[Clinical significance of positive penicillin test reactions (author's transl)]

Epicutaneous, scratch and intracutaneous tests with various penicillins and their major as well as minor determinants were performed on 495 patients either because they were suspected of having a penicillin allergy, or in order to exclude such allergy, or before starting penicillin treatment, or because they suffered from chronic recurrent urticaria. A positive test reaction occurred in 25%: 44% among those with a history pointing to penicillin allergy and 17.8% among those who were tested before treatment to exclude penicillin allergy. Positive reactions also occurred in 11% of patients with chronic recurrent urticaria, but in practically all instances were clinically without significance. D-Penicillamine (Metalcaptase) and penicilloyl-polysine in the intracutaneous test, penicillin-G-sodium and ampicillin in the epicutaneous test gave the highest incidence of positive reactions.