SEATTLE — Conventional wisdom says it takes 15 years for a medical therapy, once proven safe and effective, to be widely accepted by the medical profession.

In the case of one particular treatment, however, a growing cadre of doctors and patients turned conventional wisdom on its head, enthusiastically adopting a procedure before the evidence was in — so enthusiastically, in fact, that the Food and Drug Administration was recently forced to rescind its restrictions.

The treatment, now widely employed against recurrent attacks by a nasty intestinal bug known as Clostridium difficile and tested on Crohn’s disease and colitis, is one you’ll likely never see advertised on TV: the fecal microbiota transplant, politely known as the FMT.

Acronym or no, a rose is a rose is a rose, and a poop transplant, likewise.

Born of desperation on the part of patients and their doctors, an infusion of fecal material from a healthy donor has risen from folk wisdom to near-mythical status. Despite a certain “yuk” factor, an increasing number of patients have undergone the procedure in top hospitals, clinics and even in their homes, doctors say.

In a first-of-its-kind research study just concluded at Seattle Children’s, the treatment significantly helped kids with Crohn’s.

So far, the transplant’s biggest success has been against the bug commonly known as C. diff, which now strikes upward of half a million people a year in the U.S. With the emergence of a particularly virulent strain, it has been deemed a “global public health challenge” by the Centers for Disease Control and Prevention.

The infection can cause relentless diarrhea, a potentially life-threatening complication, particularly for older people. This notorious bacterium typically proliferates when a person’s natural intestinal bacteria — which normally outnumber and marginalize such bad actors — are laid low, most often by antibiotics.

In theory, FMT repopulates the compromised intestine with a healthy mix of fecal bacteria that kicks the bad bugs’ butts. But until recently, with scant first-rate research, doctors intent on helping their patients had to rely mostly on anecdotal evidence.

“I became one of those desperate doctors,” said Dr. Christina Surawicz, a gastroenterologist at Harborview Medical Center, who first used the treatment in 2004. No conventional medications were working for her patient, who had been miserable for nine months. “I took a leap of faith.”

The transplant, taken from the patient’s husband and given via colonoscopy, worked. Surawicz, long a researcher of C. diff, wasn’t the first locally to do such a transplant, but became known as a pioneer. Around town — and the country — a small underground of gastroenterologists and infectious disease specialists began experimenting with the procedure, making up protocols as they went.

There was indeed a “yuk” factor, particularly in the early years. “Most people would say, ‘You’re going to do whaaaat?’” recalled Dr. Francis Riedo, an infectious-disease specialist at EvergreenHealth in Kirkland. “But by the time we saw those patients, they were so miserable, so desperate, they would try anything.”

Some hospitals wouldn’t allow the procedure, so doctors instructed their patients on home administration through an enema — likely a less-than-ideal method. And there was wide variation in methods, with some doctors favoring tubes through the nose to deliver a slurry to the upper gastrointestinal region, while others favored the lower route.

Early this summer, the FDA firmly declared poop a “biologic” and warned doctors they must acquire an “Investigational New Drug” research permit to administer it.

Doctors pounded the FDA. They complained that having to go through a cumbersome research process threatened to add costs and limit access for seriously ill patients. Also, more might be tempted to try the procedure on their own, without such safeguards as donor testing.

Just two months later, the agency relented, saying doctors didn’t need a permit to administer a fecal transplant to patients with recurrent C. diff.

“It’s clearly the single most effective therapy for C. diff. Nothing comes close to the rate of fecal transplantation — nothing,” says Riedo.

Who woulda thought a poop transplant would become so popular? Linda Bollen, 71, of Bothell, would like a chance to explain why. Her bout with C. diff began in April 2011, when she contracted pneumonia and ended up in intensive care and later a rehabilitation facility. Throughout her ordeal, she needed multiple doses of antibiotics. When she came home, C. diff got the best of her gut.

The diarrhea began in June, and then came doctors and more doctors, drugs and more drugs — including very expensive drugs. She ended up in the hospital again, dehydrated from the diarrhea. Then pneumonia, again. And C. diff, again.

Finally, nearly a year later, her infectious disease doctor at Evergreen proposed a radical shift in treatment.

Desperate, she agreed. “I said, ‘Hey, I’ll do anything to get rid of this,’” she recalled.

“I’ve been fine ever since — not even a cold,” says Bollen. “I would totally recommend this for anybody — 100 percent. You feel better immediately.”

Another doctor told her some patients say they’d rather die than have “that” done. “I don’t understand that. If it’s from a loved one, what’s the difference?”

Her husband, she said, was happy to donate. “He’d seen what I’ve gone through.”

And she couldn’t resist making the obvious joke to her doctor about what she was finally happy to take from her husband.