Skin and patch tests of Italian cases
On the first day, prick and intradermal tests with immediate and delayed reading were carried out using penicilloyl-polylysine, minor determinant mixture , and benzylpenicillin as described previously.16 Patch tests were administered with benzylpenicillin, ampicillin, amoxicillin, cephalexin, cefaclor, and cefadroxil in petrolatum as described.17 All reagents of patch testing were applied to uninvolved skin on the interscapular region of the patient’s back, using acrylate adhesive strips with small plates attached for test allergens (Curatest, Lohmann GmbH & Co. KG, Neuwied, Germany), as previously described.17Occlusion time was 48 hours. Readings of patch tests were made 15 minutes after removal of the strips and 48 hours later. Positive reactions were scored as: + (erythema, infiltration, possibly discrete papules); ++ (erythema, infiltration, papules, and vesicles); and +++ (intense erythema, infiltration, and coalescing vesicles). Participants who had negative results in the allergy tests with the alternative cephalosporins concerned underwent controlled administrations of therapeutic doses of ceftriaxone (1 g), intramuscularly, as well as cefuroxime axetil (500 mg), cephalexin (1 g), cefaclor (500 mg), and cefadroxil (500 mg), orally, each in a different day and in the above order, as previously described.16 In case of a positive response to an aminocephalosporin, the others were not administered. Patients were carefully monitored during all allergy testing, and for six hours after challenges. They were also asked to return to the clinical department to show any positive responses.