Poop transplants work as well as antibiotics to treat a common and deadly cause of diarrhea, and perhaps even better, researchers reported Saturday.

Their small and unusual study suggests that doctors should try fecal transplants right off when patients in the hospital get infected with Clostridium difficile, a frequent cause of diarrhea in frail and sick patients.

Their carefully cultivated and curated samples cured half the patients who tried them right away, the Norwegian team reported in the New England Journal of Medicine.

And most of those that weren’t cured with a single transplant saw their diarrhea clear up when they were given antibiotics later.

“This was a small trial, but the results suggest that fecal microbiota transplantation may be an alternative to antibiotic therapy in primary C. difficile infection,” Dr. Frederick Juul of Oslo University Hospital and colleagues wrote in a letter to the New England Journal.

C. difficile, C. diff for short, is an increasingly common danger to patients in the hospital.

C. difficile infections kill 29,000 Americans a year and make 450,000 sick in the U.S. alone, according to the Centers for Disease Control and Prevention.

It causes unremitting diarrhea, which can weaken patients being treated for pneumonia, cancer and other illnesses.

Right now, antibiotics can make patients even sicker because they kill not only the C. difficile, but so-called good bacteria that keep things in balance. Once other bacteria are killed off, C. diff, as it’s commonly known, can come back and even proliferate — without competition.

Poop transplants aim to restore the balance with healthy bacteria.

They’ve been used for years, but there are disagreements over how best to deliver the fecal matter and also on when to use them.

The Food and Drug Administration allows doctors to use them if patients have had repeated C. diff infections that haven’t been helped by antibiotics.

The Infectious Diseases Society of America (IDSA) and the Society for Healthcare Epidemiology of America (SHEA) recommend using them as a last-resort treatment after repeated bouts of C. diff.

But what if a poop transplant is the first treatment?

Juul’s team tried it in a group of 20 patients. Nine got poop transplants at the first sign of C. diff-related diarrhea, and 11 got the antibiotic metronidazole.

Five out of nine who got the fecal transplant were cured by a single transplant delivered by enema, and five of the 11 who got antibiotics were cured, the team reported. Their findings are being presented and discussed at a meeting of gastroenterologists called Digestive Disease Week.

Four days after the fecal transplant, three of the patients who still had diarrhea got antibiotics and two of them were cured. But giving more antibiotics to the six patients who got drugs to start with did not help them recover, the researchers said.

That might suggest that pre-treating with fecal transplants might help make antibiotics work better in some cases, but this would have to be shown in larger trials.

For this trial, the researchers gave each patient a single enema using fecal bacteria taken from a specially saved and frozen stool sample from a healthy donor on a Western diet. “Since 1994, the sample has been continuously cultivated in a laboratory under strict anaerobic conditions,” they wrote.

That’s important. Bacteria exposed to air develop differently from bacteria that have not been exposed to outside air. The inside of the colon is pretty much air-free.

The stool has also been kept frozen, which means it has no exposure to any antibiotic resistance that may have developed and spread in bacteria since 1994. A company called Achim Biotherapeutics makes the fecal transplant product used for the study.

The team’s now testing their method in more patients.

Gut experts in the U.S. have said, however, that the antibiotic used in this study is not particularly effective against C. diff any more. IDSA and SHEA updated their guidelines in February, recommending that doctors stop using it for C. diff and instead use either vancomycin or fidaxomicin.

It’s not clear how poop transplants compare to those drugs.

It’s also not clear if repeated fecal transplants would help patients who don’t respond immediately to the first one.