Fecal Microbiota Transplantation Donor Screening: Is Dientamoeba fragilis a Valid Criterion for Donor Exclusion? A Longitudinal Study of a Swiss Cohort
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Introduction
Dientamoeba fragilis is a protozoan of the human digestive tract, yet its transmission and pathogenic role remain poorly understood. This study aimed to evaluate its impact on the efficacy and safety of FMT in treating recurrent Clostridioides difficile infection (rCDI).
Patients and methods
This longitudinal cohort study analyzed stool samples from FMT donors and recipients pre-treatment and at 2 and 8 weeks post-FMT. All samples were retrospectively tested using real-time PCR. Shotgun metagenomics was also performed on selected donor-recipient pairs to explore transmission. CDI cure rates, gastrointestinal adverse events (AE), and serious adverse events (SAE) were assessed prospectively.
Results
A total of 53 FMT were analysed (179 samples), with 23 (43%) derived from D. fragilis -positive donor stool (4 of 10 donors, 40%). Four of 52 recipients (18.2%), initially negative and who received treatment from positive donors, tested positive post-FMT. Shotgun metagenomics could not definitely confirm transmission due to the lack of a good reference genome. No significant differences in efficacy, AE, or SAE were observed between FMT from D. fragilis -positive versus -negative donors, even in immunocompromised patients. No SAE were attributed to FMT.
Conclusion
D. fragilis may be transmitted via FMT without clinical impact, highlighting the need to reconsider donor exclusion and aligning with growing evidence of its questionable pathogenicity.
