Changes in Intestinal Microbiota Following Combination Therapy with Fecal Microbial Transplantation and Antibiotics for Ulcerative Colitis

Background: Fecal microbiota transplantation (FMT) is a potential therapeutic approach to restore normal intestinal microbiota in patients with ulcerative colitis (UC), which is associated with dysbiosis; however, treatment efficacy remains unclear. Hence, we studied the impact of antibiotic pretreatment with amoxicillin, fosfomycin, and metronidazole (AFM therapy) and FMT versus AFM alone. Methods: AFM therapy was administered to patients for 2 weeks until 2 days before FMT. Patients' spouses or relatives were selected as donor candidates. Donor fecal samples were collected on the day of administration and transferred into the patient's colon by colonoscopy within 6 hours. Microbiome analysis was performed by 16S rRNA next-generation sequencing. Results: Patients with mild-to-severe active UC (combination-therapy group, n = 21; AFM monotherapy group, n = 20) were included. Thirty-six patients completed this assessment (combination-therapy group, n = 17; AFM monotherapy group, n = 19). A higher clinical response was observed after combination therapy compared with AFM monotherapy at 4 weeks after treatment. After the 2-week AFM therapy, the Bacteroidetes composition was nearly abolished. The Bacteroidetes proportion recovered in clinical responders at 4 weeks after FMT was not observed in the AFM monotherapy group. Persistent antimicrobial-associated dysbiosis found in the AFM monotherapy group was reversed by FMT. The recovery rate of Bacteroidetes at 4 weeks after FMT correlated with endoscopic severity. Conclusions: FMT following antimicrobial bowel cleansing synergistically contributes to the recovery of the Bacteroidetes composition, which is associated with clinical response and UC severity. Thus, this therapeutic protocol may be useful for managing UC.