Fecal microbiota transplantation (FMT) is an investigational treatment designed to correct dysbiosis in the gut by administration of feces from a healthy volunteer. The gut microbiota contributes to harvest of energy from food, and changes in the gut microbiome may be associated with some bowel diseases [1]. Ulcerative colitis (UC) is a chronic relapsing inflammatory disorder of the colon. Although the cause remains unknown, immunological abnormalities triggered by genetic and environmental factors are thought to play an important role in its pathogenesis [2]. Current medical treatments for UC include aminosalicylates, thioprines, corticosteroids, tumor necrosis factor-modulating agents, and other immunosuppressives [3]. Some patients with UC require colectomy because of poor response to these treatments. Recently a randomized control study has reported that FMT can have therapeutic benefits for adult patients with UC [4]. However, it is still unclear whether FMT for children with UC is effective or hazardous.

Here we report a three-year-old girl with refractory severe UC for whom colectomy ultimately became necessary after sequential FMT proved ineffective. Fecal analysis revealed that the donor's microbiota had failed to become established in the gut of the patient. In this case, the severity of the UC and/or the timing of FMT may have affected the outcome.

A three-year-old girl presented with a 3-month history of hematochezia that had gradually worsened. She was diagnosed as having severe active UC endoscopically and histologically, and treatment with aminosalicylates and steroids was started. Two weeks later she was referred to our hospital because of steroid refractoriness. She discharged a large volume of bloody diarrhea more than 20 times per day, and suffered marked abdominal pain, worsening fatigue and weight loss (from 12 kg at the time of onset to 10 kg). Blood examination demonstrated anemia (hemoglobin, 8.4 g/dL), leukocytosis (white blood cells, 39,500/µL), and elevated values of inflammatory markers (erythrocyte sedimentation rate, 16 mm/h,; C-reactive protein, 2.2 mg/dL). Abdominal radiography showed a paucity of bowel gas in the entire colon. Stool cultures and stool tests for toxins A and B all gave negative results. The Pediatric Ulcerative Colitis Activity Index (PUCAI) score was 85 (i.e., the maximum score possible).

For re-evaluation the patient underwent esophagogastroduodenoscopy and colonoscopy. Endoscopy revealed severe diffuse and continuous mucosal inflammation with superficial ulcers and erythema involving the entire colon (Fig. 1A), whereas the upper gastro-intestine and terminal ileum were intact. The histological features were compatible with UC, including acute colonic inflammation with crypt abscesses throughout the colon (Fig. 1B), without abnormalities in the esophagus, stomach, duodenum, and terminal ileum.

Because patients with very early-onset inflammatory bowel disease, diagnosed ≤5 years of age, frequently present with a severe phenotype and carry variants in genes associated with immunodeficiency, we analyzed the whole exome sequence of the patient and her parents using genomic DNA extracted from lymphocytes. However, no significant variants including the genes related to immunodeficiency were detected.

As the data from these investigations led us to reconfirm that the patient had severe UC, in addition to mesalazine and intravenous prednisolone, we administered parenteral nutrition from a central venous catheter and started the patient on intravenous cyclosporine A. However, these treatments did not alleviate the symptoms. We started the patient on infliximab at 6 mg/kg and scheduled further infliximab infusions, two and six weeks later. During this period we switched intravenous prednisolone and cyclosporine A to oral tacrolimus treatment. Since her daily bowel movements with bloody stools showed no significant change, and she required blood transfusions repeatedly because of anemia, we discontinued the infliximab infusions. Neither leukocytapheresis nor granulocytapheresis was indicated because of the patient's small body size. During the course of the above treatments, the patient received probiotic therapy with Clostridium butyricum (Miya BM; Miyarisan Pharmaceutical Co., Ltd., Tokyo, Japan). This probiotic is used safely in Japan for over 40 years. Recently, it has been reported that C. butyricum may induce interleukin-10-producing immunoregulatory macrophages and have potential as a safer therapeutic option for gut inflammatory diseases [5].

We discussed the available options with the patient's mother and guardians, and these included colectomy and unconventional medical therapy including FMT. They decided that FMT should be attempted before opting for colectomy. After obtaining permission from our institutional Bioethics Committee (approved number: Shin 15-02), written informed consent for FMT was obtained from the patient's mother and guardians.

The clinical course of this child illustrated two notable issues: first, that a pediatric patient with severe refractory active UC may not respond to FMT, and second, therapy using both a nasoduodenal tube and retention enema has been tolerated in such a young child, although transient fever and abdominal pain developed in this case.

In the present pediatric patient, comparison of the fecal microbiota composition between the donor and recipient revealed failure of the patient's intestine to retain the donor microbiota, despite the use of sequential FMT. One reason for the poor response might have been the severity of the disease. Previous reports of successful outcomes associated with FMT for UC involved patients with relatively mild disease [41112]. In contrast, our patient had a short disease duration of seven months, and had received several different immunosuppressive drugs, including steroids, cyclosporin A, tacrolimus, and infliximab, reflecting the progressive course of the illness. The stratification between the outer mucus layer of the large intestine and the luminal contents is important from the standpoint of host microbial mutualism [13]. In severe UC cases, the outer layer of mucus might be influenced by a decreased number of intestinal goblet cells and increased intestinal motility. In our patient, the pathohistological features of the removed colon demonstrated a marked decrease in the number of crypts in the lamina propria and a severely damaged epithelium, both of which suggested a marked decrease of mucus in the outer layer. The patient also had hyperactive bowel movement. Thus, the donor's microbiota would have merely passed through the recipient's gut following the sequential FMTs, thus accounting for the discrepancy of the intestinal microbiota profiles between the donor and the patient after FMT. Angelberger et al. [14] reported that out of five adult patients who underwent FMT because of moderately to severely active UC, only one showed a positive clinical response after 12 weeks. Their findings tend to support this interpretation. Therefore, any pediatric patient with UC who has achieved remission through conventional medical therapy, or who has mild disease, might be a better candidate for FMT.

Another possible reason for the poor response might have been related to stool preparation and the method of administration for FMT. Vandenplas et al. [1516] reported a transient positive response to FMT in a child who presented with early onset of an UC-like condition. Although they administered approximately 10 mL/kg of a 50% suspended fecal slurry, we decided to inject 25 mL/kg of a 20% preparation according to the FMT workgroup recommendations [6]. They administered the donor stool preparation using colonoscopy and a nasoduodenal tube. Endoscopic administration into the cecum is thought to be more effective than use of a retention enema; however, this patient was considered incapable of tolerating endoscopic administration. On the other hand, donor stool infusion through a nasoduodenal tube is thought to be more effective than use of a nasogastric tube because the former route means that microorganisms are unaffected by gastric acid. Therefore, we infused our stool preparation via a nasoduodenal tube, as reported by Vandenplas et al. [15].

Although FMT delivered via both a nasoduodenal tube and retention enema had been tolerated, transient fever and abdominal pain developed. This suggests a temporary systemic immune response to FMT in children with UC. Similarly, Vermeire et al. [17] reported fever and abdominal tenderness in patients with Crohn's disease who underwent FMT. Vandenplas et al. [15] also reported transient symptoms including profuse sweating, vomiting, paleness, tachycardia, and fever. Bacteremia following FMT has also been reported [18], but in our patient the transient immune response was apparently not caused by bacteremia, as blood cultures were negative, although translocation of bacterial compounds such as lipopolysaccharide through disruption of the intestinal mucosal barrier caused by severe inflammation cannot be excluded [14].

FMT for severe refractory active UC may be challenging, and many unresolved issues remain, such as selection of the ideal donor, the most effective preparation method, the most ideal route of administration, and the most effective schedule or duration of FMT for inducing and maintaining a positive clinical response. Further investigation is needed to determine the optimal patient and donor selection, and the ideal FMT protocol for UC.