Fecal transplants are more likely than antibiotics to save lives and prevent deadly bloodstream infections in patients sickened by a pernicious and persistent bacteria, a study published Monday finds.

The procedure, also called fecal microbiota transplantation, has long been used to treat bacterial infections caused by Clostridium difficile, or C. diff, that don’t respond to antibiotics. FMT involves transplanting processed stool from a healthy individual into the gut of a sick patient.

This isn’t the first study to find that FMT might work better than antibiotics to cure C. diff; however, it’s the first to look at the treatment’s effects on complications that can stem from the infection.

“Before this study, we knew that FMT was more effective than antibiotics in curing recurrent C. difficile infection, but now we know that it is also more effective in preventing C. diff-related complications,” said the study’s lead author, Dr. Gianluca Ianiro, a microbiome and FMT specialist at the Fondazione Policlinico Gemelli IRCCS in Rome.

C. diff 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.

Ianiro’s study, published in the Annals of Internal Medicine, found that compared with antibiotics, FMT increased patients’ survival by more than 30 percent, cut the length of hospital stays in half, and reduced the risk of bloodstream infection, or sepsis, by fourfold.

Ianiro suspects there are several factors explaining the lower rates of bloodstream infection in patients who received FMT. They include a shorter stay in the hospital, which is known to reduce the risk of bloodstream infections; curing the original infection, which lowers the risk of bacteria leaking from the intestines into the bloodstream; and the possibility that FMT might lead to fewer multidrug-resistant bacteria popping up in the guts of patients, Ianiro said.

The theory behind the use of FMT to combat C. diff is fairly simple: by transplanting microorganisms from a healthy donor, the gut microbiome of the patient is restored to normal, which creates an environment that is unfriendly to the potentially deadly C. diff bacteria.

To explore whether FMT might affect the risk of a deadly bloodstream infection, Ianiro and his colleagues followed two groups of C. diff patients for 90 days: 109 who were treated with FMT and 181 who received antibiotics.

Five patients, or roughly 5 percent, from the FMT group and 40 patients, or 22 percent, in the antibiotic-treated group developed bloodstream infections.

Further analysis of similar patients — such as those who had a similar number of prior C. diff recurrences — showed that the FMT group had 14 fewer days in the hospital and a 32 percent increase in overall survival at 90 days, compared with the antibiotic group.

The new study “is the first to look at the effectiveness of FMT versus antibiotics at preventing a known complication of C. diff: bloodstream infections,” said Dr. Dan Uslan, the clinical chief of infectious diseases at UCLA Health in Los Angeles.

Bloodstream infections, which can lead to sepsis and death, can occur in people with C. diff when the colon gets severely inflamed, and bacteria leak out into the blood, Uslan said in an email.

Still, the study alone is not enough to suggest that doctors use FMT to lower the risk of bloodstream infections, said Dr. Purna Kashyap, an associate professor of medicine, physiology and biomedical engineering and co-director of the Microbiome Program at the Mayo Clinic.

“As the authors already acknowledge, this is an observational study, which is good to generate the hypothesis, but it will need to be tested in a more controlled manner, such as with a randomized-controlled study,” Kashyap said in an email.

Dr. Alexander Khoruts, a professor of medicine and the medical director of the Microbiota Therapeutics Program at the University of Minnesota, agreed that more research is needed to confirm the new findings.

That said, “the group who received FMT was actually sicker than the one treated with antibiotics,” Khoruts said. “They had a greater history of past C. diff infections and yet they ended up with fewer deaths and fewer bloodstream infections at 90 days.”

Despite the potential benefits from FMT, it “may not be for everyone,” Uslan said. “There are important risks.”

In June, the FDA announced that one patient had died and another was sickened from fecal transplants that contained drug-resistant bacteria.

Uslan acknowledged that potential concern for transmitting infectious agents, but added that “that risk can be reduced significantly by screening the donor material.”

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