# P-2041. Implementing Revised Cefazolin Use Criteria within a Pharmacy-to-Dose Protocol to Improve Guideline-Concordant Antibiotic Prophylaxis in Beta-Lactam Allergic Surgical Patients

## TL;DR

Changing cefazolin use rules in a pharmacy-to-dose system helped more beta-lactam allergic patients receive the preferred antibiotic without increasing allergies.

## Contribution

Shows how revised cefazolin criteria in a pharmacy-to-dose protocol can improve antibiotic use in beta-lactam allergic patients.

## Key findings

- Cefazolin use increased from 69.9% to 90.8% after revised guidelines.
- Alternative antibiotic use dropped from 30.2% to 8.5%.
- PTD sites had higher cefazolin use than non-PTD sites before and after implementation.

## Abstract

β-lactam allergy (BLA) labels in the preoperative setting often lead to avoidance of cefazolin in favor of alternative agents, increasing the risk of surgical site infections, adverse events, antimicrobial resistance, and healthcare costs. Although recent literature supports preoperative cefazolin use in BLA-labeled patients, data on implementing sustainable, scalable system-wide changes to increase cefazolin use remains limited.

This multi-center, retrospective cohort study included adults with complete allergy data who underwent initial surgery with preoperative antibiotics at one of three Munson Healthcare sites (MMC, MHC, MHG) between 1/1/2020, and 12/31/2024. Outcomes were compared before and after a revision to the preoperative antibiotic prophylaxis guidelines on 2/28/2023, promoting cefazolin use for all patients except those with a cefazolin allergy or a BLA-label consistent with a type II-IV reaction. The primary outcome was rate of prophylactic cefazolin use among BLA-labeled patients, with a subgroup analysis comparing two sites (MMC, MHC) with pharmacy-to-dose (PTD) antibiotic prophylaxis protocols to one site (MHG) without such a protocol. Secondary outcomes included rates of alternative prophylactic antibiotic use and new cefazolin allergies within 24 hours.

Among 39,104 included patients, BLA-label rates were similar pre- and post-intervention (21.0% vs. 20.8%; p=0.56). Following implementation of the revision, cefazolin usage among BLA-labeled patients increased from 69.9% to 90.8% (p< 0.001), while alternative antibiotic use declined from 30.2% to 8.5% (p< 0.001). All sites saw significant increases in cefazolin use among patients with a BLA-label (p< 0.001); however, usage remained higher at PTD sites compared to the non-PTD site both pre- (71.5% vs. 48.1%) and post-implementation (92.6% vs. 65.6%), with a larger absolute increase at PTD sites (p< 0.001). The incidence of new cefazolin allergies within 24 hours remained unchanged (0.01% vs. 0.03%; p=0.26).

Implementing revised cefazolin use criteria within a PTD antimicrobial prophylaxis protocol increased cefazolin use while reducing alternative antibiotic use among BLA-labeled patients, without increasing new cefazolin allergies within 24 hours.

All Authors: No reported disclosures