P-802. Assessing the Benefit of Adding a Rapid Antibiotic Susceptibility Platform for Bloodstream Infections to a Well-Established Stewardship Program within an Academic Health-system

TL;DR

This study evaluated whether adding a rapid antibiotic susceptibility test improved treatment timelines for bloodstream infections but found limited additional benefit.

Contribution

The study provides real-world evidence on the impact of integrating a rapid AST platform into an established antimicrobial stewardship program.

Findings

The AP group had faster initial susceptibility results but no significant difference in time to first appropriate therapy.

Seven AST discordances were found in the AP group, including four major errors indicating false resistance.

A well-established stewardship program may limit the added benefit of rapid AST in optimizing antibiotic regimens.

Abstract

Rapid diagnostic tests for pathogen identification and antimicrobial susceptibility testing (AST) have enhanced clinicians’ ability to promptly initiate appropriate antimicrobials and streamline regimens. The purpose of this study was to evaluate the benefit of adding the Accelerate Pheno® (AP) system for rapid AST to an existing blood culture identification multiplex polymerase chain reaction (mPCR) workflow in Gram negative bloodstream infections (GNBSIs).

A multi-centered, retrospective, quasi-experimental study was conducted in patients hospitalized with aerobic GNBSIs between August 2022 and August 2024. Notable exclusions were patients with polymicrobial GNBSIs and those who were no longer hospitalized prior to initiation of antibiotic therapy or blood culture results. The primary endpoint of time to first appropriate streamlined therapy (FaST) was compared between an AP group and post-AP group during a 3-month period. Key secondary endpoints included time to first and final AST, time to de-escalation and notable discordances in AST.

Among 355 charts reviewed, 228 patients were included in the analysis (125 in the AP group and 103 in the post-AP group). Baseline characteristics were similar between groups. A faster median time to initial susceptibilities was observed in the AP-group (39 h vs. 65.5 h, p< 0.0001). However, a median difference of 23.3 h to final susceptibilities was observed between the AP-group and the post-AP group (93.2 h vs. 69.9 h, p=0.008). A total of seven AST discordances were identified in the AP-group, four of which were major errors (false resistance). There was no significant difference in the median time to FaST (22.8 h vs. 11.6 h, p=0.2) or median time to de-escalation (41.9 h vs. 42 h, p =0.527).

The addition of the AP system did not appear to have a meaningful impact on time to FaST or time to de-escalation compared with a historical mPCR and antimicrobial stewardship program (ASP) workflow, despite a more rapid availability of first AST. The study findings may be explained by local susceptibility rates and a well-established ASP that performs prospective audit and feedback on all positive blood cultures with early antibiotic optimization guided by prediction tools and mPCR results.

All Authors: No reported disclosures