# P-1011. Clostridioides difficile infection outcomes following implementation of 2-step testing at a large Veterans Affair hospital in South Texas

## TL;DR

A hospital in Texas implemented a two-step testing method for Clostridioides difficile and found no deaths in patients with conflicting test results who weren't treated immediately.

## Contribution

The study evaluates the impact of two-step C. difficile testing on infection outcomes and treatment decisions in a real-world healthcare setting.

## Key findings

- 75% of positive C. difficile PCR tests had discordant results with toxin EIA.
- 60.3% of discordant cases were treated initially despite negative toxin tests.
- No mortality occurred in untreated discordant cases at 28 days.

## Abstract

Clostridioides difficile is a significant pathogen in community-onset and healthcare facility-onset diarrhea. Clostridioides difficile infection (CDI) remains a diagnostic challenge in healthcare. Guidelines for C. difficile testing recommend a multistep algorithm (GDH + toxin, GDH + toxin arbitrated by NAAT, or NAAT + toxin) rather than NAAT testing alone. Our institution implemented 2-step C. difficile testing 01/08/2024, to reduce rates of hospital-onset Clostridioides difficile infections (HO-CDI). Our study aims to evaluate the CDI outcomes following implementation of 2-step testing at Audie L. Murphy Veterans Affair hospital in San Antonio, Texas.

A multidisciplinary team monitoring HO-CDI compiled data of all positive C. difficile PCR results during the study period (January 8, 2024 to April 15, 2025). Two-step testing (GDH and toxin A/B EIA) was subsequently performed on patients with positive PCR results. Of the total positive PCR results we evaluated the number of cases with positive PCR and negative toxin EIA. We investigated how many patients were treated initially despite discordant results (positive PCR and negative toxin EIA). Additionally, of those patients with discordant results who were not treated initially we reviewed 1) how many required treatment at 28 days and 2) CDI associated mortality at 28 days.

There were 104 cases of positive C. difficile PCRs during the study period. 78 of the 104 cases were patients with discordant results (75%). 47 of the 78 cases (60.3%) were treated initially despite positive PCR and negative toxin A/B EIA. None of the 31 cases with discordant results, which were not treated initially, required treatment at 28 days. CDI associated mortality at 28 days in those patients with discordant results who were not treated initially was zero.

Our study demonstrates the reassuring CDI outcomes at 28 days in patients who had discordant 2-step testing results (positive PCR and negative toxin EIA). There was zero CDI associated mortality rate at 28 days in those patients who were not treated initially. This highlights the importance of the implementation of 2-step testing for Clostridioides difficile to improve diagnostic stewardship and minimize unnecessary treatment in patients who may be colonized with C. difficile.

All Authors: No reported disclosures