Delayed-Type Hypersensitivity Reactions to Penicillins

Intradermal tests with delayed reading, patch tests, and occasionally prick tests provide the mainstay diagnostic procedures for the evaluation of delayed reactions to penicillins and other 

In a prospective investigation of allergic crossreactivity between aminopenicillins, phenoxy-methylpeiuciUin, and two cephalosporins with different R1 side chains, 71 patients (57 with a history of macnlar or macnlopapular exanthema, two with erythema mnitiforme-like exanthema, nine with acnte nrticaria, and three with unclassified symptoms) were evalnated with intradermal and patch tests. Sixty eight of the 71 patients (95.8 %) had at least one positive intradermal or patch test to ampicillin or amoxicillin, 48 reacted to the aminopenicillins only, four to the aminopenicillins and benzylpenicillin, and 16 to the three penicillins pins phenoxymethylpeniciUin. Erom these resnlts, intradermal and patch tests were 

The usefulness of the penicillin major and minor determinants in evaluating delayed reactions to penicillins was assessed in intradermal and patch tests on 162 patients who experienced delayed reactions to penicillins, mainly aminopenicillins. Positive intradermal and/or patch tests in 157 patients (96.9 %) to the responsible penicillin reagents indicated cell-mediated hypersensitivity while only 9 (5.5 %) and 17 (10.5 %) were positive to penicilloyl-polylysine and minor determinant mix, respectively, demonstrating the limited usefulness of the two benzylpenicillin determinant preparations. 

Prick and intradermal tests with penicillins should be read after 20 min and delayed reactions in the intradermal test after 48 and 72 h. Positive 

3 Delayed Reactions to Penicillins and the Lymphocyte Transformation Test 

---