[music playing] ED YONG: Clostridium difficile, or c-diff-- a nasty, weedy bacterium that can cause chronic, painful diarrhea.

In the US every year, hundreds of thousands of people are infected by c-diff.

And tens of thousands die from it.

And often, people get it after taking antibiotics.

But scientists have finally found a material that can cure c-diff infections.

And that material is poop.

[bubbly liquid sound] Uh, we call it mostly poo.

ED YONG: This is Mark Smith, the microbiologist and founder of a nonprofit called Open Biome, based in Massachusetts.

He is one of many scientists who are trying to fight c-diff infections through a rather unorthodox treatment called-- Fecal microbiotic transplantation.

Or FMT.

The M can stand for microbiome or microbe.

The T sometimes stands for therapy or treatment.

But the F-- the F always stands for feces.

MARK SMITH: We're taking stool, we're processing it, and extracting the bacterial component.

So you're taking poop from a healthy person, and you're putting it into a sick person.

Who came up with this idea?

Yeah, this has been used as a medical therapy, you know, dating back to, sort of, ancient Chinese medicine.

This idea of human feces that would be delivered in a yellow soup, to treat digestive diseases.

ED: In the 1950s, reports started coming in about the successful use of fecal transplants, to treat a variety of different conditions.

And then in the late 2000s, many doctors independently started using FMT to treat seemingly incurable c-diff infections.

Clinical trials began, and hundreds of people were successfully treated.

So Mark, how does a dose of poop cure c-diff?

What's going on in there?

So, you know, when I think about the microbiome, I think about it as this chaotic, little city within us.

So you have some bacteria that are blooming, others that are dying, sort of this, you know, mad, mini civilization that's going on.

And what happens to the civilization when you take a long, powerful course of antibiotics?

Imagine there were like, bad guys on the loose, and we said, ah, you know what?

We've just got a nuke them and get rid of everybody that's living here.

That's kind of the approach that we're taking with a lot of these bacterial infections, where rather than just going after the bad guys, we're going after everybody.

And, you know, then, all of a sudden, you've got this sort of post-apocalyptic nightmare afterwards, where you've killed all the-- not just the bad bacteria that were causing your infection, but also a lot of the good guys.

And in this environment, you know, you're-- a lot of bad guys emerge and sort of loot this city that's left over.

So in a healthy person, this rich, thriving community of bacteria keeps c-diff in check.

Yeah, and when those bacteria are disrupted or eliminated by antibiotic exposure, that opens up this niche space for c-diff to go in and take advantage, multiply its population size.

ED: And so when you give people a dose of poo, you're reintroducing all of those missing bacteria.

MARK: You know, it's comprised of thousands of different strains of bacteria, and they're all regulating each other and changing their behavior in real time.

It's like an ecosystem transplant.

Exactly.

And Mark, fecal transplants are really effective, right?

They're the best bet for some c-diff patients.

Fecal transplantation works well.

It works about 85% to 90% of the time, in these patients that otherwise fail to respond to antibiotics.

These are the sickest of the sick patients.

You know, chronic diarrhea, they're, I mean, you know-- 10, 20 bowel movements every day, maybe for months.

They will-- usually within a couple of days-- be back to normal.

And it's amazing, when you talk to these patients.

ED: Open Biome is one of a growing number of nonprofit stool banks that collect, process, and distribute stool for fecal transplants.

Most of it comes from local college students, who make 40 bucks per deposit.

NURSE: Do you have your donation card?

ED: The screening process is rigorous.

The chance of passing on a disease must be minimized, so you can't be on any medication or have traveled overseas, where you could have picked up a dangerous pathogen.

Less than 5% of people pass and become donors.

In this lab, they turn the stool into medicine.

It starts off as, you know, the poo that we all know and love.

Some of us maybe love more than others.

And then we add a cyro-protectant, to protect it from the freezing process, and an osmo-protectant, to protect it from the cells bursting from being exposed to water.

And that sort of dilutes it up and turns it into more of a liquid slurry.

And then it gets pushed through a filter to remove the fibrous material.

So then it's a really thin liquid, still a thin, brown liquid, and ends up looking a lot like chocolate milk.

So you think about Charlie and the Chocolate Factory, the big chocolate waterfall, we've got a much thinner one of those that is our, kind of, core process.

ED YONG: The fecal matter is then placed in plastic containers, frozen, and sent out.

Hospitals then deliver it into patients, either by colonoscopy, or by a tube that goes down their nose, into their gut-- or, most simply, buy a pill, a pill filled with poop.

Fecal transplants work really well for treating c-diff, but what about other conditions?

We're looking at ulcerative colitis, we're looking at Crohn's disease, we're looking at Pouchitis.

We're looking at irritable bowel syndrome.

We have work in obesity.

ED: But in clinical trials of other conditions, fecal transplants have not been as effective.

Still, scientists like Mark are hopeful that with more research, they will become a new way of treating disease.

MARK: Yeah, yeah, exactly.

ED: By harnessing the power of poop.

MARK: The most gratifying part of my day is to see a big pile of boxes, that are filled with dry ice and poo, and going out to hospitals and clinics all over the country.

ED: Fecal transplants are bizarre.

They are revolting.

They are implausible.

And yet, they work, and they reveal the power of the microbiome.

Perhaps, it's time for us all to start giving a [bleep]..