891. Challenging the Dogma of Beta-Lactam Allergies: Impact of an Antimicrobial Stewardship Program

Abstract

Background Penicillin allergies are reported in approximately 10% of patients in the US but ∼90% of these allergies can be de-labeled. Consequences of inappropriate allergy labeling leads to use of alternative agents associated with increased adverse events and resistance rates, leading to worse outcomes. Though all beta-lactam agents share the core beta-lactam ring, the R1 side chain has been identified as the focus of cross-reactivity. Agents that do not share the same or similar R1 side chain are likely to have negligible risk of hypersensitivity reactions. The purpose of this study was to assess the incidence of hypersensitivity reactions in patients with a documented beta-lactam allergy that received a beta-lactam agent with a different side chain based on recommendation by an antimicrobial stewardship clinical pharmacist. Methods This was a retrospective, single-center, observational study of patients admitted to NYU Langone Hospital – Long Island from October 2019 to February 2022. Data was collected by review of the electronic medical record and descriptive statistics were generated as appropriate. The primary outcome was the proportion of patients that experienced a hypersensitivity reaction to a beta-lactam agent with a different side chain. Secondary outcomes included impact of antimicrobial stewardship intervention by clinical pharmacists, avoidance of alternative antibiotics, and cost comparison between agents requested and recommended. Results A total of 181 patients were included in the final analysis, including 37 patients with a history of anaphylaxis. No patients with a documented beta-lactam allergy experienced a hypersensitivity reaction upon receiving a beta-lactam agent with a different side chain. Within the cost comparison, meropenem accounted for 45.6% and 75.9% of the total minimum and maximum wholesale costs of requested agents, respectively. Conclusion The results of this study suggest that receipt of a beta-lactam agent with a different side chain is safe in patients with a history of beta-lactam allergy, including anaphylaxis history, and supports 'in the moment' antimicrobial stewardship intervention to ensure patients receive optimal therapy when access to in-depth allergy history or detailed patient interview is not feasible. Disclosures All Authors: No reported disclosures.