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.