C. Difficile Toxin Levels in Stool From Healthy Individuals Following Standard of Care Antibiotic Treatment for CDI.

A Prospective, Observational Study to Evaluate C. Difficile Toxin Levels in Stool in Healthy Individuals Following Standard of Care Antibiotic Treatment for CDI.

Hospitals and clinics interested in participating in this multi-site study, please contact the people mentioned under "Contacts and Locations".

The goal of this study is to map the risk of having a C. Difficile infection recurrence (rCDI) after being treated with standard-of-care antibiotics for a C. Difficile infection.

The main questions it aims to answer are:

• What is the recurrence rate of CDI in the 8 weeks following antibiotic treatment for a first recurrence of CDI?
• Does toxin levels of Toxin A and/or B from C. Diff. at baseline predict CDI recurrence risk?

Participants will:

• Undergo standard of care Antibiotic treatment for first recurrence of CDI
• Visit their clinic at 4 different visits over a time period of approximately 9 weeks. (Visits can also be performed remote/via phone call.)

Study Overview

• Status: Recruiting
• Conditions: Clostridioides Difficile Infection Recurrence
• Intervention / Treatment: Other: Participants that are undergoing standard of care antibiotic treatment for their second C. Diff infection will be followed for 8 weeks after completing antibiotic treatment.

Detailed Description

Hospitals and clinics interested in participating in this multi-site study, please contact the people mentioned under "Contacts and Locations".

This prospective observational study will enrol 60 otherwise healthy adults with a documented history of first recurrent Clostridioides difficile infection (rCDI). Eligible participants must have had a confirmed positive toxin B test for C. difficile, with the initial infection occurring within the past 12 months. At the time of enrolment (Day 0), participants must have completed a standard-of-care oral antibiotic therapy for their first rCDI no more than five days prior and be asymptomatic for CDI. Potential participants will sign an informed consent form at their initial visit to their doctor (visit 1) and provide a stool sample for c diff testing. Participants will only be considered 'enrolled' if their stool sample is positive for toxin B and they meet all other criteria at visit 2 (week 0).

The primary objective of the study is to measure the rate of CDI recurrence within an 8-week follow-up period. The secondary objective is to assess stool levels of Toxin A and B at baseline, week 2, and week 8. The second objective will enable exploration of the reliability of using high-sensitivity assays for toxin detection in stool. Further, potential correlations between post-treatment stool toxin levels and rCDI development will be explored.

• Study Type: Observational
• Enrollment (Estimated): 60

Contacts and Locations

• Study Contact: Name: Kevin O' Regan Senior Operations Manager, Atlantia Clinical Trials; Phone Number: +1 312 818 8905; Email: koregan@atlantiatrials.com

Study Locations

• United States
  • Georgia
    • Atlanta, Georgia, United States, 30322
      • Recruiting
      • Emory University Hospital
      • Principal Investigator: Colleen S Kraft, MD, MSc
      • Contact: Jennifer C Truell, MA, MPH; Phone Number: 404-778-0014; Email: jennifer.carter.truell@emory.edu
      • Contact: Colleen S Kraft, MD; Phone Number: 404-712-8889; Email: colleen.kraft@emory.edu
      • Sub-Investigator: Nirja Mehta, MD

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

This prospective observational study will enrol 60 otherwise healthy adults with a documented history of first recurrent Clostridioides difficile infection (rCDI). Eligible participants must have had a confirmed positive toxin B test for C. difficile, with the initial infection occurring within the past 12 months. At the time of enrolment (Day 0), participants must have completed a standard-of-care oral antibiotic therapy for their first rCDI no more than five days prior and be asymptomatic for CDI. Potential participants will sign an informed consent form at their initial visit to their doctor (visit 1) and provide a stool sample for c diff testing. Participants will only be considered 'enrolled' if their stool sample is positive for toxin B and they meet all criteria at visit 2.

Description

Inclusion Criteria:

• Able to provide signed and dated informed consent
• Males and females between 18 - 75 years old inclusive
• Documented history of first recurrent Clostridioides difficile (former Clostridium difficile) infection (rCDI), confirmed by a positive C. difficile test (Toxin A+B positive or Toxin B only), with initial infection occurring within the previous 12-months.
• Must, in accordance with standard of care practices, have completed a SOC oral antibiotic therapy for the first rCDI no more than 5 days prior to the date of enrolment (baseline visit- Day 0).
• Must not have any CDI-related symptoms when enrolled in the study at baseline (Day 0).

Exclusion Criteria:

• Current episode of CDI or delayed symptom resolution from previous recurrence, according to the physical exam and investigator assessment
• Toxin A positive, and Toxin B negative C. difficile test.
• Planned CDI recurrence treatment for the duration of the study e.g., fecal microbiome transplant, probiotics, Live Biotherapeutic Products (LBPs)
• Those who are on further antibiotic treatment following initial rCDI antibiotic therapy completion.
• Pregnant or lactating women or women who intend to become pregnant within the next 3 months.
• Subjects presenting with active diarrhoea (3 or more stools per 24-hour period) and within Bristol stool scale range of 5-7 at baseline.

• Has any significant acute or chronic coexisting health conditions that would prevent them from fulfilling the study requirements, put the Participant at risk or would confound the interpretation of the study results as judged by the investigator on the basis of medical history and routine laboratory test results.

  • Ostomized participants, parenteral nutrition users
  • Patients with active Pancreatitis
  • Active, non-controlled intestinal diseases such as IBS, IBD, Crohn's Disease, ulcerative colitis, celiac disease, or other chronic diarrheal illness
• Currently or recently taking a medication that the investigator believes would interfere with the objectives of the study or pose a safety risk or confound the interpretation of the study results.
• Individuals who, in the opinion of the investigator, are considered to be poor attendees or unlikely for any reason to be able to comply with the study.
• Participants may not be participating in other clinical studies. If the participant has previously taken part in an experimental study, the Investigator must ensure sufficient time has elapsed before entry to this study to ensure the integrity of the results.

Study Plan

How is the study designed?

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
The proportion of subjects experiencing CDI recurrence in the time period between baseline and end of study follow-up.	CDI recurrence will be defined as the development of a new episode of diarrhoea (3 or more loose stools in 24 or fewer hours) associated with a positive stool test for toxigenic C. difficile following clinical cure of the initial CDI episode.	Within the 8 week time period between baseline and end of follow-up

Collaborators and Investigators

• Sponsor: Bactolife A/S
• Investigators: Study Director: Brynjulf Mortensen, pHD, Bactolife A/S

Study record dates

Study Major Dates

• Study Start (Actual): March 1, 2026
• Primary Completion (Estimated): October 15, 2026
• Study Completion (Estimated): October 15, 2026

Study Registration Dates

• First Submitted: September 26, 2025
• First Submitted That Met QC Criteria: November 18, 2025
• First Posted (Actual): November 26, 2025

Study Record Updates

• Last Update Posted (Actual): May 28, 2026
• Last Update Submitted That Met QC Criteria: May 27, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Keywords: Clostridioides Difficile Infection; C. Diff; Clostridioides Difficile; Clostridioides Difficile Infection Recurrence; Clostridioides Difficile Recurrence; C. Diff recurrence
• Additional Relevant MeSH Terms: Infections; Gram-Positive Bacterial Infections; Bacterial Infections; Bacterial Infections and Mycoses; Clostridium Infections
• Other Study ID Numbers: AFCRO-193

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No