Delayed hypersensitivity reactions to piperacillin-tazobactam

We read with great interest Gallardo et al's1 article recently published in The Journal of Allergy and Clinical Immunology: In Practice regarding immediate hypersensitivity reactions to piperacillin-tazobactam (PipTaz) confirmed by either skin or drug provocation testing. Of interest are the key identification of different immediate-type hypersensitivity phenotypes and the systematic approach to clinical diagnostic as well as in vivo testing. The authors also performed drug provocation tests in the 2 patients with negative skin testing to confirm the drug allergy label.