As a “yuk factor,” few topics can compete with poop. Also known as human waste, excrement, feces or fecal matter.

Poop being used as medicine scores even higher on the socially unacceptable scale. Yet it can be effective treatment for an infection that causes nonstop diarrhea, a sometimes fatal condition. A medical procedure called gut refloralization (GR) — also sometimes called fecal microbial transplant (FMT) — involves transplanting a microscopic amount of human stool from a healthy person into the intestines of an unhealthy person. It can be thought of as something like a kidney transplant, given to a patient in need of a healthy organ, by a donor who has one to spare. Or donating blood. Like other transplant methods, it involves replacing a body part that’s not working with one that is.

Gut refloralization, or fecal transplant, has been FDA approved only for experimental treatment in Clostridium difficile infection recurring cases. Almost half a million CDI cases develop among U.S. patients each year. More than 20,000 deaths are directly attributable to CDI, which the U.S. Centers for Disease Control calls “a major health threat.”

“This is not a new idea,” says Dr. Sabine Hazan-Steinberg, a Ventura Community Memorial Health System gastroenterologist who treats patients with gut refloralization. “It has appeared in the annals of medicine throughout history, including 4th-century Chinese medicine that included using excrement to treat diarrhea.”

There are records of fecal transplantation from the 1300s, and veterinarians have for centuries treated diarrheic horses with the technique. Bedouins were rumored to have treated dysentery with camel stool. In 1958, four human patients’ lives were saved by fecal transplant, yet it failed to gain acceptance in the U.S. due to public aversion to the concept. People have shown disdain for any scientific advance that seems too queasy or “unnatural.”

Gut refloralization is currently available only as an experimental procedure; a group of physicians including Hazan-Steinberg are part of the U.S. Food and Drug Administration’s ongoing investigation into how it works. It is not yet FDA approved as being safe; the experimental results are being gathered to understand why it is successful for some patients. So far, the U.S. National Institutes of Health describes GR as “reasonably safe and effective.”

Poop is full of bacteria, and not all bacteria are bad. Some bacterial strains can be beneficial.

“In fact, the human body is home to a variety of microbes that help keep us healthy,” Hazan-Steinberg explained. She is treating patients with experimental GR under the current FDA investigation. Physicians can perform transplants as long as patients understand and agree that the procedure is experimental. The treatment is not widely available, and is only partially covered by some insurance companies.

“I have a 99-percent success rate because I find the right donors,” Hazan-Steinberg said. “The process involves taking the fecal material of a healthy donor.”

Although GR and FMT are being tested in clinical trials for illnesses including Irritable Bowel Syndrome, urinary tract infections, ulcerative colitis and some cancers, so far the FDA has only approved its experimental use in cases of recurrent Clostridium difficile infection, or CDI, which causes debilitating diarrhea. Almost half a million CDI cases develop among U.S. patients each year. More than 20,000 deaths are directly attributable to CDI, which the U.S. Centers for Disease Control calls “a major health threat.”

Bad bacteria in a person’s gut can be harmful, while good bacteria fight off disease. Bacteria are microbes, and microbes gathered into groups are called a microbiome. A person’s gut bacteria are called that individual’s personal microbiome. A person’s microbiome is unique to them, based on what they eat, their inherited genes, their lifestyle choices, where they live, how much pollution they inhale and more.

“The types, quantity and balance of microbes in your unique microbiome can affect your susceptibility or resistance to a variety of health issues,” Hazan-Steinberg explained.

Some experts have described the personal microbiome “as unique to an individual as a fingerprint.” This is an important part of the FDA investigation into whether fecal transplants can be declared “safe.”

An individual person’s microbiome is “an accumulation of bacterial DNA, viral DNA, and fungal DNA,” Hazan-Steinberg said. To achieve successful GR, she does detailed patient analysis, as well as meticulous, precise donor selection. There must be a specific match between patient and donor.

“Finding donors is the most critical, and complex, aspect of treatment,” in Hazan-Steinberg’s experience. “The most important aspect is to precisely match the donor.”

Every human being has a unique microbiome in their gut. This is why Hazan believes finding an appropriate donor is extremely complicated and critical to healing. Donor match is the most important factor because if it is not precise, “the same thing that cures a disease can also cause disease,” she said.

Some scientists see it differently: “Does the donor matter?” is the title of a recent study published in the journal Gastroenterology. There are some studies showing that the choice of donor does not significantly impact the success of GR treatment for CDI. The study described how donor factors do not always drive successful treatment of CDI, but rather that patient factors — including precise diagnoses of patients’ conditions — are more likely causing cures of CDI.

The scent of poop, paired with a lifetime of bandaging cuts and wounds to keep bacteria out, prevents many people from understanding that most bacteria in the gut keeps people healthy. But microbiomes containing good bacteria help to digest food, produce vitamins and keep the immune system ready to pounce on disease.

Hazan-Steinberg transplants fecal matter from healthy donors into the intestines of patients suffering from recurrent CDI. Although it is too distasteful to fit into mainstream thinking for most people, for patients who are dying from CDI, any cutting-edge solution is welcome.

Scientists are also researching fecal transplant’s potential to treat hypertension, obesity, cardiovascular conditions and some cancers. There is some initial evidence that for other diseases, the donor’s health does matter significantly.

Some new companies offer processed, frozen stool material from volunteers or paid donors that is not always matched to specific CDI patients. Operating within the FDA’s current experimental requirements, they maintain collections of stool that work somewhat like blood banks. Paid donors receive about $40 per stool donation, and one report described how a donor could make $13,000 per year.

“Many of those companies are not operated by gastrointestinal physicians or specialists,” Hazan-Steinberg said. “They do not know how to assess the material and they do not know what they are looking at.” A one-stool-fits-all approach can be dangerous. Imprecise stool collection might be contaminated by the presence of cancer, hepatitis, HIV/AIDS or other infections within a donor’s microbiome.

A recent New York Times article, “What is a fecal transplant and why would I want one?”, described the experimental treatments available from OpenBiome, one of several new companies that maintain stool banks, where stool is available for treatment of CDI. OpenBiome’s donor selection process is extremely rigorous. It includes a 200-point questionnaire, medical exams, and extensive blood and stool screens. OpenBiome screens for potential disease agents in the gut microbiome. Only 2.8 percent of potential donor applicants are accepted.

GR donors are often people with healthy lifestyles, but researchers are also investigating who might be the best donors, and one area of inquiry concerns whether people who have fought off serious disease, including perhaps homeless people who survive harsh weather, poor food and lack of healthcare, might have microbiomes that are stronger even than people who live a super-healthy lifestyle. One study questions what might constitute a “Super Donor.” The answer is still unknown and the object of scientific investigation. At this point, the donor selection process at OpenBiome and other stool bank companies is extremely stringent with regard to donor health.

“Generally, there’s some research showing that the microbiome may mediate our susceptibility to infection, both in the gut and elsewhere in the body,” OpenBiome’s Clinical Program Director, Dr. Majdi Osman, told the VCReporter. “The science is still evolving, so we take a conservative approach when screening our donors to eliminate any known risk factors for susceptibility to infection.”

The warning “Don’t try this at home” might seem self-evident, but Hazan-Steinberg has seen blatant cases of abuse. “I’ve heard about masseuses claiming they can treat disease with gut refloralization,” she said. Inserting another person’s feces into one’s own intestinal tract, without expert medical training and experience, could not only damage the intestines but also be fatal.

Hazan-Steinberg is the founder of Ventura Clinical Trials and the Malibu Specialty Center. She said that for more than 20 years she has tested new experimental procedures and 300 clinical-trial treatments for gastrointestinal and infectious diseases, Hepatitis C, pancreatic cancer, cardiovascular and endocrine disorders. She is launching a new venture, ProGenaBiome, where one of her goals will be investigating the microbiomes of homeless people, to assess what enables them to endure the harsh consequences of the outdoors or build resilience against disease. Because no pharmaceutical company is likely to finance research into potential GR stool donors among the homeless population, ProGenaBiome will be working with homeless-support organizations to forge funding strategies.

Few medical advances have spawned as many bad headlines as GR has, including “Butting up against new science,” “Novel treatment faces headwinds” and “A process of elimination.” But dying patients whose lives it has saved are not laughing.

“New research will change the way we look at disease,” Hazan-Steinberg said.