Diagnosis of penicillin allergy by means of Phadebas RAST penicilloyl G and V and skin tests.

Fifty patients with suspected allergy to penicillin were tested. Skin tests were done with Na-penicillin G and penicilloyl-polylysin. Specific IgE antibody assays were done with penicilloyl G and V conjugates by means of RAST. The overall agreement between skin test and RAST results was 87%, borderline cases not included. In one case, skin tests were positive to penicillamine only, while RAST for penicilloyl G and V both proved to be positive. One case of penicillin allergy could be diagnosed in vitro post mortem only. Two cases of Hoigné syndrome showed no evidence of allergy. Patterns of skin manifestations varied but urticaria was the most commonly seen feature. Twenty patients without adverse reactions to penicillin treatment and seven patients who had not received penicillin over the last 10 years served as controls. None of them were positive in either skin tests of RAST. Two or our twenty control patients developed penicillin allergy during the study. Both showed positive RAST results.