Fecal microbiota spores, live-brpk (previously SER-109) significantly reduce the risk for recurrent Clostridioides difficile infection (CDI) when compared with placebo, irrespective of patient characteristics, concomitant medications, and comorbidities. These study results were published in Clinical Infectious Diseases.

An increased risk for CDI recurrence has been strongly associated with comorbidities such as cardiovascular disease, immunosuppression, and kidney failure, among others. However, patients with comorbidities are often excluded from clinical trials, resulting in a limited understanding of the best treatment course for this population.

To bridge this knowledge gap, researchers conducted a phase 3, double-blinded, placebo-controlled, randomized trial (ECOSPOR III) to investigate the rate of CDI recurrence through week 8 among patients (N=109; 59.9% women; 56.6% aged >65 years) randomly assigned to receive fecal microbiota spores, live-brpk (intervention) or placebo. Results of this trial demonstrated the superiority of the intervention compared with that of placebo.

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In this post hoc exploratory analysis, researchers assessed the rate of CDI recurrence among intervention and placebo recipients who were divided into subgroups based on comorbidities and other CDI-related risk factors.

The relative risk for CDI recurrence at week 8 was lower among intervention vs placebo recipients across all high-risk subgroups, including those based on age, sex, number of previous CDI episodes, baseline creatinine clearance, non-CDI antibiotic use, baseline acid-suppressing medication use, and Charlson comorbidity index (CCI) score categories (0, 1-2, 3-4, and ≥5).

Among patients grouped by CCI score category, placebo recipients with a CCI score of 0 had a CDI recurrence rate of 20%, which increased to 45.7% among those with a score of at least 5. Overall, CDI recurrence rates were lower among intervention vs placebo recipients across all CCI score categories, ranging from 0% to 20%.

Among patients grouped by baseline acid-suppressing medication use, CDI recurrence rates among placebo recipients were higher for those with vs without baseline use (48.8% vs 32.7%). In contrast, CDI recurrence rates were low among intervention recipients regardless of baseline acid-suppressing medication use (9.1% vs 14.3%, respectively).

Limitations of this study include the small sample size, the inability to rule out potential confounders within each subgroup, and the low number of patients with active inflammatory bowel disease.

According to the researchers, “Since most risk factors for CDI are nonmodifiable, these efficacy data help to inform the potential benefit of VOS in vulnerable patients with recurrent infection.”

Disclosures: Multiple study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see original source for full list of disclosures.


Berenson CS, Lashner B, Korman L, et al. Prevalence of comorbid factors in patients with recurrent Clostridioides difficile infection in ECOSPOR III, a randomized trial of an oral microbiota-based therapeutic.  Clin Infect Dis. Published online, August 4, 2023. doi:10.1093/cid/ciad448

This article originally appeared on Infectious Disease Advisor