Penicillin Allergy

The study aims to evaluate the effectiveness and safety of a collaborative nurse-allergist approach in penicillin allergy delabeling services. It also seeks to assess the impact on patients' quality of life and compare resource utilization and cost-effectiveness between the nurse-allergist collaborative approach and the traditional allergist-led approach.

This is a prospective non-inferiority study to evaluate penicillin allergy history in patients with reported penicillin allergy, who require penicillin or penicillin-derivative antibiotic during inpatient admission using a focused questionnaire. A simplified scoring system will be assigned to patient responses, and the total score will be utilized to identify low-risk patients that have a minimal risk of allergic reactions on exposure to penicillin or its derivative. Patients determined to have low risk based on this questionnaire will be offered a test dose (graded challenge) of amoxicillin in a supervised setting, and if they tolerate it, penicillin allergy label will be removed from patient's chart. We hypothesize that at least 95% of low-risk patients will successfully pass the graded amoxicillin challenge so the penicillin allergy label can be removed from their charts. A proportion as low as 0.85 would be a good clinical outcome and considered non-inferior to the expected proportion of 0.95.

The goal of this clinical trial is to learn about dosing when testing to see if a penicillin allergy label can be removed from adults that had been labeled as "penicillin-allergic" previously. The main question it aims to answer is: \- In penicillin-allergic patients that are at low risk of having an allergic reaction, is a one-dose oral challenge with amoxicillin (a penicillin-based antibiotic) as safe and effective as a two-dose oral challenge? Participants will, after being identified as having a low-risk penicillin allergy, be administered oral amoxicillin in a controlled setting and then monitored for an allergic reaction. Researchers will compare participants that took one dose of amoxicillin to participants that took two doses of amoxicillin (a small dose and then a larger dose) to see if either group was more likely to develop an allergic reaction.

The aim of this clinical trial is to analyze the negative predictive capacity and safety of risk-stratified direct drug provocation tests for patients with self-reported penicillin allergies. Patients reporting immediate or delayed penicillin allergies and defined as low-risk by the PEN-FAST score will receive drug provocation tests without prior skin testing.

Plenty of studies have now established the safety of low-risk penicillin allergy de-labelling, but few have addressed how to organise de-labelling at the clinic level. This study will test the real world practicalities of running a de-labelling clinic optimised for maximum patient volume. The sheer number of patients with a penicillin allergy label, in contrast to relatively few allergy centres, makes demonstrating that such an approach can work extremely important for future antimicrobial stewardship.