Positive results have been released from a Phase 1b/2 trial testing the efficacy of a microbiome-based, oral therapeutic drug to treat recurrent C. difficile infection (CDI); the most common hospital-acquired infection in the US.

The therapeutic drug is called SER-109, it showed a 97.6% rate of effectiveness in the study, which was conducted by researchers at the Massachusetts General Hospital (MGH). Although the study did not contain a control group, its efficacy rate is significantly greater than a previous an open-label antibiotic trial which demonstrated 23-31% efficacy rates. Another option open to patients with C. difficile infection is a fecal microbiota transplant (FMT), however it’s not FDA-approved and requires a patient’s informed consent. A previous FMT trial achieved 81% efficacy in halting relapses.

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“This oral microbial preparation that contains a small fraction of the total microbiome works as well as, if not better than, FMT,” said Elizabeth Hohmann, MD, senior author of the study. SER-109 is prepared from stool samples from prescreened healthy donors and contains bacterial spores, a dormant form that only becomes active in appropriate environments like the lower gastrointestinal tract. Thirty volunteers participated in the study, after taking SER-109, 26 had no recurrence of C. difficile-positive diarrhea during the 8 week study period. Four patients experienced C. difficile-positive diarrhea during the study but this was temporary, and they were free of infection at the end of the 8-week study. One patient dropped out of the study when they experienced recurrence.

At the end of the study, microbial populations revealed not only establishment of the species contained in the SER-109 capsule but also a return of other beneficial species not found in the product.  A Phase 2 randomized, double-blind, placebo-controlled trial of SER-109 is currently underway at the MGH and approximately 36 others sites across the US.

For more information visit the MGH or ClinicalTrails.gov.