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Clinical Trials

Due to the nature of Clostridium difficile infections, particularly the high recurrence rate following standard treatments, participating in a clinical trial may be an option for sufferers who don’t respond to antibiotics. Some clinical trials focus on developing vaccines and other preventatives. Those trials often need healthy volunteers without a CDI to participate. The following are large, active trials focused on C. diff treatment and prevention. For smaller scale and local trials, please visit our In Your State page and search for ones near you.

What is a Clinical Trial?

A clinical trial is a research study that using human volunteers that is intended to add to medical knowledge. Clinical trials can vary in size from a single location in one country to multiple locations in multiple countries. Some research studies may determine if an investigational product can be administered to children or special populations. Some studies assess a drug’s long-term effectiveness and its impact on the quality of a person’s life.

All studies of a drug, biological product, or medical device regulated by FDA must be reviewed, approved, and monitored by an institutional review board (IRB) or Ethics Committee (EC). All clinical trials are conducted using Principles of Good Clinical Practice (GCP) and are under the supervision of an IRB or EC whose mission is to ensure the safety and welfare of study participants. To learn more about clinical trials, please visit Clinical



Crestone is developing a novel antibiotic known as CRS3123 for treatment of C. difficile infection, or CDI. In preclinical (early) studies CRS3123 has demonstrated that it quickly halts production of C. difficile toxin and spores via a new mechanism of action. In Phase 1 human clinical trials it caused minimal disruption of other, normal gut bacteria. In this Phase 2 study sponsored by NIAID (NIH), Crestone will test two different doses of CRS3123 compared to a standard antibiotic treatment for this infection called vancomycin.

If enrolled, subjects will receive either, 400 mg or 800 mg of CRS3123 or vancomycin for 10 days. Doses will be taken by mouth, every 6 hours. Neither subjects nor study healthcare providers will know which drug is being administered. Then subjects will be followed for an additional 60 days, resulting in about eight outpatient study visits over 70 days. Participants will receive study-related medication and exams at no cost and may be reimbursed for travel expenses for study visits.

The study will enroll subjects 18 or older who have a primary episode or first recurrence of CDI, including diarrhea in the last 24 hours and a positive C. difficile toxin test on a stool sample. They may not participate if they have had more than one CDI episode in the last three months (or one that was not initially responsive to vancomycin), or two CDI episodes in the past twelve months. Pregnant or breastfeeding women may not participate in this study, and other entry criteria apply. Study physicians will determine eligibility and then request subjects’ consent to participate.

This study is currently recruiting in the following areas: Sacramento, CA; Lancaster, CA; Calgary, AB CANADA; London, ON CANADA; St. Petersburg, FL; Miami Lakes, FL; Pompano Beach, FL; Miami, FL; Doral, FL; Idaho Falls, ID; Shreveport, LA; Rochester, MN; Omaha, NE; Mentor, OH; Toledo, OH; Uniontown, PA; Union City, TN; San Antonio, TX; Cedar Park, TX; Houston, TX; Seattle, WA.

To learn more, please visit Crestone’s website CRESTONE C-DIFF Study or to join the study please contact Vicki J Abbas, BSN RN at or by phone at 303-263-4646.

Vedanta Biosciences

Vedanta Biosciences, Inc. is dedicated to finding treatments for patients with serious infections and immune diseases. VE303 is Vedanta’s investigational treatment for patients with recurrent C. difficile infections (CDI).  VE303 is a preparation of eight different types of bacteria grown in clean conditions, dried, powdered and put into capsules to be administered orally.  The bacteria are reactivated once they reach the intestines. The 8 bacteria were selected for their ability to provide resistance against C. difficile.   In contrast to fecal transplants, which rely on direct sourcing of fecal donor material of inconsistent composition, VE303 is manufactured from pure cell banks that yield a product of uniform composition, free of viruses and uncharacterized bacteria.

The results of Phase 1 study of VE303 in healthy volunteers showed both rapid expansion of protective VE303 bacteria in the gut and accelerated recovery to a healthy microbiome after disruption to the normal microbiome in the gut caused by antibiotics. Based on these positive Phase 1 results, Vedanta is now evaluating VE303 in a Phase 2 clinical study (CONSORTIUM) in participants with recurrent CDI to see if it can prevent future CDI recurrences by restoring the intestinal bacteria to a healthy state.

Up to 146 participants over the age of 18 years old with any number of recurrent CDI episodes including the current episode will be enrolled in the CONSORTIUM study. Two out of every three study patients will receive VE303, and one out of every three study participants will receive the placebo study treatment (2:1 randomization) upon completion of standard antibiotic treatment. CONSORTIUM’s primary study objective will be to determine the safety and efficacy of VE303 at preventing CDI recurrence within 8 weeks of completion of antibiotic treatment.

CONSORTIUM is currently recruiting participants across North America (U.S. and Canada). If you or someone close to you has been diagnosed with recurrent CDI, you may be eligible to take part in the study. To learn more about the study and to locate a study site near you, please visit:

National Institute of Allergy and Infectious Diseases (NIAID) 

National Institute of Allergy and Infectious Diseases (NIAID) is conducting a multi-center, randomized, placebo controlled, partially blinded trial comparing the safety and efficacy of fecal microbiota transplantation versus placebo both delivered by rectal enema in subjects 18 years of age or older with recurrent Clostridium difficile Associated Disease (CDAD). 162 male or female subjects will be enrolled in the study. Enrolled subjects will be randomized at each site to receive either FMT by enema or placebo by enema in a 2:1 ratio. Study duration is 4 years, subject participation duration is approximately 3 years. Primary study objectives are to: 1) evaluate the safety of FMT(s) delivered by enema vs. placebo delivered by enema, 2) determine efficacy of FMT delivered by enema vs. placebo delivered by enema.

For more information, please follow this link to

Vaccine & Preventatives

None at this time.