# P-875. Evaluation of the treatment of infections caused by Stenotrophomonas maltophilia

## TL;DR

This study examines how treatment practices for Stenotrophomonas maltophilia infections changed after new guidelines were published.

## Contribution

The study evaluates real-world treatment shifts in response to updated IDSA guidelines for SMA infections.

## Key findings

- There was a small increase in the use of combination therapy after the IDSA guidelines were published.
- Levofloxacin use in monotherapy decreased in the post-guideline period.
- Infectious Diseases consultations increased from the pre- to post-guideline time periods.

## Abstract

The treatment of Stenotrophomonas maltophilia (SMA) presents many unique challenges. It is highly resistant and able to colonize medical lines and tubing. This study aimed to associate real-world practices with guideline-driven recommendations for the treatment of SMA infections.

This descriptive retrospective chart review evaluated the initiation of antimicrobial therapy, either monotherapy, combination therapy, or not treated, in hospitalized adult patients at ChristianaCare within 48 hours of a positive SMA culture. The study compares prescribing practices pre- and post-publication of the Infectious Diseases Society of America (IDSA) guidelines on antimicrobial resistant gram-negative infections that recommended all SMA infections be treated with combination therapy. Patients were eligible for inclusion if they had a positive blood or respiratory culture between January 2020 to December 2021 or between January 2023 to July 2024. Exclusion criteria were death prior to culture speciation or transition to hospice within 30 days of positive culture. Outcomes were measured in percentages; no statistical tests were measured.

In the pre- and post- groups respectively, 17 of 50 patients (34%) compared to 15 of 50 patients (30%) were not treated, 32 of 50 patients (64%) versus 23 of 50 patients (46%) were treated with monotherapy, and 1 of 50 (2%) compared to 12 of 50 (24%) were started on combination therapy. There was a high incidence of polymicrobial cultures in the not treated and monotherapy groups. Overall Infectious Diseases consultations were frequent across all treatment categories but increased from the pre- to post- time periods. Furthermore, the use of levofloxacin in monotherapy decreased in the post- group (11%) compared to the pre- group (24%).

The study found a small shift in SMA treatment practices at ChristianaCare towards combination therapy since the publication of IDSA guidelines. As a result, further education will be pursued to increased provider awareness of the recommended treatment strategies for SMA infections. In addition, investigators will continue to explore opportunities to use microbiology reports to encourage discernment between colonization and true infection.

All Authors: No reported disclosures