How Fecal Microbiota Transplants Work

There are transplants of hearts and lungs, even hands and faces; kidneys are donated, so are lobes of livers.

It sounds pretty gross, but there are also stool transplants.

A stool transplant doesn't involve the surgery or immune system suppression like organ transplants require. It is though life-saving for some.

It's really not as crazy as it might sound. We all have bacteria in us, all the time. In fact, we probably have 100 trillion bacteria in us at any time. It's all part of our microbiome that includes bacteria on our skin, in our gut, and many other parts of our bodies. Bacteria outnumber human cells about 10:1. We "only" have 10 trillion human cells.

Such transplants are called Fecal Microbiota Transplants (FMT) or Stool transplants. These transplants can treat disorders that occur when the bacteria in our gut are not what they should be. Usually there are many, many different types of bacteria in our guts. There is a complex ecosystem in balance within our guts. Sometimes these ecosystems can be washed away by antibiotics and can be overrun by just one type of bacteria such as C Diff (Clostridium Difficile). Stool transplants have primarily been used for recurrent C Diff infections.

Medical tests Nurse in lab

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What Is Clostridium Difficile?

Clostridium difficile (C. difficile) is a bacteria that can overgrow in the intestines when patients are given antibiotics, particularly when they are in healthcare facilities where others are infected and when they are themselves ill. It can lead to severe diarrhea. It caused about 500,000 infections in 2011. It often causes recurrences—over 80,000 in the US who had the infection had it at least twice. Of those infected, almost 30,000 died within 1 month of their diagnosis with C Diff.

C Diff can be treated with antibiotics, but recurrences are common and some cases do not respond to antibiotics. C Diff overgrowth occurs when normal bacteria in the gut may have been wiped out by antibiotics and the normal flora needs to return to avoid C Diff recurring and recurring. Otherwise, patients can suffer and in some cases die from the effects of continuous diarrhea.

Transplants for Other Diseases?

There have been other intestinal overgrowth diseases (including MRSA) for which these transplants have been used. As we learn more about the microbiome and its role in human health, there has been hope for applications in inflammatory bowel disease (including Crohn's disease), irritable bowel syndrome, liver disease (complicated by high levels of ammonia), metabolic syndromes, other intestinal infections, and many other diseases. However, there is much to learn before such transplants can be used in many of these contexts. There are studies being conducted to better understand how this approach may help in diseases like Crohn's, ulcerative colitis, and liver disease.

As we begin to understand the complexities of the microbiome, we may understand further roles beyond C Diff treatment.

Whose Stool Is Used?

Usually, a close household or family member, such as a spouse, has been the stool donor. There are however stool banks that have developed to provide stool as well, though there was initially some regulatory issues regarding the use of stool banks.

How Donors Are Selected

Donors are given blood tests for HIV, Hepatitis A, B, C, as well as syphilis. Their stool is examined for parasites and parasite eggs and additionally tested for Helicobacter pylori, Giardia, Cryptosporidium, as well as of course C difficile.

There have been cases of unwanted infections, such as norovirus diarrheal infections, which have spread through transplantation.

The point, however, is for bacteria to be transplanted, so all transplants do result in the transfer of bacteria.

How Transplants Are Given

There are a variety of ways the stool may be given. Except in the case of frozen stool from stool banks, it is usually prepared 'freshly' in hours. It is generally mixed with a water solution, blended, and given within 6 hours either through a nasogastric tube, an enema, or through a colonoscopy.

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