Reports of faecal transplant recipients taking on certain characteristics of their donors such as depression and obesity highlights the need for a national stool bank with samples sourced from healthy, carefully screened donors, a conference has heard.

Anecdotal evidence from around the world is pointing to the possible bizarre side effect of the increasingly popular treatment, Austin Health infectious diseases physician Associate Professor Patrick Charles told the Royal Australasian College of Physicians’ annual congress on Tuesday.

Faecal Microbiota Transplant (FMT) is now widely accepted in Australia as the most efficacious treatment for recurrent or refractory Clostridium difficile infection, with a reported cure rate of 81 to 94 per cent.

It’s also gaining popularity to treat other conditions including irritable bowel syndrome and ulcerative colitis, however the Gastroenterological Society of Australia does not support such uses outside clinical trial settings.

At the Austin, where it’s been used in a small number of people to treat intractable C. difficile, patients are warned about the possible risk they could develop a characteristic of their donor.

“What has been shown in some cases is there has been some possible association, where the recipient takes on some characteristics of the donor in the form of their weight, so if the donor is overweight or underweight then the recipient can become similar,” Professor Charles told the limbic.

“Also there have been people who have never had depression who had the transplant from someone who had depression and then ended up becoming depressed”.

He said it was possible that particular combinations of bacteria that affect metabolism may be behind changes to mood, but it was too early to draw conclusions.

“It’s too soon to say there’s solid evidence right now, but it’s certainly something that warrants a lot more investigation and research.”

“We still have a long way to go before we really understand it,” he said.

According to Professor Charles the reports, while anecdotal, pointed to the need for a stool bank with samples sourced from healthy, carefully screened donors.

Related story: GESA calls for frozen stool banks

“Even further into the future what we’ll hopefully have is a pharmaceutically produced artificial stool that has the right mix of these various bacteria,” he said.

In the meantime, Professor Charles makes a point of explaining the potential risks associated with the procedure to his patients.

“A lot of the time, in my experience, the patients are so desperate to get rid of the diarrhoea they say ‘I’ll take the risk’,” he said.

“I think it’s just a matter of being open and honest with the patient as to the potential that’s maybe there.

“It’s probably a small risk, but it’s a risk.”