From Crap to Cure: The Story of Fecal Transplants
C. difficile had Meg Newman's number; it had struck her 18 different times beginning in 1985. The bacterial infection takes over the gut bringing explosive diarrhea, dehydration, weight loss, and at its worst depletes blood platelets. It causes nearly 30,000 deaths each year in the U.S. alone.
"I was one sick puppy as that point and literally three days after the transplant I was doing pretty well, day four even better."
Meg knew these statistics not just from personal experience but also because she was a doctor at San Francisco General Hospital. Antibiotics had sometimes helped to treat the infection, but it never quite seemed to go away. Now, "It felt like part of my colon was sort of sliding off as I had the bowel movement." On her worst day she counted 33 bowel movements. It was 2005 and she knew she was at the end of her rope.
Medical training had taught Meg to look at the data. So when antibiotics failed, she searched the literature for other options. One was a seemingly off-the-wall treatment called fecal transplants, which essentially gives poop from a healthy person to one who is sick.
Its roots stretch back to "yellow soup" used to treat dysentery in China nearly two thousand years ago, in which ancient Chinese treaters would combine stool with liquid, mash it up, and administer it. The approach also is commonly used in veterinary medicine today. However, there were only about three papers on its use in humans in the medical literature at that time, she recalls. Still, the logic of the intervention appealed to her.
The gut microbiome as a concept and even a word were not widely known fifteen years ago. But the idea that the microbial community in her gut was in disarray, and a transplant of organisms from a healthy gut might help restore a more normal ecology made sense. And besides, the failure of standard medicine left her few options.
Meg spoke with a colleague, gastroenterologist Neil Stollman, about a possible fecal microbial transplant (FMT). Only a handful of doctors in the U.S. had ever done the procedure; Stollman had tried it just once before. After conversation with Newman, he agreed to do it.
They decided on Meg's partner Sherry as the donor. "I try very hard to use intimate sexual partners as the donor," explains Stollman. The reason is to reduce disease risk: "The logic there is pretty straightforward. If you have unprotected sex with this individual, in a monogamous way for a period of time, you have assumed pretty much any infectious risk," like hepatitis, HIV, and syphilis, he says. Other donors would be screened using the same criteria used to screen blood donations, plus screening for parasites that can live in stool but not blood.
The procedure
Martini aficionados fall into two camps, fans of shaken or stirred. In the early days the options for producing of fecal transplants were a blender or hand shaken. Stollman took the hands-on approach, mixing Sherry's fecal donation with saline to create "a milkshake in essence." He filtered it several times through gauze to get out the lumps.
Then he inserted a colonoscope, a long flexible tube, through the anus into Meg's colon. Generally a camera goes through the tube to look for polyps and cancers, while other tools can snip off polyps and retrieve tissue samples. Today he used it to insert the fecal "milkshake" as high up the colon as he could go. Imodium and bed rest were the final pieces. It works about 90 percent of the time today.
Meg went home with fingers crossed. "And within about two weeks things just slowed down; the diarrhea just stopped. I felt better so my appetite was better." The tide had turned, though it would take months to slowly repair the toll taken on her body from disease and antibiotics.
Then in 2011 another serious medical challenge required heavy use of antibiotics and Meg's C. difficile came roaring back; she needed a second FMT. Sherry had a bad sinus infection and had been on antibiotics, so that ruled her out as a donor. Red, Meg's godson, volunteered. He was twenty-one and had little or no exposure to antibiotics, which can harm friendly bacteria living in the gut.
"I was one sick puppy as that point," Meg recalls, "and literally three days after the transplant [from Red] I was doing pretty well, day four even better. It was unbelievable." It illustrated that donors are not the same, and that while an intimate partner may be the safest option, it also may not be the most efficacious donation in terms of providing missing parts of the microbial ecosystem.
Going mainstream
By then, FMTs were starting to come out of the shadows as more than just a medical oddity. One gigantic milestone in changing perceptions was a Dutch study on using the procedure to treat C. difficile that was published in January 2013 in the New England Journal of Medicine. "That was the first trial where people said, look this isn't voodoo. This wasn't made up; it really worked," says Colleen Kelly, another pioneer in using FMTs to treat C. difficile and a researcher at Brown University. A single dose was successful more than 80 percent of the time in resolving disease in patients who had failed multiple regimens of antibiotics.
Charlatans pounced on the growing interest in the microbiome, promoting FMT as a cure for all sorts of ailments for which there was no scientific evidence. The FDA stepped in, announcing it would regulate the procedure as a drug, and essentially banned use of FMTs until it wrote regulations. But the outcry from physicians and patients was so great it was forced to retreat and has allowed continued use in treating C. difficile albeit on an interim regulatory basis that has continued since 2013.
Another major change was the emergence of stool banks, modeled on blood banks. The most widely know is OpenBiome, established in 2012 as a nonprofit by young researchers at Harvard and MIT. It aimed to standardize donation of stool and screening for disease, and package them in frozen form for colonoscopic delivery, or pill form. It greatly simplified the process and more doctors became willing to use FMTs to treat C. difficile. Today, some gastroenterologists specialize in administering the transplants as a feature of their practice.
To be sure, there have been some setbacks, including a transplant between family members where the recipient became obese, likely in part because of bacteria in the material she received. The same thing has occurred in studies in mice. And last year, an elderly man died from a toxic strain of E. coli that was in material provided by a stool bank. That caused the FDA to add that pathogen to the list of those one must screen for in products designed for use as fecal transplants.
Cost remains an issue. OpenBiome charges $1500-$2000 per transplant dose, depending on whether a frozen or pill form of the product is used. And that is likely to go up as the FDA increases the number of diseases that must be screened for, such as the virus that causes COVID-19, which is present in feces and likely can be transmitted through feces. Most insurance companies do not cover FMTs because no product has been formally approved for use by the FDA.
One of the greatest treatment challenges is making the correct diagnosis, says physician Robin Patel, who initially treated patients at the Mayo Clinic in Rochester, Minnesota but now spends most of her time there developing new diagnostics. Many things can cause diarrhea and the simple presence of the organism does not mean that C. difficile is causing it. In addition, many people are colonized with the bug but never develop symptoms of the disease.
Patel used the expensive tool of whole genome sequencing to look in great detail at C. difficile in patients who were treated with antibiotics for the infection and had recurrent diarrhea. "Some of them, as you might predict, were getting their symptoms with the same exact strain [of C. difficile] but others were not, it was a different strain," suggesting that they had been reinfected.
If it is a different strain, you might want to try antibiotics, she says, but if the same strain is present, then you might want to try a different approach such as FMT. Whole genome sequencing is still too slow and expensive to use in regularly treating patients today, but Patel hopes to develop a rapid, cost-effective test to help doctors make those types of decisions.
Biotech companies are trying to develop alternatives to poop as a source for transplant to treat C. difficile. They are picking and choosing different bacteria that they can grow and then combine into a product, to varying degrees of success, but none have yet crossed the finish line of FDA approval.
"I think [the future of FMTs] is going to be targeted, even custom-made."
The FDA would like such a product because it is used to dealing with small molecule drugs that are standardized and produced in batches. Companies are pursing it because, as Kelly says, they are like sharks "smelling money in the water." Approval of such a product might cause the FDA to shut down existing stool banks that now exist in a regulatory limbo, leaving the company with a monopoly of exclusive rights to the treatment.
Back when Meg received her first fecal transplant, the procedure was so obscure that the guidelines for treating C. difficile put out by the American College of Gastroenterology didn't even mention FMT. The procedure crept into the 2013 revision of those guidelines as a treatment of last resort. Guidance under review for release later this year or early next year will ease use further but stop short of making it a first option.
Stollman imagines a future holy grail in treating C. difficile: "You give me a stool specimen and I run it through a scanner that tells me you have too much of this and too little of that. I have a sense of what normal [microbial composition of the gut] should be and add some of this and subtract some of that. Maybe I even give you some antibiotics to get rid of some of the bad guys, give you some probiotics. I think it is going to be targeted, even custom-made."
His complete vision for treating C. difficile won't arrive tomorrow, but given how rapidly FMTs have become part of medicine, it is likely to arrive in pieces and more quickly than one might think.
About five years ago Meg discovered she had an antibody deficiency that contributed to her health problems, including vulnerability to C. difficile. She began supplementation with immunoglobulin and "that has made a huge difference in my health. It is just unbelievable how much better I am." She is grateful that fecal transplants gave her the time to figure that out. She believes "there's every reason to consider it [FMT] as a first-line treatment and do the studies, ASAP."
Two-and-a-half year-old Huckleberry, a blue merle Australian shepherd, pulls hard at her leash; her yelps can be heard by skiers and boarders high above on the chairlift that carries them over the ski patrol hut to the top of the mountain. Huckleberry is an avalanche rescue dog — or avy dog, for short. She lives and works with her owner and handler, a ski patroller at Breckenridge Ski Resort in Colorado. As she watches the trainer play a game of hide-and-seek with six-month-old Lume, a golden retriever and avy dog-in-training, Huckleberry continues to strain on her leash; she loves the game. Hide-and-seek is one of the key training methods for teaching avy dogs the rescue skills they need to find someone caught in an avalanche — skier, snowmobiler, hiker, climber.
Lume’s owner waves a T-shirt in front of the puppy. While another patroller holds him back, Lume’s owner runs away and hides. About a minute later — after a lot of barking — Lume is released and commanded to “search.” He springs free, running around the hut to find his owner who reacts with a great amount of excitement and fanfare. Lume’s scent training will continue for the rest of the ski season (Breckenridge plans operating through May or as long as weather permits) and through the off-season. “We make this game progressively harder by not allowing the dog watch the victim run away,” explains Dave Leffler, Breckenridge's ski patroller and head of the avy dog program, who has owned, trained and raised many of them. Eventually, the trainers “dig an open hole in the snow to duck out of sight and gradually turn the hole into a cave where the dog has to dig to get the victim,” explains Leffler.
By the time he is three, Lume, like Huckleberry, will be a fully trained avy pup and will join seven other avy dogs on Breckenridge ski patrol team. Some of the team members, both human and canine, are also certified to work with Colorado Rapid Avalanche Deployment, a coordinated response team that works with the Summit County Sheriff’s office for avalanche emergencies outside of the ski slopes’ boundaries.
There have been 19 avalanche deaths in the U.S. this season, according to avalanche.org, which tracks slides; eight in Colorado. During the entirety of last season there were 17. Avalanche season runs from November through June, but avalanches can occur year-round.
High tech and high stakes
Complementing avy dogs’ ability to smell people buried in a slide, avalanche detection, rescue and recovery is becoming increasingly high tech. There are transceivers, signal locators, ground scanners and drones, which are considered “games changers” by many in avalanche rescue and recovery
For a person buried in an avalanche, the chance of survival plummets after 20 minutes, so every moment counts.
A drone can provide thermal imaging of objects caught in a slide; what looks like a rock from far away might be a human with a heat signature. Transceivers, also known as beacons, send a signal from an avalanche victim to a companion. Signal locators, like RECCO reflectors which are often sewn directly into gear, can echo back a radar signal sent by a detector; most ski resorts have RECCO detector units.
Research suggests that Ground Penetrating Radar (GPR), an electromagnetic tool used by geophysicists to pull images from inside the ground, could be used to locate an avalanche victim. A new study from the Department of Energy’s Sandia National Laboratories suggests that a computer program developed to pinpoint the source of a chemical or biological terrorist attack could also be used to find someone submerged in an avalanche. The search algorithm allows for small robots (described as cockroach-sized) to “swarm” a search area. Researchers say that this distributed optimization algorithm can help find avalanche victims four times faster than current search mechanisms. For a person buried in an avalanche, the chance of survival plummets after 20 minutes, so every moment counts.
An avy dog in training is picking up scent
Sarah McLear
While rescue gear has been evolving, predicting when a slab will fall remains an emerging science — kind of where weather forecasting science was in the 1980s. Avalanche forecasting still relies on documenting avalanches by going out and looking,” says Ethan Greene, director of the Colorado Avalanche Information Center (CAIC). “So if there's a big snowstorm, and as you might remember, most avalanches happened during snowstorms, we could have 10,000 avalanches that release and we document 50,” says Greene. “Avalanche forecasting is essentially pattern recognition,” he adds--and understanding the layering structure of snow.
However, determining where the hazards lie can be tricky. While a dense layer of snow over a softer, weaker layer may be a recipe for an avalanche, there’s so much variability in snowpack that no one formula can predict the trigger. Further, observing and measuring snow at a single point may not be representative of all nearby slopes. Finally, there’s not enough historical data to help avalanche scientists create better prediction models.
That, however, may be changing.
Last year, an international group of researchers created computer simulations of snow cover using 16 years of meteorological data to forecast avalanche hazards, publishing their research in Cold Regions Science and Technology. They believe their models, which categorize different kinds of avalanches, can support forecasting and determine whether the avalanche is natural (caused by temperature changes, wind, additional snowfall) or artificial (triggered by a human or animal).
With smell receptors ranging from 800 million for an average dog, to 4 billion for scent hounds, canines remain key to finding people caught in slides.
With data from two sites in British Columbia and one in Switzerland, researchers built computer simulations of five different avalanche types. “In terms of real time avalanche forecasting, this has potential to fill in a lot of data gaps, where we don't have field observations of what the snow looks like,” says Simon Horton, a postdoctoral fellow with the Simon Fraser University Centre for Natural Hazards Research and a forecaster with Avalanche Canada, who participated in the study. While complex models that simulate snowpack layers have been around for a few decades, they weren’t easy to apply until recently. “It's been difficult to find out how to apply that to actual decision-making and improving safety,” says Horton. If you can derive avalanche problem types from simulated snowpack properties, he says, you’ll learn “a lot about how you want to manage that risk.”
The five categories include “new snow,” which is unstable and slides down the slope, “wet snow,” when rain or heat makes it liquidly, as well as “wind-drifted snow,” “persistent weak layers” and “old snow.” “That's when there's some type of deeply buried weak layer in the snow that releases without any real change in the weather,” Horton explains. “These ones tend to cause the most accidents.” One step by a person on that structurally weak layer of snow will cause a slide. Horton is hopeful that computer simulations of avalanche types can be used by scientists in different snow climates to help predict hazard levels.
Greene is doubtful. “If you have six slopes that are lined up next to each other, and you're going to try to predict which one avalanches and the exact dimensions and what time, that's going to be really hard to do. And I think it's going to be a long time before we're able to do that,” says Greene.
What both researchers do agree on, though, is that what avalanche prediction really needs is better imagery through satellite detection. “Just being able to count the number of avalanches that are out there will have a huge impact on what we do,” Greene says. “[Satellites] will change what we do, dramatically.” In a 2022 paper, scientists at the University of Aberdeen in England used satellites to study two deadly Himalayan avalanches. The imaging helped them determine that sediment from a 2016 ice avalanche plus subsequent snow avalanches contributed to the 2021 avalanche that caused a flash flood, killing over 200 people. The researchers say that understanding the avalanches characteristics through satellite imagery can inform them how one such event increases the magnitude of another in the same area.
Avy dogs trainers hide in dug-out holes in the snow, teaching the dogs to find buried victims
Sarah McLear
Lifesaving combo: human tech and Mother Nature’s gear
Even as avalanche forecasting evolves, dogs with their built-in rescue mechanisms will remain invaluable. With smell receptors ranging from 800 million for an average dog, to 4 billion for scent hounds, canines remain key to finding people caught in slides. (Humans in comparison, have a meager 12 million.) A new study published in the Journal of Neuroscience revealed that in dogs smell and vision are connected in the brain, which has not been found in other animals. “They can detect the smell of their owner's fingerprints on a glass slide six weeks after they touched it,” says Nicholas Dodman, professor emeritus at Cummings School of Veterinary Medicine at Tufts University. “And they can track from a boat where a box filled with meat was buried in the water, 100 feet below,” says Dodman, who is also co-founder and president of the Center for Canine Behavior Studies.
Another recent study from Queens College in Belfast, United Kingdom, further confirms that dogs can smell when humans are stressed. They can also detect the smell of a person’s breath and the smell of the skin cells of a deceased person.
The emerging avalanche-predicting human-made tech and the incredible nature-made tech of dogs’ olfactory talents is the lifesaving “equipment” that Leffler believes in. Even when human-made technology develops further, it will be most efficient when used together with the millions of dogs’ smell receptors, Leffler believes. “It is a combination of technology and the avalanche dog that will always be effective in finding an avalanche victim.”
Living with someone changes your microbiome, new research shows
Some roommate frustration can be expected, whether it’s a sink piled high with crusty dishes or crumbs where a clean tabletop should be. Now, research suggests a less familiar issue: person-to-person transmission of shared bacterial strains in our gut and oral microbiomes. For the first time, the lab of Nicola Segata, a professor of genetics and computational biology at the University of Trento, located in Italy, has shown that bacteria of the microbiome are transmitted between many individuals, not just infants and their mothers, in ways that can’t be explained by their shared diet or geography.
It’s a finding with wide-ranging implications, yet frustratingly few predictable outcomes. Our microbiomes are an ever-growing and changing collection of helpful and harmful bacteria that we begin to accumulate the moment we’re born, but experts are still struggling to unravel why and how bacteria from one person’s gut or mouth become established in another person’s microbiome, as opposed to simply passing through.
“If we are looking at the overall species composition of the microbiome, then there is an effect of age of course, and many other factors,” Segata says. “But if we are looking at where our strains are coming from, 99 percent of them are only present in other people’s guts. They need to come from other guts.”
If we could better understand this process, we might be able to control and use it; perhaps hospital patients could avoid infections from other patients when their microbiome is depleted by antibiotics and their immune system is weakened, for example. But scientists are just beginning to link human microbiomes with various ailments. Growing evidence shows that our microbiomes steer our long-term health, impacting conditions like obesity, irritable bowel syndrome, type 2 diabetes, and cancer.
Previous work from Segata’s lab and others illuminated the ways bacteria are passed from mothers to infants during the first few months of life during vaginal birth, breastfeeding and other close contact. And scientists have long known that people in close proximity tend to share bacteria. But the factors related to that overlap, such as genetics and diet, were unclear, especially outside the mother-baby dyad.
“If we look at strain sharing between a mother and an infant at five years of age, for example, we cannot really tell which was due to transmission at birth and which is due to continued transmission because of contact,” Segata says. Experts hypothesized that they could be caused by bacterial similarities in the environment itself, genetics, or bacteria from shared foods that colonized the guts of people in close contact.
Strain sharing was highest in mother-child pairs, with 96 percent of them sharing strains, and only slightly lower in members of shared households, at 95 percent.
In Italy, researchers led by Mireia Valles-Colomer, including Segata, hoped to unravel this mystery. They compared data from 9,715 stool and saliva samples in 31 genomic datasets with existing metadata. Scientists zoomed in on variations in each bacterial strain down to the individual level. They examined not only mother-child pairs, but people living in the same household, adult twins, and people living in the same village in a level of detail that wasn’t possible before, due to its high cost and difficulties in retrieving data about interactions between individuals, Segata explained.
“This paper is, with high granularity, quantifying the percent sharing that you expect between different types of social interactions, controlling for things like genetics and diet,” Gibbons says. Strain sharing was highest in mother-child pairs, with 96 percent of them sharing strains, and only slightly lower in members of shared households, at 95 percent. And at least half of the mother-infant pairs shared 30 percent of their strains; the median was 12 percent among people in shared households. Yet, there was no sharing among eight percent of adult twins who lived separately, and 16 percent of people within villages who resided in different households. The results were published in Nature.
It’s not a regional phenomenon. Although the types of bacterial strains varied depending on whether people lived in western and eastern nations — datasets were drawn from 20 countries on five continents — the patterns of sharing were much the same. To establish these links, scientists focused on individual variations in shared bacterial strains, differences that create unique bacterial “fingerprints” in each person, while controlling for variables like diet, demonstrating that the bacteria had been transmitted between people and were not the result of environmental similarities.
The impact of this bacterial sharing isn’t clear, but shouldn’t be viewed with trepidation, according to Sean Gibbons, a microbiome scientist at the nonprofit Institute for Systems Biology.
“The vast majority of these bugs are actually either benign or beneficial to our health, and the fact that we're swapping and sharing them and that we can take someone else's strain and supplement or better diversify our own little garden is not necessarily a bad thing,” he says.
"There are hundreds of billions of dollars of investment capital moving into these microbiome therapeutic companies; bugs as drugs, so to speak,” says Sean Gibbons, a microbiome scientist at the Institute for Systems Biology.
Everyday habits like exercising and eating vegetables promote a healthy, balanced gut microbiome, which is linked to better metabolic and immune function, and fewer illnesses. While many people’s microbiomes contain bacteria like C. diff or E. coli, these bacteria don’t cause diseases in most cases because they’re present in low levels. But a microbiome that’s been wiped out by, say, antibiotics, may no longer keep these bacteria in check, allowing them to proliferate and make us sick.
“A big challenge in the microbiome field is being able to rationally predict whether, if you're exposed to a particular bug, it will stick in the context of your specific microbiome,” Gibbons says.
Gibbons predicts that explorations of microbe-based therapeutics will be “exploding” in the coming decades. “There are hundreds of billions of dollars of investment capital moving into these microbiome therapeutic companies; bugs as drugs, so to speak,” he says. Rather than taking a mass-marketed probiotic, a precise understanding of an individual’s microbiome could help target the introduction of just the right bacteria at just the right time to prevent or treat a particular illness.
Because the current study did not differentiate between different types of contact or relationships among household members sharing bacterial strains or determine the direction of transmission, Segata says his current project is examining children in daycare settings and tracking their microbiomes over time to understand the role genetics and everyday interactions play in the level of transmission that occurs.
This relatively newfound ability to trace bacterial variants to minute levels has unlocked the chance for scientists to untangle when and how bacteria leap from one microbiome to another. As researchers come to better understand the factors that permit a strain to establish itself within a microbiome, they could uncover new strategies to control these microbes, harnessing the makeup of each microbiome to help people to resist life-altering medical conditions.