Fecal Microbiome, Metabolites, and Stem Cell Transplant Outcomes: A Single-Center Pilot StudyOriginal paper
Karen Pendergrass is a microbiome researcher specializing in microbiome-targeted interventions (MBTIs). She systematically analyzes scientific literature to identify microbial patterns, develop hypotheses, and validate interventions. As the founder of the Microbiome Signatures Database, she bridges microbiome research with clinical practice. In 2012, based on her own investigative research, she became the first documented case of FMT for Celiac Disease, four years before the first published case study.
Read MoreWhat was studied?
This pilot study tested whether fecal microbial metabolites could serve as practical surrogates for gut microbiome composition after stem cell transplant. Standard 16S sequencing is too slow for clinical decisions. Researchers measured fecal indole and butyrate by liquid chromatography tandem mass spectrometry. Gut microbiota were profiled by 16S ribosomal RNA V4 sequencing. Metabolite and diversity measures were correlated with transplant outcomes including graft-versus-host disease, infection, and survival.
Who was studied?
The cohort was 44 adult hematopoietic stem cell transplant recipients at a Texas cancer center, with 6 additional enrollees withdrawing. Most had acute myeloid leukemia or myelodysplastic syndrome (65.9%). Longitudinal stool samples (451 total) were collected from before transplant through day 100. Eighteen healthy adult volunteers gave one-time control samples. Median recipient age was 58.5 years. Most received myeloablative conditioning and matched unrelated donor grafts.
What were the most important findings?
Both fecal indole and butyrate correlated with the Shannon diversity index at baseline (P = 0.02 and P = 0.002) and after transplant (P = 0.006 and less than 0.001). High-butyrate samples were enriched for Clostridiales; high-indole samples also for Bacteroidales. Lower diversity at engraftment was linked to more acute intestinal graft-versus-host disease (P = 0.02) and transplant-related deaths (P = 0.03). Patients who developed bloodstream infection within 30 days had significantly lower fecal butyrate at week 2 (P = 0.03).
What are the greatest implications of this study?
The findings suggest fecal butyrate and indole could act as fast surrogate markers for gut microbial diversity and specific taxa after transplant. This could sidestep the delays of sequencing in the clinic. Low butyrate shortly after transplant flagged patients at risk of bloodstream infection, hinting that diet or prebiotic approaches might help. Metabolites were not significantly tied to graft-versus-host disease or overall survival, likely due to small size. Larger multi-center studies are needed before clinical use.