The gut microbiota is the collection of microorganisms living inside our body. We have tens of trillions of microbes living in our guts, totaling more than 3 million genes.
Our gut microbiomes are crucial for our immunity and overall health. They act as a barrier against other harmful microorganisms, and they help with digestion and the production of some vitamins.
Previous research has suggested that the composition of the microbiome influences the development of certain diseases, including inflammatory bowel disease, irritable bowel syndrome, deadly bacteria infections, enterocolitis, and obesity.
Some studies have even linked the composition and diversity of the gut microbiome with autism spectrum disorders (ASD).
ASD is a developmental disability affecting approximately 1 in 68 children in the United States, according to the Centers for Disease Control and Prevention (CDC).
Improving the gut microbiome in ASD patients
The research, consisting of an open-label clinical trial, was a collaborative effort between Arizona State University (ASU), Ohio State University, and the University of Minnesota. The team was led by James Adams, ASU President's Professor of materials science and engineering, along with two other ASU professors: Rosa Krajmalnik-Brown and Dae-Wook Kang.
The team gathered 18 study participants with ASD, aged between 7 and 16, who underwent a 10-week treatment consisting of antibiotics, bowel cleansing, and an extended fecal microbiota transplant.
More specifically, the scientists administered an antibiotic treatment for 2 weeks, a bowel cleanse, and a fecal microbiota transplant that used a high dose in the first couple of weeks, and then lower, daily doses for the remaining 8 weeks.
Fecal microbial transplantation is a form of treatment shown to be effective for treating Clostridium difficile infections. During the procedure, fecal matter is collected from the stool of a carefully selected, healthy donor and transplanted into the colon of a patient using a variety of methods, including orally-administered capsules, colonoscopy, or endoscopy.
For this trial, researchers used a donor microbiome that contained 1,000 different species of gut bacteria, and implemented a treatment regimen previously shown to be efficacious in treating C. difficile infection.
The trial involved 14 days of treatment with vancomycin, which were followed by a 12-24 hour fasting period during which participants had a bowel cleansing. Then, the gut microbiota was repopulated by administering a high dose of standardized human gut microbiota (SHGM) orally or rectally. Finally, the patients received daily, lower doses of the SHGM, together with a stomach acid suppressant for 7-8 weeks.
Participants were then clinically followed for another 8 weeks after the treatment ended, in order to examine whether the effects of the treatment were temporary or long-lasting.
The treatment had 'promising,' long-lasting effects
The results were deemed "compelling" and "promising" by the researchers.
Specifically, the treatment showed an 80 percent reduction of gastrointestinal symptoms previously associated with ASD, as well as significant improvements in behavioral ASD symptoms - such as sleep habits and social skills.
Constipation, diarrhea, indigestion, and abdominal pain all declined during the treatment, as well as 8 weeks after the treatment ended. Similarly, behavioral improvements also persisted during the 8-week follow-up period.
Overall, as a result of the microbiota transplant, bacterial diversity improved, and so did the presence of Bifidobacterium, Prevotella, and Desulfovibrio.
"We saw a big increase in microbe diversity and a big increase in certain bacteria, especially Prevotella, which we previously found was low in children with autism spectrum disorders," explains study co-leader Prof. Dae-Wook Kang.
"That is compelling, because not only did we provide good microbes, but the microbes we provided changed the gut environment in a way that helped the host recruit beneficial microbes and allowed them to stay around," adds study co-leader Prof. Krajmalnik-Brown.
The authors explain that although the results are very promising, further larger-scale trials are needed.
"The results are very compelling. We completed a phase I trial demonstrating safety and efficacy, but recommending such treatment and bringing it to market requires phase II and phase III trials. We look forward to continuing research on this treatment method with a larger, placebo-controlled trial in the future."
Prof. James Adams
The researchers also caution parents and children against trying to simulate and apply the treatment themselves.
"Although we see promise in this treatment, it is important that parents and children consult their physicians," says Prof. Krajmalnik-Brown. "Improper techniques can result in severe gastrointestinal infection."
Microbiota Transfer Therapy alters gut ecosystem and improves gastrointestinal and autism symptoms: an open-label study, Dae-Wook Kang et al., Microbiome, doi:10.1186/s40168-016-0225-7, published online 23 January 2017.
ASU news release, accessed 23 January 2017 via EurekAlert.
Approaches to studying and manipulating the enteric microbiome to improve autism symptoms, Richard E. Frye et al., Microbial Ecology, doi:10.3402/mehd.v26.26878, published online 7 May 2015.
CDC ASD data and statistics, accessed 23 January 2017.
Gut bacteria in health and disease, Eamonn M. M. Quigley, Gastroenterology and Hepatology, published online September 2013.
Gut Microbiota for Health, Gut microbiota info, accessed 23 January 2017.
Open Biome, What is Fecal Microbiota Transplantation?, accessed 23 January 2017.