The Food and Drug Administration on Thursday issued a safety warning following the death of a patient who contracted a drug resistant bacteria that was transmitted during an experimental fecal transplant.

Another patient also fell ill after receiving a transplant, the FDA said. Both adults, who the agency did not identify, had compromised immune systems.

The stool used for both patients' transplants was obtained from the same donor, according to the FDA, and was not tested for E.coli bacteria that produced the beta-lactamase enzyme. An FDA spokeswoman could not immediately provide more details on the death.

"While we support this area of scientific discovery, it's important to note that FMT does not come without risk," Dr. Peter Marks, director of the FDA's Center for Biologics Evaluation and Research, said in a statement. The FDA said the patient who died received an experimental fecal microbiome transplant, or FMT. "We therefore want to alert all health care professionals who administer FMT about this potential serious risk so they can inform their patients," he said.

The FDA said certain donor screening and stool testing protections are needed for any experimental use of fecal microbiome transplants as a result of the patients falling ill.

Fecal microbiome transplants, also known as stool transplants, are when fecal bacteria from healthy donors are transplanted into a recipient. The FDA has permitted the experimental transplants to be used for certain conditions since 2013.