Embedding penicillin de-labelling in the AMU: a feasibility and safety pilot study with exploratory economic and environmental analysis

Background: Penicillin allergy labels affect 6-10% of the UK population, yet over 95% are inaccurate. These labels drive unnecessary broad-spectrum antibiotic use, antimicrobial resistance, healthcare costs, adverse patient outcomes and carbon emissions.
Methods: This pilot study embedded a penicillin allergy de-labelling (PADL) clinic within an Acute Medical Unit, using a direct oral amoxicillin challenge for patients identified as low-risk for a true allergy to penicillin according to BSACI guidelines and PEN-FAST scoring. Primary outcomes were feasibility and safety. Secondary outcome was subsequent antibiotic prescribing patterns. Exploratory outcomes included retrospective economic, antimicrobial resistance and environmental impact modelling.
Results: Sixty patients (mean age 56 years) were included in the study, of whom 59 (98%) were successfully de- labelled with one delayed type IV reaction but no anaphylaxis. Following de-labelling, 35% received subsequent antibiotic therapy and all were prescribed penicillin-based therapy. Retrospective analysis revealed antibiotic costs were approximately tenfold higher (£19,364 versus £2,092) due to allergy labels. Multidrug-resistant organisms were present in 47% of patients and 37% received unnecessary intravenous antibiotics.
Conclusion: This pilot suggests that AMUembedded penicillin delabelling is safe and feasible, and may be associated with important clinical, economic, antimicrobial stewardship and environmental benefits that warrant confirmation in larger studies.