TOPLINE:

Nearly 1 in 5 patients with confirmed amoxicillin hypersensitivity also reacted to piperacillin-tazobactam; most cross-reactions were identified using skin testing.

METHODOLOGY:

• Researchers analyzed data from 49 patients with confirmed amoxicillin hypersensitivity (mean age, 47.5 years; 61.2% female), including 25 who reacted to amoxicillin and 24 who reacted to amoxicillin-clavulanic acid in Salamanca, Spain, between January 2024 and July 2025.
• Skin testing, specific immunoglobulin E measurement, drug provocation testing, and clinical history were used, where indicated, to diagnose amoxicillin allergy.
• Most patients had immediate reactions to amoxicillin within 1-6 hours of drug administration, and about half experienced anaphylaxis.

TAKEAWAY:

• Nine (18.4%) patients exhibited cross-reactivity with piperacillin-tazobactam.
• In eight of the patients, cross-reactivity was diagnosed via positive skin testing.
• In one patient with negative skin testing, cross-reactivity was diagnosed by drug provocation testing in a hospital setting.
• The patient developed bronchospasm after administration of a 1/0.125-g piperacillin-tazobactam dose, which “resolved promptly with intramuscular epinephrine, intravenous methylprednisolone, and inhaled salbutamol,” the researchers of the study reported.

IN PRACTICE:

“These results highlight the importance of a systematic allergy evaluation, including both [skin testing] and supervised [drug provocation testing],” the authors of the study wrote. “Such an approach ensures that most patients with [amoxicillin] allergy can safely receive [piperacillin-tazobactam] when needed, while protecting the clinically relevant minority at genuine risk.”

SOURCE:

Esther Moreno, MD, PhD, University Hospital of Salamanca, Salamanca, Spain, was the corresponding author of the study, which was published online on January 16 in Annals of Allergy, Asthma & Immunology.

LIMITATIONS:

The study was limited by its single-center design, the inability to perform drug provocation testing in patients with a history of recurrent fixed drug eruption, and the lack of data on long-term outcomes after therapeutic use of piperacillin-tazobactam.

DISCLOSURES:

One author reported receiving payments from pharmaceutical companies for lectures, serving on speakers bureaus, consulting, and grants.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.