Thank you for reaching out to the Connect community with such an insightful observation!
Although research regarding FMT is still ongoing, there are a number of published studies which explore the role of gut bacteria in stone pathophysiology. Here are a few you may wish to read:
– Manipulating the gut microbiota to maintain health and treat disease https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4315778/
"Oxalobacter formigenes is the key bacterium responsible for the degradation of oxalate in humans, and an accumulation of oxalate is the main case of kidney stone formation. Patients suffering from calcium oxalate kidney stones are less likely to be colonized by O. formigenes. The bacterium is sensitive to many commonly used antibiotics and is less abundant in individuals who have undergone antibiotic treatment at some point in their life. Oral recolonisation with Oxalobacter has been successful (52), although it is not permanent. Identification of specific substrates to boost existing numbers of O. formigenes would be a viable alternative therapy, but the preliminary microbiology work has yet to be done."