Scientists have found that the bacteria in the gut of autistic children is different from that of non-autistic children.

Researchers from the Mailman School of Public Health at Columbia University found that microorganisms residing in the gut of autistic children are different from other children but they are yet to determine whether these gut differences are a cause or an effect of autism, reports the American Society For Microbiology (ASMUSA).

The results, published in the mBio journal, found that a bacteria belonging to the Sutterella group in the gut was found in 12 of 23 tissue samples from autistic children. The same bacteria were not present in the samples of non-autistic children.

According to Jorge Benach, Chairman of the Department of Microbiology at Stony Brook University: “The Sutterella bacteria has been associated with gastrointestinal diseases below the diaphragm, and whether it's a pathogen or not is still not clear. It is not a very well-known bacterium."

Scientists are now hoping to find out why this organism is only present in autistic children.

“The relationship between different microorganisms and the host and the outcomes for disease and development is an exciting issue," says Christine A. Biron, Professor of Medical Science at Brown University.

"This paper is important because it starts to advance the question of how the resident microbes interact with a disorder that is poorly understood," adds professor Biron.

The study used tissue samples from the guts of the children. Scientists believe the results could provide a positive step towards finding a direct link between digestive problems and behavioural traits in autistic children.

“Most work that has been done linking the gut microbiome with autism has been done with stool samples," explains Benach. “But the microorganisms shed in stool don't necessarily represent the microbes that line the intestinal wall. "What may show up in a stool sample may be different from what is directly attached to the tissue.”

Georgina Gomez-de-la-Cuesta, Action Research Leader for The National Autistic Society added to this, telling The Huffington Post:

"People with autism can often experience gut problems, but there is little evidence to suggest a causal relationship between the two conditions. While this research identifies differences in gut bacteria between children with autism and children without the condition, more studies looking at children with a range of symptoms are needed to confirm any connection and understand the biological processes that underlie this.

"Managing gut problems can help improve behaviour for some people with autism by alleviating physical discomfort and stress. However, this should be viewed as a complementary method and is not a treatment for autism in itself."

The full report can be found on the mBio journal website.