Does the intestinal microbiome play a role in kidney stone risk?
Of the numerous organisms comprising the intestinal microbiome, oxalate-degrading bacteria, particularly Oxalobacter formigenes , are the most interesting in relation to stone disease. O. formigenes is an anaerobic bacterium that is a common component of colonic flora; O. formigenes metabolizes oxalate and presumably lowers the amount of oxalate available for intestinal absorption.
It appears O. formigenes can stimulate colonic secretion of oxalate, which should reduce urine oxalate as well.
Some observational studies have found lower rates of O. formigenes colonization in patients with kidney stones, suggesting a role in stone formation.
Though animal models of hyperoxaluria have shown reduced urinary oxalate excretion when treated with O. formigenes , there are no controlled trials demonstrating a convincing effect in humans to date.