Effects of fecal microbiota transplantation and probiotics on the gut microbiome in antibiotic-treated septic patients: A pilot randomized controlled trial.

Broad-spectrum antibiotics, essential for sepsis management in critically ill patients, cause significant gut dysbiosis. Restoring gut microbiota may improve outcomes, but the efficacy of interventions like fecal microbiota transplantation (FMT) and probiotics in this setting remains underexplored. This study aims to evaluate the feasibility and potential efficacy of FMT versus probiotics on gut microbiome restoration and inflammatory markers in critically ill, antibiotic-treated sepsis patients. In this single-center, prospective, exploratory pilot RCT, 40 sepsis patients were were randomized 2:1:1 to: Control (n = 20, antibiotics treatment), Probiotics (n = 10, antibiotics treatment combined one week of probiotics), and FMT (n = 10, antibiotics treatment combined one week of FMT) groups. Gut microbiota composition was analyzed using 16S rDNA sequencing, and clinical inflammatory markers were assessed at baseline, one week, and two weeks post-treatment. FMT significantly mitigated antibiotic-induced reductions in microbial diversity. At 2 weeks, the FMT group exhibited higher alpha-diversity (Chao1 index, p = 0.0125; Shannon/Simpson trends p = 0.06) compared to Control and Probiotics groups. FMT increased beneficial Bacteroides abundance and reduced Enterobacteriaceae. BugBase analysis revealed FMT significantly lowered pathogenic potential of gut microbiota (p = 0.021). Donor-recipient analysis showed FMT shifted recipient microbiomes toward donor enterotype. This study provides preliminary evidence that FMT, but not the probiotic regimen, effectively restores gut microbiome diversity and composition, reduces pathogenic potential, and may improve clinical outcomes in critically ill sepsis patients after broad-spectrum antibiotics. This study was registered on ClinicalTrials.gov (NCT05578196).