Biomarkers for Successful Faecal Microbiota Transplantation in Recurrent Clostridioides difficile Infection
Faecal microbiota transplantation (FMT) is used to treat recurrent Clostridioides difficile infection (R-CDI). We sought potential biomarkers of the success of FMT by using freeze-dried capsules and analyzing changes in gut microbiota and calprotectin levels.  We conducted a prospective study of patients who underwent oral FMT (single dose of 4-5 capsules) for R-CDI (January 2018 to December 2022). The V4 region of the 16S rRNA gene was sequenced. Sequencing data analysis and statistical analysis were performed using MOTHUR and R. Ninety-seven patients underwent FMT (105 FMTs). We processed 221 samples (21 donors, 24 capsule contents, and 176 patient faecal samples [39 at diagnosis, 63 pre-FMT, and 74 post-FMT]). FMT was very successful (85.1% of cases). The abundance of Bacteroides, Ruminococcus, Megamonas, and some Prevotella OTUs was higher in 100%-effective capsules than in less effective capsules. FMT engraftment was 95% in patients with favourable outcomes and 62% in those with recurrences (p=0.006). A negative correlation was recorded between calprotectin levels and specific genera, indicating a favourable outcome. We found differences in the evolution of faecal microbiota, metabolic pathways, engraftment, and inflammation markers (such as calprotectin) between patients who received FMT with varying outcomes and identified potential biomarkers of successful FMT.