Fecal microbiota transplants have sometimes resulted in negative outcomes, even with donors from indigenous populations or recipients with autism, suggesting potential host ecosystem mismatch.

“I've actually seen this in you know some of I've had several patients do fecal microbiota transplants either you know through the team out clinic in in the UK or a couple of other places that I'm aware of that I'm not at liberty to speak of publicly one place very interestingly was using the microbiota from somewhat indigenous population and I saw instances where that didn't go well and it you know it didn't seem to be because a pathogen was was you know was passed it was just like a mismatch between the host ecosystem and the microbiome from that completely different population I've heard of anecdotes like this Amazonian microbiota being translated transplanted into kids with autism and having them get worse”