What question did this study set out to answer?

Evaluate the outcomes of Clostridioides difficile infection after implementing a 2-step testing method.

January 14, 2026Open Access

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

Key Points

Evaluate the outcomes of Clostridioides difficile infection after implementing a 2-step testing method.
Monitored hospital-onset CDI by compiling data of positive C. difficile PCR results from January 2024 to April 2025.
Implemented 2-step testing (GDH and toxin A/B EIA) for patients with positive PCR results.
Reviewed treatment needs and outcomes at 28 days for patients with discordant results.
104 positive C. difficile PCR cases recorded during the study period.
75% of these cases had discordant results (positive PCR and negative toxin EIA).
60.3% of patients with discordant results were treated initially despite negative toxin EIA.
No patients with discordant results who were not treated initially required treatment at 28 days.
Zero CDI associated mortality rate observed in patients not treated initially.

Abstract

Abstract Background 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. Methods 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. Results 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. Conclusion 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. Disclosures All Authors: No reported disclosures

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