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.
"One of the major challenges to maintaining FMT is donor availability," Lee told The Post. FMT donors must have a perfectly healthy gut microbiome, lest their donation infect an ill patient with even more harmful bacteria. In fact, one donation center has a lower acceptance rate than nearby Ivy League schools. 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 randomized 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 percent of the fresh patients were diarrhea-free. In the frozen group, the success rate reached 83.5 percent – a margin that allows Lee and her team to dub the treatment "noninferior." 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 percent, respectively.
The researchers involved in the new study are already working on getting FDA approval for the treatment of ulcerative colitis, and other groups are testing FMT for things as wild as treating obesity. So even if you're never infected with C. difficile, cheaper and more readily available FMT donations may come in handy for you one day.