TOPLINE:

More than 80% of patients with a confirmed allergy to amoxicillin tolerated piperacillin-tazobactam, whereas 17.8% experienced cross-reactivity.

METHODOLOGY:

• Researchers evaluated tolerance to piperacillin-tazobactam in 28 patients (mean age, 39.5 years; 50% women) who had immediate allergic reactions to amoxicillin between January 2023 and December 2024.
• Researchers confirmed an amoxicillin allergy if patients had a specific immunoglobulin E level > 0.35 kU/L, positive skin test, or positive drug provocation test (DPT).
• All patients also underwent evaluation for allergy to piperacillin-tazobactam through skin testing, DPT, or both.

TAKEAWAY:

• Overall, 23 (82.1%) patients tolerated piperacillin-tazobactam during the DPT, and 67.9% tolerated other penicillins including cefuroxime and ceftriaxone.
• Five (17.8%) patients exhibited an allergy to piperacillin-tazobactam: two confirmed via positive skin tests and three via a positive DPT.
• All three DPT-positive patients developed acute urticaria after the administration of the first 500-mg dose, with one patient requiring adrenaline for persistent hives.
• No significant correlation was observed between the type of initial reaction to amoxicillin (anaphylaxis and urticaria) and tolerance to piperacillin-tazobactam.

IN PRACTICE:

“In [the study] sample of patients with amoxicillin allergy, 82.1% tolerated piperacillin-tazobactam, while 7% were allergic to all penicillins,” the authors of the study wrote. “In such cases, if piperacillin-tazobactam use is necessary, it is advisable to first perform ST [skin testing], followed by controlled administration by experienced allergists,” they added.

SOURCE:

Ana Rosado-Ingelmo, MD, PhD, with the Hospital Universitario Fundación Alcorcón, Alcorcón, Spain, was the corresponding author of this study, which was published online on August 22 in The Journal of Allergy and Clinical Immunology: In Practice.

LIMITATIONS:

This study was limited by its retrospective design and inconsistent testing for specific immunoglobulin E. Data on delayed cross-reactivity were unavailable, and the small sample size yielded wide CIs. Additionally, long-term tolerance to piperacillin-tazobactam in subsequent exposures remained unknown as this was a recent study.

DISCLOSURES:

The authors reported having no conflicts of interest.

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