Vowst Approved to Prevent Recurrent C. difficile Infection

Credit: Seres Therapeutics.
Vowst is expected to be available in June 2023.

The Food and Drug Administration (FDA) has approved Vowst (fecal microbiota spores, live-brpk) to prevent the recurrence of Clostridioides difficile (CDI) infection in adults 18 years of age and older following antibacterial treatment for recurrent CDI.

Vowst is a bacterial spore suspension in capsules for oral administration. It contains purified bacterial spores of multiple Firmicute species obtained from the stool of healthy human donors. The approval was supported by data from the multicenter, randomized, placebo-controlled ECOSPOR III study (ClinicalTrials.gov Identifier: NCT03183128), which included adults with a confirmed diagnosis of recurrent CDI who had a total of at least 3 episodes of CDI within 12 months.

Patients were randomly assigned 1:1 to receive 4 capsules of Vowst or placebo once daily for 3 consecutive days. The primary endpoint was CDI recurrence through 8 weeks after completion of treatment. Recurrence was defined as at least 3 unformed stools per day for 2 consecutive days with continued diarrhea until antibacterial treatment was initiated, a positive C difficile test on a stool sample determined by a toxin assay, and assessment by the investigator that the clinical condition of the participant warranted antibacterial treatment.

Results showed that at 8 weeks post treatment, the CDI recurrence rates were 12.4% (n=11/89) for Vowst-treated patients and 39.8% (n=37/93) for placebo recipients (relative risk, 0.32; 95% CI, 0.18-0.58; P <.001). Through 12 weeks after treatment, the CDI recurrence rates were 18.0% for Vowst-treated patients and 46.2% for placebo recipients (relative risk, 0.40; 95% CI, 0.24-0.65). At 24 weeks, the CDI recurrence rates were 21.3% (n=19/89) for Vowst-treated patients and 47.3% (n=44/93) for placebo recipients (relative risk, 0.46; 95% CI, 0.30–0.73).

The most common adverse reactions reported were abdominal distension (31.1%), fatigue (22.2%), constipation (14.4%), chills (11.1%), and diarrhea (10.0%).

“Today’s approval provides patients and health care providers a new way to help prevent recurrent C difficile infection,” said Peter Marks, MD, PhD, director of the FDA’s Center for Biologics Evaluation and Research. “The availability of a fecal microbiota product that can be taken orally is a significant step forward in advancing patient care and accessibility for individuals who have experienced this disease that can be potentially life-threatening.”

Vowst is supplied in a bottle containing 12 capsules. Antibacterial treatment for recurrent CDI should be completed 2 to 4 days prior to initiating treatment with Vowst.

The product is expected to be available in June 2023.


  1. Seres Therapeutics and Nestlé Health Science announce FDA approval of Vowst (fecal microbiota spores, live-brpk) for prevention of recurrence of difficile infection in adults following antibacterial treatment for recurrent CDI. News release. Seres Therapeutics and Nestlé Health Science. Accessed April 27, 2023. https://www.businesswire.com/news/home/20230426006066/en/Seres-Therapeutics-and-Nestl%C3%A9-Health-Science-Announce-FDA-Approval-of-VOWSTTM-fecal-microbiota-spores-live-brpk-for-Prevention-of-Recurrence-of-C.-difficile-Infection-in-Adults-Following-Antibacterial-Treatment-for-Recurrent-CDI.
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  3. FDA approves first orally administered fecal microbiota product for the prevention of recurrence of Clostridioides difficile News release. Food and Drug Administration. April 26, 2023. https://www.prnewswire.com/news-releases/fda-approves-first-orally-administered-fecal-microbiota-product-for-the-prevention-of-recurrence-of-clostridioides-difficile-infection-301808930.html.
  4. Vowst. Package insert. Seres Therapeutics; 2023. Accessed April 27, 2023. https://www.serestherapeutics.com/our-products/VOWST_PI.pdf.