Patterns of response and drugs involved in hypersensitivity reactions to beta‐lactams in children

Background Beta‐lactams generate different allergenic determinants that induce selective or cross‐reactive drug hypersensitivity reactions (DHRs). We aimed to identify the drugs involved, the selectivity of the response, the mechanism, and the value of the different diagnostic tests for establishing a diagnosis in children evaluated for DHRs to beta‐lactams. Methods Prospective study evaluating children aged under 16 years reporting DHRs to beta‐lactams. Reactions were classified as immediate and non‐immediate reactions. The workup included sIgE, skin testing, and drug provocation tests (DPTs) for immediate reactions and patch testing and DPTs for non‐immediate ones. Results Of the 510 children included, 133 were evaluated for immediate reactions and confirmed in 8.3%. Skin test/in vitro IgE contributed to diagnosing half of the cases. Selective reactions occurred with amoxicillin (63%), followed by common penicillin determinants (27%) and cephalosporins (0.9%). Among non‐immediate reactions (11.4% of the 377 children evaluated), most required DPTs, 52.7% of which were positive at 6–7 days of drug challenge. Selective reactions were identified with amoxicillin (80%), penicillin G (7.5%), cephalosporins (7.5%), and clavulanic acid (5%). Urticaria and maculopapular exanthema were the most frequent entities. Conclusions There were few confirmed cases of either type of reaction. Skin testing proved less valuable in non‐immediate reactions, over half of which would also have been lost in a short DPT protocol. Selective responders to amoxicillin were more likely to have non‐immediate reactions, while clavulanic acid selectivity was exclusive to the non‐immediate typology. Over half the cases with DPTs required 6–7 days of treatment for DHR confirmation.