Diagnosing penicillin allergy in the absence of minor determinant mixture

Background Penicillin allergy is a common presentation in allergy clinic. The diagnosis of immediate hypersensitivity is made using clinical history, skin testing, specific IgE levels and oral challenge. Skin testing is done using benzyl penicilloyl-polylysine (PPL) and a minor determinant mixture (MDM) consisting of penicillin byproducts. Although using PPL and MDM is considered first line for diagnosis [1], our clinic is unable to consistently obtain MDM. We have undertaken a retrospective chart review to assess our current protocol in diagnosing penicillin allergy using Penicillin G (PG) alone instead of MDM.