Fecal microbiota transplantation in patients recovering from severe pneumonia: an exploratory single-arm pilot study

Objective To explore the potential association of fecal microbiota transplantation (FMT) with gastrointestinal symptoms and intestinal dysbiosis in patients recovering from severe pneumonia. Methods A total of 15 adult patients with confirmed severe pneumonia were enrolled. One patient died and two were excluded from clinical analysis because timely blood routine data were unavailable; therefore, 12 patients were included in the clinical evaluation. FMT was administered once daily for six consecutive days via a colonoscopically placed catheter at the cecum. Clinical evaluations and blood samples were conducted at baseline and one week post-treatment. Fecal samples from six patients were collected at baseline and six months post-FMT and analyzed using metagenomic sequencing. Results After FMT treated for one week, five out of 12 patients reported symptom improvement, and nine out of 10 who had experienced fever before showed resolution within two weeks following treatment. Analysis of the gut microbiota (Beta diversity) revealed that the gut microbiota composition of recipients converged toward that of their donors post-FMT, which suggests that the improvement in symptoms might be related to FMT treatment. Specifically, at the phylum level, the relative abundance of Proteobacteria and Actinobacteria decreased, whereas Firmicutes and Bacteroidetes increased after FMT compared to baseline. At the genus level, a significant enrichment of common commensal bacteria (e.g. Phocaeicola , Parabacteroides , Lachnospira , and Phascolarctobacterium ) was observed after FMT, while pathogenic genera such as Vibrio , Streptococcus , and Enterobacter were significantly reduced. Further analysis of the functions of the microbial community revealed a significant shift in microbial functional profiles toward the donor state after FMT, marked by the upregulation of core metabolic and cellular processes and the downregulation of pathways linked to infections, which collectively indicate a functional restoration of the gut microbiome. Conclusions This study suggests that FMT may be closely related to the improvement of symptoms in patients with severe pneumonia and the restoration of intestinal microbial homeostasis. These findings suggest that FMT may be associated with therapeutic benefit and could represent a feasible rehabilitative strategy for individuals recovering from severe pneumonia.