Safety of amoxicillin provocation test using the PSU 2-step challenge in children with a history of non-immediate reactions

RATIONALE: A drug provocation test (DPT) is the gold standard for the diagnosis of a drug allergy in non-immediate reactions. Although patch testing, delayed reading intradermal test (IDT), and lymphocyte transformation test can be useful in children with non-immediate reactions, none have been standardized. The aim of this study is to evaluate the safety of the amoxicillin provocation test without skin test using the PSU 2-step challenge in children with a history of non-immediate reactions.

METHODS: Open drug provocation tests were performed in children with a history of nonimmediate cutaneous reaction without systemic symptoms. The PSU 2-step challenge is composed of 2 doses of amoxicillin with a 30-minute interval in the absence of antecedent skin testing. Provocation was continued for 4 days.

RESULTS: Thirty-one children had a median age of 5.9 years (range, 10 months-15 years) and 74% were male. Twenty-seven subjects (87%) and 4 subjects (13%) reported adverse reactions to amoxicillin and amoxicillin-clavulanic acid, respectively. The reactions were maculopapular rash in 27 (87%) and urticarial rash/angioedema in 4 (13%) children. The median time that elapsed between the suspected reaction and the DPT was 2.7 years (range, 2 months-13.5 years). Only one patient (3.2%) had a reaction during the provocation test, whereas 30 (96.8%) tolerated the culprit drug.

CONCLUSIONS: The PSU 2-step challenge seems to be a safe protocol even in the absence of antecedent skin testing in children with a history of non-immediate cutaneous reaction and without systemic symptoms.