Above: Homogenized fecal matter for transplantation (Wikimedia Commons/Cjc2nd)

You have probably heard of heart, lung, and kidney transplants. These medical procedures have saved thousands of lives over the past few decades. Now, a new kind of transplant has been developed to cure life-threatening infections. But in this case, it’s not an organ being moved from one person to another. It’s poo!

Fecal transplants might sound gross. However, they have become a popular option for treating infections caused by Clostridium difficile. This bacterium can infect the human intestine. Here, it causes symptoms that include diarrhea, fever, and abdominal pain. Not all C. difficile infections are severe. Some people carry the bacteria in their colons and don’t show any symptoms at all. However, 8% of infections are fatal.

Did you know? Clostridium difficile is the most common cause of infectious diarrhea in Canadian hospitals. If visiting a hospital or long-term care facility, make sure to wash your hands or use hand sanitizer to help prevent the spread of infection.

Antibiotics can help...but not always

People suffering from C. difficile infections are usually treated with antibiotics to kill the bacteria. However, C. difficile can produce spores. This allows the bacteria to go dormant until the antibiotic treatment is over. After the treatment, it can start growing again and cause a new infection.

People who have previously taken antibiotics are at greatest risk for developing a C. difficile infection. This is because antibiotics kill off many of the trillions of “good” bacteria that are normally found in the human gut. In fact, the normal bacteria in your intestine protect you from many infections. This is why upset stomach and diarrhea are common side effects of taking antibiotics.

Once these “good” bacteria are gone, it’s easier for the harmful bacteria (like C. difficile) to move in. Think of C. difficile as a weed that grows much more easily on a sparse, patchy lawn than in a lush, well-tended garden.

When antibiotics don’t help

For patients with C. difficile infections that cannot be cured using antibiotics, fecal transplants may be the answer. Doctors take a stool sample that contains a stable community of bacteria from a healthy person’s intestine. Then, they dilute the stool sample in water.

Doctors then give the diluted stool sample to the patient in one of two ways:

  • Doctors may use a nasogastric tube to pass the sample through the patient’s nose down their throat and stomach and into the intestine.
  • Doctors may use a colonoscopy. Here, a tube is passed through the anus into the large intestine. Studies have shown that this simple procedure cures more than 90% of recurring C. difficile infections.

Did you know? Bacteria make up about 55% of the dry weight (excluding water) of human stool. The average person produces about 100 grams of stool per day, containing more than a thousand times more bacteria than there are people on earth!

Risks of fecal transplants

So why not treat every C. difficile infection with a fecal transplant? Like all medical procedures, fecal transplants can have risks. One major risk is that the stool donor might have an infectious disease. For example, if the donor has a virus or a parasite, it could be transferred to the patient. To avoid this, donors are intensively screened. This screening process involves a pre-screening interview. This is similar to a blood donation questionnaire in which the potential donor’s medical history is examined. Potential donors who pass the pre-screening interview next undergo a series of stool and blood tests to ensure they are not carrying any infectious microorganisms. 

Also, all humans have unique bacterial communities in their guts. Bacterial communities are made up of different species of bacteria living in the same areas of the gut. These bacterial communities can change from day to day as a result of diet and other environmental factors. So if two stool samples were taken from the same donor on different days, the types and numbers of bacteria might be different. This means that the fecal transplant treatment might work well on one day, and not another.

To get around these problems, scientists are working on other options to fecal transplants. For example, scientists are growing bacterial communities in the lab rather than taking them from donors. This way, it’s possible to know exactly which bacteria are present, and scientists can be sure that the mixture is free of harmful microbes.

Researchers at the University of Guelph developed a mixture of 33 different types of lab-grown bacteria called RePOOPulate. In 2013 the mixture was tested on two patients with recurring C. difficile, both were cured of their illness. While this makes RePOOPulate a promising treatment more study and testing will be required before this treatment is commonly available. ,

For now, fecal transplants are considered an experimental treatment for C. difficile infection. But the high rate of success means that they are likely to become more common. In fact, studies are underway to see whether fecal transplants might be effective in treating other intestinal diseases such as inflammatory bowel disease (IBD). Modern medicine is finally becoming aware of the power of poo!

This article was updated by Let's Talk Science staff on 2016-10-14 to improve readability by reducing the reading grade level.

Learn more!

Online resources

B.C. wants Health Canada to allow fecal transplant therapy (2014)

Wendy Stueck, Globe and Mail

Report on research into fecal transplants and lab-grown alternatives.

Stool substitute transplant therapy for the eradication of Clostridium difficile infection: ‘RePOOPulating’ the gut (2013)

E. O. Petrof et al., Microbiome 1(3)

Article discussing the development and testing of lab-grown alternatives to fecal transplants.

RePOOPulate: Fecal Transplants without the GROSS POO! (2013)

Scott Unger, Experimental Podcasts, episode 50

Interview with University of Guelph researcher Emma Allen-Vercoe on lab-grown alternatives to fecal transplants.

A miracle cure, not for the squeamish (2013)

Kate Lunau, Macleans

Report on the potential of fecal transplants for treating conditions such as heart disease, Chohn’s disease, and autism.

Swapping Germs: Should Fecal Transplants Become Routine for Debilitating Diarrhea? (2011)

Maryn McKenna, Scientific American

Report on the potential of fecal transplants for treating diarrhea and barriers to its acceptance.

The microbial contribution to human faecal mass (1980)

A. M. Stephen & J. H. Cummings, Journal of Medical Microbiology 13, 45-56

Article calculating the amount of bacteria in human faeces.

Other resources

M. Austin, M. Mellow & W. M. Tierney. (2014). Fecal Microbiota Transplantation in the Treatment of Clostridium difficile Infections. American Journal of Medicine 127(6),479-483.

Article discussing the success and potential of fecal transplants for treating C. difficile. An abstract is available on the journal’s website but a subscription is required to view the full text.

O. E. Petrof & A. Khoruts. (2014). From Stool Transplants to Next-Generation Microbiota Therapeutics. Gastroenterology 146(6), 573-1582.

Article discussing the potential of fecal transplants for treating diseases other than C. difficile. An abstract is available on the journal’s website but a subscription is required to view the full text.

S. R. Eaton and J. E. Mazuski. (2013). Overview of Severe Clostridium difficile Infection. Critical Care Clinics 29(4), 827-839.

Article discussing the treatment and prevention of C. difficile. An abstract is available on the journal’s website but a subscription is required to view the full text.

B. P. Willing, S. L. Russel & B. B. Finlay. (2011). Shifting the balance: antibiotic effects on host-microbiota mutualism. Nature Reviews Microbiology 9, 233-243.

Review article discussing the negative effects of antibiotic treatment on intestinal bacteria and how these effects can be mitigated. An abstract is available on the journal’s website but a subscription is required to view the full text.

C. J. Damman CJ et al. (2012). The Microbiome and Inflammatory Bowel Disease: Is There a Therapeutic Role for Fecal Microbiota Transplantation? American Journal of Gastroenterology 107, 1452-1459.

Article discussing the potential of fecal transplants for treating inflammatory bowel disease. An abstract is available on the journal’s website but a subscription is required to view the full text.

Stefanie Vogt

Born and raised in Edmonton, AB, I completed a Ph.D. in Microbiology & Biotechnology at the University of Alberta in 2013. Currently, I’m a postdoctoral fellow studying microbiology at the University of British Columbia. I think all areas of science are awesome, but I’m particularly interested in understanding how bacteria sense their surroundings and cause infections. Outside of the lab, I enjoy travelling, curling, and learning to play the cello.

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