Kang · Microbiome 2017 · open-label single-arm clinical trial · n=18

Microbiota Transfer Therapy alters gut ecosystem and improves gastrointestinal and autism symptoms: an open-label study.

Cited 1400 times in the scientific literature.

Level 4 - case-series / case-control

Uncontrolled open-label interventional study (case series)

PubMed 28122648 · doi:10.1186/s40168-016-0225-7 · record verified 2026-08-28

What was done

An open-label trial evaluated Microbiota Transfer Therapy (MTT) in 18 children diagnosed with autism spectrum disorder (ASD) and gastrointestinal (GI) symptoms. The protocol comprised a 2-week course of oral antibiotics, a bowel cleanse, and an extended fecal microbiota transplant protocol featuring a high initial dose followed by daily lower maintenance doses for 7–8 weeks. Outcomes evaluated included changes on the Gastrointestinal Symptom Rating Scale (GSRS), standardized clinical behavioral assessments, and deep sequencing analysis of bacterial and phage gut communities at the end of treatment and 8 weeks post-treatment.

What was found

The Gastrointestinal Symptom Rating Scale showed an approximately 80% reduction in GI symptoms at the end of treatment, with significant improvements across constipation, diarrhea, indigestion, and abdominal pain that persisted 8 weeks post-treatment. Behavioral ASD symptoms also improved significantly and remained improved at the 8-week follow-up. Sequencing demonstrated partial donor microbiota engraftment, increased overall bacterial diversity, and persistent increases in specific taxa, including Bifidobacterium, Prevotella, and Desulfovibrio.

Why it matters

The study provides proof-of-concept human data suggesting that extended microbiota transfer can modify gut microbial composition and is correlated with improvements in both gut and behavioral symptoms in ASD.

Limits

The study was small (n = 18), open-label, and lacked a control or placebo group, introducing substantial risk of placebo effect, observer bias, and regression to the mean. The combination protocol (antibiotics, bowel cleanse, and extended FMT) makes it impossible to isolate the specific contribution of the transplant itself. Follow-up was limited to 8 weeks after treatment cessation.

Cited by