Forty-nine pediatric patients who underwent FMT at Shanghai Children’s Hospital from November 2013 to February 2018 were recruited into our retrospective analysis. These patients included children with the diagnosis of recurrent CDI (with or without inflammatory bowel disease), chronic intractable diarrhea, functional gastrointestinal disorder, metabolic syndrome, non-alcoholic steatohepatitis, severe eczema, systemic juvenile rheumatoid arthritis (sJIA), hemophagocytic lymphohistiocytosis with Epstein-Barr virus (EBV) infection, and Okuda syndrome with severe constipation (Table 1). Written informed consent was obtained from parents or legal guardians of all pediatric subjects. This study was approved by the Regional Ethical Review Board in Shanghai Children’s Hospital (2014RY015-E02).

Donors aged between 18 to 50 without smoking, alcohol, or other bad habits or digestive symptoms were provided from rigorously screened healthy donors from a universal stool bank (OpenBiome)[12]. Eligible donors underwent serological testing for HIV type 1 and 2 antibody (Ab), hepatitis A total Ab, hepatitis B surface antigen (Ag), hepatitis B surface Ab, hepatitis B core Ab (IgM and IgG), hepatitis C Ab, syphilis Ab, CMV IgM, EBV-DNA, human parvovirus B19 IgM, TORCH, T-SPOT, hepatic and renal function, routine blood parameters, and lymphatic subgroup analysis. The participants also underwent stool testing with bacterial culture for enteric pathogens (Escherichia coli 0157, Salmonella, Shigella, Yersinia, Campylobacter, Staphylococcus aureus, Vibrio parahaemolyticus, and Vibrio cholerae), parasitic ovum and parasites; C. difficile toxin A/B; fecal Giardia, Cryptosporidium, and Helicobacter pylori antigens; and Norovirus and Rotavirus through enzyme immunoassays. The 16S RNA bacterial sequence was tested if necessary. Other tests included abdominal ultrasound scan and C13 breath test.

Fresh stool from each donor was collected and blended using 200-250 mL sterilized saline per 150 g stool at high speed for 2-3 min. The stool suspension was filtered with two layers of medical gauze to remove large particles. Stool filtrate was drawn into 50 mL syringes for immediate FMT use or collected in 50 mL tubes and frozen at -80 °C for further use[13].

The bacterial liquid was resuscitated and transferred into the patients’ digestive tract. The route of administration varied and included nasojejunal tube, nasogastric tube, and enema. The time of FMT infusion was divided into single infusion (1 d) or multiple infusions (2-3 d continuously). Five millilitres of bacterial liquid per kilogram weight of the patient was used. The dose was adjusted by the age or weight of patients, and when the patient’s weight was more than 50 kg, the dose for adults was used[14]. The patients fasted for at least 4 h before FMT, and infusion was slowly administered through a tube. After the infusion procedure, patients were asked to keep the same position (>30° semireclining position or hip-up position) for at least 2 h[15].

AEs were evaluated and assessed according to clinical manifestation, laboratory tests, and follow-up period. All AEs were divided into short-term (48 h post-FMT) and long-term (3 mo)[16,17]. The short-term AEs were defined as any untoward medical occurrence that did not exist before FMT or syndrome deterioration in a patient to whom FMT was administered. Short-term AEs could be clinically significant changes from baseline physical examination, laboratory tests, or other diagnostic investigations, complications related to the procedure used to administer FMT, or new events or pre-existing conditions that became aggravated or worsened in severity or frequency within 48 h post-FMT. The potential long-term AEs under our supervision included infection due to unrecognized infectious agents, chronic diseases based on gut microbiota alteration, restriction of growth, and changes in behavior. The intensity and severity of AEs with FMT followed the Common Terminology Criteria for Adverse Events (version 3.0), in which severe AEs (SAEs) were any adverse experience occurring during or after FMT beyond mild or moderate AEs. AEs and SAEs were determined to be related or unrelated[7].

IBM SPSS Statistics 20 was used for statistical analyses. The independent factors were analyzed by the Pearson/Fisher χ² test or rank sum test, while the between-group variance was determined by the Tukey’s HSD test. Values of P < 0.05 were considered statistically significant. The significant independent factors and risk ratio with 95% confidence interval (CI) were assessed by multivariate logistic regression analysis.

The characteristics of all patients and donors are listed in Table 1. Twenty-seven male and 22 female subjects, with a mean age 68.1 mo (range 4 to 193 mo) were enrolled in this cohort. Their average follow-up time after the first FMT was 23.1 mo. The 49 subjects were divided into two major groups (gastrointestinal disorders and nongastrointestinal disorders). Fifteen patients were diagnosed as being immunodeficient (6 primary immunodeficiency and 9 inflammatory bowel disease (IBD) patients with immunosuppressive agent treatment) after FMT. Twenty patients accepted FMT once, while 29 patients had 2-11 rounds of FMT. There were 30 donors (11 of them were male), whose mean age was 32.8 years old, including 14 patients’ family members (12 of them were parents and 2 of them were sisters) and 16 volunteers.

All short-term AEs were self-limited and symptom-free within 48 h. In total, 38.78% (19/49) of patients had AEs after FMT. Six of them had multiple AEs (2-4), and 10 of 15 immunodeficient patients had AEs. The number of AEs by different category is listed in Table 2. The total incidence of short-term AEs was 26.32% (30/114) (Table 3). The most common AEs were abdominal pain (8/114, 7.02%), diarrhea (7/114, 6.14%), fever (6/114, 5.26%), and vomiting (6/114, 5.26%). The incidence of upper gastrointestinal symptoms such as nausea, sore throat, and vomiting was 7.89% (9/114). Lower gastrointestinal symptoms such as diarrhea, abdominal pain, and mucoid stool were observed in 14.04% (16/114). Other manifestations, such as fever, appetite decrease, and chest distress, occurred in 7.02% (8/114). In all nasogastric tube ways, 80% (4/5) of AEs were vomiting and the other AEs were appetite decrease with abdominal pain. After enema, 66.7% (4/6) of AEs were the changes of stool (3 diarrhea and 1 mucoid stool), which might indicate that the different gastrointestinal symptoms were related to different routes of administration. Out of all FMT treatments, severe AEs occurred in two cases. One UC case (PUCAI = 45) had 60 mL of blood stool 6 h post-FMT. Another UC case (PUCAI = 55) developed gastric stricture accompanied by nausea and hematemesis (30 mL) 4 h after FMT.

No relevant long-term AEs happened during 3-mo follow-up. One primary immunodeficiency patient was treated by FMT for chronic intractable diarrhea. The patient died due to sepsis and liver failure 4 wk after FMT. All-cause mortality was 2.04%.

Comparing either each individual or every FMT, the AE occurrence had no significant difference (χ² test, P = 0.252, data not shown). Ten of 15 immunodeficient patients showed AEs, compared with 9 of 34 patients with normal immune function, which indicated that immunodeficient patients might have greater risk than others (χ² test, P = 0.008, data not shown). All potential factors influencing AEs, such as gender, age, time of FMT infusion, route of administration, disease type, immune function state, and donor relative genetic background, were investigated through the χ² test. As independent factors, only age (rank sum test, P = 0.006, data not shown) and immune state (χ² test, P = 0.002) had significant effects on AE occurrence (Table 4). Therefore, we divided the patients into different age groups to determine how age affected AEs. The data showed that four age groups had a difference in AE rate (χ² test, P = 0.02), and age more than 72 mo was associated with more AEs than age 13 to 36 mo (Tukey’s HSD test between different groups, P = 0.04, data not shown). The reason why they had different AE rates might be the bias that older children could give a more accurate description of uncomfortable symptoms. Furthermore, we analyzed age groups and immune states by multivariate logistics regression analysis (Table 3). The results showed that immune state was an independent risk factor for AE occurrence (P = 0.035), and the risk ratio in immunodeficient patients was 3.105 (95%CI: 1.080-8.923).

Fecal microbiota transplantation (FMT) is the administration of fecal bacterial liquid from healthy donors to a recipient’s digestive tract, which is recommended as a therapeutic method for recurrent Clostridium difficile infection (CDI). Many clinical trials focusing on different diseases are in progress. To date, scarce research and long-term follow-up data have been conducted on FMT in children or on the proper guidelines. Our center first performed FMT to treat a 13-month-old boy with severe CDI in 2013. Until February 2018, our center had performed 114 pediatric FMT procedures in 49 subjects. We here retrospectively evaluated the safety of these procedures and analyzed the adverse events (AEs).

To investigate the safety of FMT in children.

To evaluate the adverse events occurring during and after the procedure of FMT.

Forty-nine patients at Shanghai Children’s Hospital from November 2013 to February 2018 were recruited into our retrospective analysis. All FMT processes followed uniform standards. AEs related to FMT were divided into short-term (48 h post-FMT) and long-term (3 mo). All potential factors influencing AEs, such as gender, age, time of FMT infusion, route of administration, disease type, immune function state, and donor relative genetic background, were analyzed as independent factors. The significant independent factors and risk ratio with 95% confidence interval (CI) were assessed by multivariate logistic regression analysis.

Forty-nine patients (mean age 68.1 mo, range 4 to 193) were recruited. Their average follow-up time after the first FMT was 23.1 mo. The incidence of short-term AEs was 26.32% (30/114). The most common short-term AEs were abdominal pain, diarrhea, fever, and vomiting, which were all self-limited and symptom-free within 48 h. Two severe AEs occurred, and one patient died in the fourth week after FMT. All-cause mortality was 2.04%. As independent factors, age (P = 0.006) and immune state (P = 0.002) had significant effects. Age greater than 72 mo seemed to be correlated with more AEs than age 13 to 36 mo (P = 0.04). In multivariate logistic regression analysis, immune state was an independent risk factor for AE occurrence (P = 0.035), and the risk ratio in immunodeficient patients was 3.105 (95%CI: 1.080-8.923).

FMT was proven to be tolerated and safe in children. However, we need to be more cautious with immunodeficient patients. The effect on children’s long-term health is unpredictable.

FMT was well tolerated and safe in children, while more data for immunodeficient pediatric patients are required.