Investigating stagnant clinical outcomes after fecal microbiome transplant in autism spectrum disorder.

The impact of fecal microbiome transplant (FMT) on autism spectrum disorder (ASD) symptom recovery has been previously investigated with widely varying success rates. The goal of this study is to determine criteria for reliable assessment of FMT recovery and investigate possible explanations for stagnant ASD FMT recovery outcomes. The results from this study show evidence of decreased bacterial diversity in a subset of patients with poor clinical outcomes, even after FMT. These patients display differential profiles for Akkermansia, a gut microbe associated with mucin degradation, as well as differential levels of metabolites including tryptophan derivatives and pyroxidal, a vagus nerve afferant polarizer. These results are expected to help explain gut-brain axis mechanisms associated with FMT success in ASD.