to PPL-A, while three patients were positive to PPL-A and negative to PPL-D; two of the latter tolerated benzylpenicillin challenges.

CONCLUSIONS

Minor determinant mixture reagents produced identical results in all 195 patients. Results of skin testing with PPL reagents were concordant in 190 (97.4%) of them. Therefore, DAP reagents are a reliable alternative to Allergopen ones.