TABLE 5.

Intervention studies of FMT and MTT.

Authors	Study design	Treatment	Effect on gut microbiota	Effect on behavioral symptoms	Effect on GI symptoms
Linda et al. (2016)	Cohort study of 9 ASD patients (2, 3, 5, 5, 6, 8, 8, 11, and 21 years of age)	FMT	Bacteroides, Barnesiella, Parabacteroides, Sutterella, Parasutterella, Clostridiales, and Erysipelotrichales were most altered	Improved behavioral symptoms significantly of ASD children, with the exception of 21 years old subjects	–
Kang et al. (2017)	Cohort study of 18 ASD patients aged 7–16 years	MTT	Increased the diversity of bacteria in their gut, with the increased abundance of Bifidobacterium, Prevotella, and Desulfovibrio. And both of these changes persisted after treatment stopped (for 8 weeks)	Improved behavioral symptoms significantly of ASD patients (for 8 weeks)	GI symptoms improved (for 8 weeks)
Zhao et al. (2019)	Randomized, double-blind, controlled study of 48 ASD patients	FMT	Decreased the abundance of Bacteroides fragilis, and the gut microbiota of ASD patients gradually transferred to a healthy state. Changes of CARS were negatively correlated with Coprococcus	Decreased the CARS scores of the FMT group by a statistically significant 10.8% compared with a 0.8% decrease in the control group after the first FMT (F1), and still decreased slightly after the second FMT (F2)	Notable differences were also shown on GSI scores (P < 0.05) at F1 time point. 7 (29.2%) patients in FMT group reported adverse events such as fever, allergy and nausea, but all of them were mild, transient

FMT, Fecal microbiota transplant; MTT, Microbiota Transfer Therapy; CARS, Childhood Autism Rating Scale; GSI, Gastrointestinal Severity Index; GI, gastrointestinal.