A man who died after receiving a fecal transplant was infected with an antibiotic-resistant strain of E. coli, it has emerged.
The 73-year-old was taking part in an experiment to see if a 'poo transplant', as it's commonly known, could be useful in treating gut issues related to liver disease. In June the US Food and Drug Administration announced two patients in the trial had fallen seriously ill, and one had died.
It's now been revealed E. coli was the cause, in a study of the case published in the New England Journal of Medicine.
Fecal transplants involve ingesting - orally or via an enema - microbes taken from the stool of a healthy person. They've been shown to help with boosting diversity in patient gut biomes, and can treat certain types of infections.
Both patients in the Massachusetts General Hospital trial received bacteria taken from the same person. Eight days later, the 73-year-old began suffering fever, chills and an "altered mental status". His immune system went into overdrive and he developed sepsis and died two days later.
"While we support this area of scientific discovery, it's important to note that [fecal transplant] does not come without risk," an FDA spokesperson said in June, after the death was first made public.
"We've become aware of infections with multi-drug resistant organisms after patients received investigational [fecal transplant], including one patient death. We therefore want to alert all health care professionals who administer [fecal transplant] about this potential serious risk so they can inform their patients."
The stool which supplied the bacteria hadn't been tested, it turned out. All 22 patients in the trial tested positive for E. coli, but most didn't fall ill.
Both men who did however had weakened immune systems. The man who died was taking immunosuppressant drugs after a stem cell transplant, and the one who survived - barely - had advanced cirrhosis.
"Enhanced donor screening to limit the transmission of microorganisms that could lead to adverse infectious events and continued vigilance to define the benefits and risks of FMT across different patient populations are warranted," the authors of the study said.
Fecal transplant science is in its infancy, but researchers at Auckland's Liggins Insitute believe it could help treat a range of illnesses, including irritable bowel syndrome, diabetes and asthma.
"The last two decades have seen a growing list of medical conditions associated with changes in the microbiome - bacteria, viruses and fungi, especially in the gut," the institute's Dr Justin O'Sullivan said earlier this year.
"In fact, we know already that changes to the gut microbiome can contribute to disease, based on studies in germ-free mice as well as clinical improvement in human patients following restoration of the gut microbiome by transplanting stool from a healthy donor."