Oxalobacter formigenes
Oxalobacter formigenes is an oxalate-degrading anaerobic bacterium that colonizes the large intestines of numerous vertebrates, including humans. O. formigenes and humans share a beneficial symbiosis.
Quinolone, a broad-spectrum antibiotic, kills O. formigenes. If a person's gastrointestinal (GI) tract lacks this bacterium, and therefore lacks the primary source for the oxalyl-CoA decarboxylase enzyme, then the GI tract cannot degrade dietary oxalates which on digestion get absorbed easily and after some vitamin B6-modulated partial metabolical degradation in the body, is excreted in the kidney, where it precipitates with calcium to form calcium oxalate kidney stones.