The blogosphere has been buzzing lately about the idea of “fecal transplants,” probably because this treatment (first studied in the 80’s) was recently mentioned on Grey’s Anatomy. Proponents of the therapy (which involves the introduction of donor stool into a patient via enema or naso-gastric tube) say that it can rejuvenate intestinal flora and cure c. diff colitis, and various inflammatory bowel disorders. I had my doubts about these claims and decided to interview gastroenterologist Dr. Brian Fennerty to get to the bottom (sorry abou the bad pun) of this issue.
Dr. Fennerty is a Professor of Medicine in the Division of Gastroenterology at Oregon Health & Science University in Portland, Oregon, where he also serves as Section Chief of Gastroenterology.
Listen to the podcast here:
Dr. Val: What exactly is a “fecal transplant?”
Dr. Fennerty: First, by way of background, you need to understand that the GI tract is populated with thousands of varieties of “good” bacteria that are essential for our health. If we didn’t have bacteria in our colon and small intestine, we would die. Fecal transplantation is the repopulation of a person’s gut bacteria (flora) with fecal matter from somebody else. Some argue that this helps to treat certain diseases.
Dr. Val: How is this procedure performed?
Dr. Fennerty: As it was originally described, fecal transplantation involved removing the undigested food particles from the stool sample of a “healthy” person, and then spinning it so that a pellet (of hundreds of thousands of species and quasi-species of bacteria) remains. The pellet is then introduced to the patient through a nasogastric tube into the small intestine, or the pellet can be resuspended in liquid and introduced into the rectum via an enema. The idea is that the bacteria will colonize the patient’s colon and squeeze out the bad bacteria that are in there.
Dr. Val: What are fecal transplants purported to do?
Dr. Fennerty: The theory is that some diseases are caused by an imbalance of good and bad bacteria in the human gut. The imbalance could be caused by antibiotic use or exposure to bad bacteria like clostridium difficile (c. diff). The argument is that introducing fecal bacteria from another person can promote colonization of the colon and intestines so that the gut ecosystem is shifted away from bad bacterial colonies and towards good ones.
Dr. Val: What is the current evidence for fecal transplantation?
Dr. Fennerty: There have been a few observations that patients with c. diff colitis have improved after fecal transplantations. I use the term “observations” because the only way that we can be certain that the treatment is benefitting the patient (and it’s not just time that’s benefitting the patient) is to do a controlled trial. That means that half of the patients would receive a fecal transplant and the other half would receive either no treatment or a placebo. Then we’d have to see if the ultimate outcomes of those two groups is different. The fecal transplant literature to date is purely observational. So we’d like to think that patients get better with fecal transplants but we don’t know that for sure.
Dr. Val: Why wouldn’t people just eat yogurt (or good lactobacillus bacteria) instead of replacing all their flora with someone else’s mix of good and bad?
Dr. Fennerty: Probiotics use a few strains of bacteria that we know are safe and healthy for the gut. The fact is that we don’t know which strains of good bacteria are the best at repopulating the gut and protecting against disease. Most of the information we have on probiotics is observational – so we really don’t know how much good they do.
Fecal transplant proponents argue that stool contains all the possible choices, so it has a better chance of treating disease. Probiotic proponents argue that fecal transplants are uneccessarily risky because they convey all sorts of negative pathogens along with the good ones. They argue that it’s best to stick with one form of good bacteria (such as lactobacillus) since it’s known to be safe. There is a real rift forming between these two camps, with lots of interesting theories but no real evidence for any of the claims.
Dr. Val: So what are the risks of fecal transplantation?
Dr. Fennerty: Our colons are not just full of bacteria, but they can also be populated with viruses, fungi, and protozoa. Fecal transplants can transmit HIV, mad cow (prion) disease, e. coli, shigella and other dysentery-causing infectious agents. So the medical community is very concerned about the potential for fecal transplants to transmit dangerous and even deadly illnesses. We can’t control all these pathogens with laboratory tests – some (especially prions) can avoid detection. It’s impossible to declare a stool sample safe with our current technology. In addition, we have no substantial evidence at this point that fecal transplants actually improve c. diff infections or inflammatory bowel disease.
Dr. Val: What should Americans know about fecal transplants?
Dr. Fennerty: They should know that this is not a new treatment, it’s been around for decades. Even though intuitively the treatment makes sense, until we know how to do it safely (and we have good evidence that it’s worthwhile in the first place) we have to temper our enthusiasm. That’s a very difficult thing to tell someone who has a disease. But fecal transplants are simply not ready for prime time.