Compositional Changes in the Gut Microbiota of Responders and Non-responders to Probiotic Treatment Among Patients With Diarrhea-predominant Irritable Bowel Syndrome: A Post Hoc Analysis of a Randomized Clinical TrialOriginal 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 post hoc analysis of a randomized, double-blind, placebo-controlled trial examined fecal microbiota in patients with diarrhea-predominant irritable bowel syndrome (IBS-D). It compared responders and non-responders to an 8-week course of a multi-strain probiotic (Lactobacillus acidophilus, L. plantarum, L. rhamnosus, Bifidobacterium breve, B. lactis, B. longum, and Streptococcus thermophilus).
How was it studied?
Fifty patients with IBS-D were randomized to probiotic or placebo groups, with stool collected before and after 8 weeks of treatment. Fecal microbiota were profiled by Illumina MiSeq 16S sequencing and analyzed with the EzBioCloud pipeline, using LEfSe to identify biomarkers of treatment response.
What did they find?
Alpha and beta diversity did not differ between responders and non-responders. Proteobacteria and Bacteroides abundance fell after probiotic treatment, while Bifidobacterium bifidum, Pediococcus acidilactici, and Enterococcus faecium rose relative to placebo. Enterococcus faecalis and Lactococcus lactis marked non-responders, and Fusicatenibacter saccharivorans increased specifically in responders.
Why it matters
E. faecalis and L. lactis abundance before treatment may help predict which IBS-D patients will not respond to this probiotic combination. Fusicatenibacter saccharivorans, a short-chain fatty acid producer, emerges as a candidate marker and possible mechanistic link to symptom improvement.