A substitute stool mix helped to treat two people with C. difficile infections that failed to respond to antibiotics, an early stage Canadian study suggests.

The infections can be caused by antibiotics that kill off healthy bacteria in the gut allowing C. difficile to flourish. Patients can develop symptoms like fever, diarrhea, abdominal cramps, and inflamed colons.

Fecal transplants are used to treat debilitating, repeat infections from C. difficile bacteria. But the ick factor of receiving someone else's stool in your colon and concerns about transmitting infection have limited use of the practice.

To overcome those barriers, researchers invented a stool substitute mixture containing different species of bacteria from a healthy woman. The bacteria were grown in a robotic gut called RePOOPulate, a collection of tubes and devices designed to mimic the human intestines.

"This pilot study shows that a … stool substitute may be an effective and feasible alternative to the use of defecated donor fecal matter [stool transplant] in the treatment of recurrent C. difficile infection," University of Guelph microbiologist Emma Allen-Vercoe and her-co authors from Kingston, London and Guelph concluded in Tuesday's issue of the journal Microbiome.

Fecal transplants are used to treat debilitating, repeat infections from C. difficile bacteria. (Lois S. Wiggs/U.S. Centers for Disease Control and Prevention)

The researchers said the advantages of the substitute approach included:

• Knowing and controlling the exact composition of the bacteria given, including their resistance to antibiotics, if future treatment is needed.
• The cultures are more stable than fresh stool.
• Lack of viruses and other disease-causing microbes to improve patient safety.

The first patient was a 74-year-old woman who first developed C. difficile after elective knee surgery. The patient originally had a diverse mix of microbes in her gut, but she had six episodes of infection over 18 months that required hospitalization, the researchers said.

After the woman was treated with the stool substitute, her normal bowel pattern returned and scientists said they detected no C. difficile after 20 days. She stayed free of symptoms up to her last evaluation 24 weeks after the colonoscopy treatment to deliver the substitute.

The second patient was a 70-year-old woman who had repeat skin and soft tissue infections that were occasionally treated with broad-spectrum antibiotics for up to four weeks, the researchers said.

Given the differences between the patients, the study's authors acknowledged it's difficult to draw conclusions for a broader population until more patients are tested.

RePOOPulate hasn't been approved by Health Canada, which is allowing it to be used in the experiment.

Dr. Susan Poutanen, an infectious disease specialist at Mount Sinai Hospital in Toronto, is working on a larger clinical trial of standard fecal transplants.

Poutanen called the synthetic stool findings exciting but noted it isn't yet clear what the best mix of microbes is or what's the best way of delivering the treatment.

The study was funded by the Southeastern Ontario Academic Medical Association, Physicians' Services Incorporated Foundation and University of Western Ontario Academic Development Fund.

With files from CBC's Pauline Dakin