Intradermal penicillin skin test is more likely to be positive compared to prick skin test in patients with a history of penicillin allergy

Background Penicillin skin testing (PST) with the major determinant (benzyl-penicilloyl) and minor determinant mix (penicillin G, benzyl-penicilloate, and benzyl-penilloate) is one of the major diagnostic tools in the evaluation of a penicillin allergy mediated by IgE. The PST begins with a skin prick test (SP) with the above components and, if negative, then proceeds to an intradermal testing (ID). However, it is unclear in the literature, how often the PST is positive to SP compared to ID testing. Hence, we conducted this study to determine the rates of positive PST to SP compared to ID skin test.