For poo transplants, frozen is as good as fresh
Fecal matter transplants (FMT) might elicit a giggle from the uninitiated. But for many, these donations are life-changing, if not outright life-saving.
A new study helps confirm that frozen faecal donations work as well as fresh ones, which could help make the treatments cheaper and more widely available.
And that's a good thing, because FMT is being tested to fix everything from ulcers to obesity.
FMT is exactly what it sounds like: Faecal matter from a healthy donor is given to the patient, usually via enema or orally.
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For those suffering from chronic infections of the bacterium Clostridium difficile, these transplants can turn life-threatening diarrhoea into healthy bowel movements.
When the bacteria from a healthy gut enter the sick patient, they can outcompete the dangerous microbes – even when antibiotics have failed to kill them before. Once the C. difficile is beaten down, normal gastrointestinal function can resume.
The new study, led by McMaster University's Christine Lee and published in JAMA, found that patients given donations that had been frozen for up to 30 days fared just as well as those given fresh samples.
"One of the major challenges to maintaining FMT is donor availability," Lee said.
FMT donors must have a perfectly healthy gut microbiome, lest their donation infect an ill patient with even more harmful bacteria. Screening all of those potential donors is costly, and can take up to 14 days per person. If samples can be stored frozen, doctors can screen fewer patients and stock up on the good stuff.
"We're very pleased by the findings, but we already knew that microorganisms, especially the anaerobic bacteria in these donations, can survive these conditions," Lee said. "So it wasn't a surprise."
Indeed, many sources of FMT donor material already operate this way, even though this is the first randomised control study to directly compare fresh and frozen treatments – so it's reassuring to see confirmation that freezing doesn't hurt the helpful microbes. Lee hopes to examine dehydration next, since this could make samples last even longer.
Lee and her colleagues administered one or two FMT enemas to 178 patients, splitting them into two groups to compare freshly-harvested samples and ones that had been frozen and defrosted.
Thirteen weeks later, 85 per cent of the fresh patients were diarrhoea-free.
In the frozen group, the success rate reached 83.5 per cent – a margin that allows Lee and her team to dub the treatment "non-inferior".
Another 219 patients had to have their treatment altered in some way – receiving antibiotics or getting their FMT from more than one donor, for example – but the frozen and fresh success rates still held tight at 70 and 75 per cent, respectively.
- The Washington Post