Safety and efficacy of direct two-step penicillin challenges with an inpatient pharmacist-driven allergy evaluation

Background: Penicillin allergy is commonly reported and has clinical and financial consequences for patients and hospitals. A penicillin evaluation program can safely delabel patients and optimize antibiotic therapy. Pharmacists who perform this task have focused on a detailed interview or penicillin skin testing (PST). Antibiotic graded challenge after PST requires more resources and is more costly than going directly to a two-step challenge. Objective: To determine whether a pharmacist-driven penicillin allergy evaluation and a testing protocol that primarily uses direct oral challenges can safely delabel patients. Methods: Adult patients (ages >18 years) with a penicillin allergy in their electronic medical record (EMR) who were admitted between September 2019 and June 2020 were eligible. Although all patients with penicillin allergy were eligible, priority was given to patients who required antibiotics. Patients were interviewed, and, if indicated, based on an institutional protocol, were tested by using PST and/or two-step oral challenge. If the patient passed the challenge, then the penicillin allergy label was removed in the EMR and the patient counseled. Demographic information, allergy questionnaire results, testing results, and changes in antimicrobial therapy were collected. Results: Fifty patients were evaluated from September 2019 to June 2020. Ninety-six percent of the patients were delabeled, and antibiotic therapy changed for 54%. Twenty patients were delabeled with an interview alone, and 30 patients underwent oral two-step challenge. Only one patient required PST. Conclusion: A pharmacist-driven penicillin allergy evaluation program focused on direct oral graded challenges and bypassing PST can effectively delabel admitted patients. However, more safety data are needed before implementation of similar programs to optimize antibiotic treatment.