Fecal Transplantation for Recurrent Clostridium difficile Infection in Older Adults: A Review - https://onlinelibrary.wiley.com/doi/abs/10.1111/jgs.12378

Fecal Microbiota Transplantation for Clostridium difficile Infection: A Systematic Review - https://annals.org/aim/article-abstract/2288521/fecal-microb...

I just cribbed these from the Wikipedia article at https://en.wikipedia.org/wiki/Clostridioides_difficile_infec... so I don't know if there's better or more recent studies.