P-195. Clinical Clostridioides difficile Diagnostic Test Types and Results are Associated with the Likelihood of Recovering C. difficile in Stool Cultures
Authors: Skinner Andrew M , Guh Alice , Petrella Laurica A , Sambol Susan P , Johnson Stuart , Czaja Christopher A , Johnston Helen , Basiliere Elizabeth , Dhonau Robin , Korhonen Lauren C , Paulick Ashley , Adamczyk Michelle , McDonald L Clifford , Gerding Dale N 
Published: January 2025

Abstract

Background
Active Clostridioides difficile infection (CDI) surveillance is conducted by the U.S. CDC’s Emerging Infections Program (EIP) and includes collection of a convenience sample of stool specimens from C. difficile positive cases. Accurate molecular epidemiology relies on recovering C. difficile from clinical specimens. We sought to determine whether CDI diagnostic testing approach was associated with the likelihood of culturing C. difficile from stool.Table 1.Characteristics of stool specimens collected from Clostridioides difficile positive stool specimens identified through Emerging Infections Program surveillance in Colorado and Georgia, January 2020 through December 2022

Methods
We performed a cross-sectional study of the recovery of C. difficile from C. difficile positive stools collected from 1/2020 – 12/2022 from the Colorado and Georgia EIP sites. Stools were collected and stored per site protocols (i.e. Cary-Blair transport medium [CBTM] or fresh stool), frozen, and cultured at a reference laboratory. Multivariable logistic regression models were constructed to determine the adjusted odds ratio (aOR) for key variables in relationship to C. difficile recovery. A separate semi-quantitative experiment evaluating the impact of CBTM on recovery was conducted by placing stools in which C. difficile had been recovered into CBTM vs. phosphate-buffered saline (PBS).Table 2.Multivariable logistic regression models for Clostridioides difficile recovery from C. difficile positive stool specimens identified through Emerging Infections Program surveillance in Colorado and Georgia, January 2020 through December 2022

Results
C. difficile was cultured from 1569 of 1921 stools (81.7%, Table 1). Semi-quantitative experiments revealed that CBTM had no impact on C. difficile recovery. Recovery of C. difficile from stool cultures was less likely among cases in which C. difficile was detected: 1) by multiplex PCR (aOR 0.45, 95% confidence interval [CI]: 0.32-0.62); 2) with a negative toxin enzyme immunoassay (EIA) (aOR 0.12, 95% CI: 0.06-0.22); and 3) by a PCR-only testing strategy (aOR 0.24, 95% CI: 0.12-0.45). Among 1056 cases with known toxin EIA test results, C. difficile recovery was less likely when C. difficile detection was associated with a multiplex PCR and in those with a negative toxin EIA (Table 2).

Conclusion
The ability to culture C. difficile from stool specimens was reduced when C. difficile was detected with a multiplex PCR, a PCR-only testing strategy, or with negative toxin EIA results. These findings can be used to maximize the yield of surveillance stool submission and culture protocols, thereby enhancing the ability to generate robust molecular epidemiology data to inform prevention and control efforts.

Disclosures
Andrew M. Skinner, MD, BioK plus: Advisor/Consultant|Ferring Pharmaceuticals: Advisor/Consultant|Recursion pharmaceutical: Advisor/Consultant Stuart Johnson, M.D., Acurx Pharmaceuticals: Advisor/Consultant|Bio-K Plus International: Advisor/Consultant|Ferring Phamraceuticals: Advisor/Consultant Dale N. Gerding, MD, AstraZeneca: Advisor/Consultant|Destiny Pharma: Advisor/Consultant|Destiny Pharma: Licensed IP to Destiny|Sebela: Advisor/Consultant|Sebela: Licensed IP