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NCT Number: NCT07371013

Fecal Microbiota Transplantation in Children With Autism Spectrum Disorder and Gastrointestinal Symptoms

The aim of the study is to evaluate the effectiveness and safety of fecal microbiota transplantation (FMT) in reducing gastrointestinal (GI) and behavioral symptoms in children with autism spectrum disorder (ASD).

Children with ASD often experience GI problems such as constipation, diarrhea, and abdominal pain. These symptoms can negatively affect their daily life and behavior. Recent research suggests that the gut microbiota-the community of bacteria and other microorganisms living in the intestines-plays an important role in digestion, immunity, and communication with the brain through the gut-brain axis. Modifying the gut microbiota may help improve GI symptoms and possibly behavioral functioning.

FMT involves giving a preparation containing gut microbiota from a healthy donor after bowel cleansing. The product used in this study is MBiotix HBI Caps, produced by Human Biome Institute. A placebo (inactive substance) will also be used for comparison. Both will be given as frozen oral capsules that look identical.

20 children aged 6-12 years will take part. Participants will be randomly assigned to receive either the microbiota preparation or placebo. The study includes several visits over about 6 months. Before the first dose, every child will undergo bowel cleansing with a special preparation (Polyethylene Glycol, PEG). During the study, participants will be asked to keep a symptom diary, complete questionnaires, and record child's diet. Biological samples (stool, urine, saliva) will be collected at specific time points for analysis. Every child will also be assessed by a psychologist before the study begins and again during the study using standardized tools (Autism Diagnostic Observation Schedule, Second Edition, ADOS-2) to evaluate behavioral functioning and quality of life.

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Key information

Conditions

Autism Spectrum Disorder Autistic Disorder Child Development Disorders, Pervasive Gastrointestinal Symptoms Mental Disorders Neurodevelopmental Disorders

Age range

6 year–12 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Institute of Mother and Child

Warsaw, Masovian Voivodeship, 01-211, Poland

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Providing informed consent for participation in the study by the child's legal representative - parent or legal guardian.
  • Diagnosis of autism spectrum disorder according to DSM-5 or ICD-11 criteria.
  • Ability to swallow an empty test capsule identical in shape and size to the investigational product
  • Abnormal stool consistency observed by parents for at least 2 months prior to study inclusion.

Patients with an average stool consistency greater than 5 on the Bristol Stool Form Scale (BSFS) during the baseline period will be classified as having diarrhea.

Patients with an average stool consistency less than 3 on the Bristol Stool Form Scale during the baseline period will be classified as having constipation.

Exclusion criteria

  • Presence of a gastrointestinal disease such as celiac disease, food allergy, inflammatory bowel disease, pancreatitis, chronic liver disease, eosinophilic esophagitis, peptic ulcer disease of the stomach or duodenum, Hirschsprung's disease.
  • Primary or secondary immunodeficiency, including absolute neutrophil count in peripheral blood <1500 measured within 28 days prior to planned FMT.
  • History of surgery involving disruption of intestinal continuity within 3 months prior to study inclusion.
  • Lactose or fructose intolerance. Patients with lactose intolerance who follow an elimination diet and still experience symptoms may be included in the study.
  • Malnutrition defined as Body Mass Index (BMI) below the 3rd percentile based on Polish growth charts from 2010.
  • Overweight or obesity defined as BMI above the 85th percentile based on Polish growth charts from 2010.
  • Active infection requiring antibiotic therapy.
  • Expected use of antibiotics during participation in the study.
  • Use of probiotics during participation in the study.
  • Inability to undergo bowel cleansing therapy (Dicopeg Endo).
  • Inability to swallow an empty test capsule.
  • Lack of consent from the child's legal representative - parent or legal guardian - for participation in the study.

Treatment and study plan

MBiotix® HBI Caps

Other

MBiotix HBI Caps (Human Biome Institute, Poland) are enteric-coated capsules containing a concentrated suspension of gut microbiota obtained by centrifugation of a solution prepared from 60 g of donor stool suspended in 200 ml of 0.9% NaCl and glycerol. Each capsule set contains approximately 10¹³ viable bacterial cells.

Dosing depends on body weight:

Children weighing **>35 kg** will receive 60 g at visit 1 and 30 g at visits 2 (after 4 weeks) and 3 (after 8 weeks).

Children weighing **<35 kg** will receive 30 g at visit 1 and 15 g at visits 2 (after 4 weeks) and 3 (after 8 weeks).

Placebo

Other

Placebo

Primary outcomes

  1. Number of patients who showed an improvement in stool consistency by at least 1 point on the Bristol Stool Scale compared to the baseline period.

    Time frame: 4,8,9,12,26,20 weeks

    The average stool consistency will be calculated from the one-week baseline period and from weekly observation periods during the study.

Secondary outcomes

  1. Bowel movements

    Time frame: 4,8,9,12,16,20 weeks

    Change in the number of bowel movements compared to the baseline period.

  2. Abdominal pain episodes

    Time frame: 4,8,9,12,16,20 weeks

    Change in the number of abdominal pain episodes compared to the baseline period.

  3. Days with abdominal pain

    Time frame: 4,8,9,12,16,20 weeks

    Change in the number of days with abdominal pain compared to the baseline period. Endpoints assessing abdominal pain will be evaluated only in children who are able to communicate their symptoms.

  4. Excessive gas

    Time frame: 4,8,9,12,16,20 weeks

    Change in the number of days with excessive gas according to parent's assessment.

  5. Regurgitation

    Time frame: 4,8,9,12,16,20 weeks

    Change in the number of days with regurgitation compared to the baseline period.

  6. Vomiting

    Time frame: 4,8,9,12,16,20 weeks

    Change in the number of days with vomiting compared to the baseline period.

  7. Child absence

    Time frame: 4,8,9,12,16,20 weeks

    Change in the number of days absent from kindergarten or school due to symptoms.

  8. Parent's work absence

    Time frame: 4,8,9,12,16,20 weeks

    Change in the number of days of parental or caregiver work absence due to symptoms

  9. Adverse events

    Time frame: 0,4,8,9,12,16,20 weeks

    Adverse events reported by children and parents, recorded in the symptom diary and reported to the physician.

  10. SRS-2

    Time frame: 9,20 weeks

    Change in the score of the psychological test Social Responsiveness Scale-2 (SRS-2) compared to baseline.

  11. ASRS

    Time frame: 9,20 weeks

    Change in the score of the psychological test Autism Spectrum Rating Scales (ASRS) compared to baseline

  12. ADOS-2

    Time frame: 9,20 weeks

    Change in the score of the psychological test Autism Diagnostic Observation Schedule-2 (ADOS-2) compared to baseline.

  13. CBCL

    Time frame: 9,20 weeks

    Change in the score of the psychological test Child Behavior Checklist (CBCL) compared to baseline.

  14. ABAS-3

    Time frame: 9,20 weeks

    Change in the score of the psychological test Adaptive Behavior Assessment System-3 (ABAS-3) compared to baseline.

  15. QoLA

    Time frame: 9,20 weeks

    Change in parental quality of life assessed using the Quality of Life in Autism Questionnaire (QoLA) compared to baseline.

Study contacts

Contact information is provided by the study sponsor or research team.

Anna Liber

CONTACT

[email protected]

+48 223277234

Sponsors and collaborators

Lead sponsor

Institute of Mother and Child, Warsaw, Poland

Other

Collaborators

  • Human Biome Institute S.A.

Registry information

Official study title

Fecal Microbiota Transplantation in Children With Autism Spectrum Disorder and Gastrointestinal Symptoms: A Pilot Study

Acronym: FMT-ASD-GI

Important dates

Study start
2026
Primary completion
2026
Study completion
2027
First posted
Jan 27, 2026
Registry last updated
Jan 27, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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