Faecal transplants can bring the promise of an improved microbiome in ill patients, but a new report suggests they are not risk-free.

In a faecal transplant, donated faecal matter is processed and put into capsules for patients to swallow. Once in the gut, the capsules dissolve, releasing new, healthy bacteria into the gut.

A variety of harmful bacteria

But doctors from Massachusetts General Hospital in Boston reported that two patients who received faecal transplants suffered infections from drug-resistant E. coli, and one of them died from their infection.

Although donors and donated matter are typically tested for a variety of harmful bacteria, at the time of these transplants, drug-resistant extended spectrum beta-lactamase E. coli wasn’t one of those germs tested. Now it is. Continually adding germs to screen is one way to reduce future risk, the researchers noted.

“I think screening is important, but it’s a work in progress,” explained lead researcher Dr Elizabeth Hohmann, an investigator in the division of infectious diseases at Mass General.

“It’s not a panacea, because we can’t screen for everything,” she said. “There could still be things there that we’re transmitting which might cause medical consequences down the road.”

Hohmann believes that patients need to weigh the benefits of a faecal transplant against the possible risks.

“I have patients tell me they don’t want to have a faecal transplant because of the risk of infection, because of the ‘yuck’ factor, because intestinal microbiome are linked to weight and they’re worried about becoming overweight,” she said. “It’s a personal decision that people need to talk through with their physician.”

Used for other conditions

Faecal transplants were first developed to treat infection with Clostridioides difficile (C. diff), a common bacterial infection seen in hospitals and nursing homes.

Antibiotics are the usual treatment for C. diff, but the treatment often destroys the good bacteria along with the bad, and C. diff can return. That’s where faecal transplants can help.

The two patients in this report were enrolled in studies to see if fecal transplants could be used for other conditions.

The first patient, a 69-year-old man with liver damage from hepatitis C, was in a study to see if faecal transplants could improve brain function in patients with liver disease. When this patient came down with drug-resistant E. coli, he was treated with antibiotics and recovered.

The second patient, a 73-year-old man with leukaemia, was in a study to improve the microbiome at the time he was receiving a stem-cell transplant.

This patient developed E. coli infection shortly after the faecal transplant, and died of complications from the infection.

Once the US Food and Drug Administration was notified of these outcomes, they stopped both studies and issued a warning. Both studies are underway again with added precautions, Hohmann said.

Balance benefit and risk

She also said that new methods of faecal transplants are being developed, including one that would not rely on donors but on bacteria grown in the lab, which would all but eliminate the odds of transplanting harmful germs.

The report was published online in the New England Journal of Medicine.

Dr Martin Blaser is chair of the human microbiome at Rutgers University, in Piscataway, New Jersey. He said, “Any time we give people biological products from people, there is the risk of transmitting infectious agents.”

The more this is done, the more agents will be discovered, said Blaser, who wrote an accompanying editorial.

“On the other hand, there are important diseases for which treatment is not good enough, and we need to find new treatments. Scientists and doctors need to balance benefit and risk,” he said.

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