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.)

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.

Participants will be included in the study if they meet all of the following criteria

At the time of screening:

• Able to provide signed and dated informed consent
• Males and females from the age of 18 and above
• Planned or already ongoing SoC antibiotic treatment for diagnosed Clostridiodides difficile infection (CDI). All types of diagnosis/testing algorithms, and antibiotic taper regimes acceptable.
• Documented history of, minimum one previous CDI episode occurring within the last 12 months.

At the Time of Baseline Visit:

- Have completed the antibiotic treatment regime for the current CDI, a maximum of 5 days prior to the baseline visit

Exclusion criteria

Participants will be excluded from the study if they meet any of the following criteria:

At the time of screening:

• Planned CDI recurrence treatment for the planned 8-week duration of study participation (I.e., Fecal microbiome transplant, Rebyota, Vowst, Live Biotherapeutic Products (LBPs), probiotics etc)
• Pregnant or lactating women or women who intend/wish to become pregnant in the time period in between screening and visit 4
• 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. I.e.: 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 study attendees or unlikely for any reason to be able to comply with the study.
• Participants may not be participating in other clinical studies, or planning to do so during participating in the present study. 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.

At the time of baseline visit:

• Lack of CDI symptom resolution following the SoC antibiotic regime. I.e. still active diarrhoea (3 or more stools per 24-hour period) and within Bristol stool scale range of 5-7 at baseline.
• Those who are on, or during study participation plan to go on, antibiotic treatment for any reason.