Testing Oxalobacter formigenes Colonization to Reduce Urinary Oxalate in Adults with Calcium Oxalate Kidney Stones

What this Trial Is About

Researchers are investigating whether colonization with the gut bacteria Oxalobacter formigenes can reduce urinary oxalate levels in adults with a history of calcium oxalate kidney stones who are not currently colonized with this bacteria. The study aims to better understand how this bacterial colonization affects oxalate excretion and kidney stone formation. Participants will follow fixed diets with controlled amounts of oxalate to assess these effects. The study includes several phases screening and pre-colonization, colonization and post-colonization, and a follow-up phase. During pre-colonization, participants consume low and moderately high oxalate diets for 4 days each, collecting urine, blood, and stool samples. After that, they ingest a live preparation of Oxalobacter formigenes to induce colonization, which is confirmed by stool testing. Post-colonization, participants repeat the same diet and sample collection process. Follow-up visits occur every 6 months for up to 4 years to monitor colonization sustainability and collect additional samples. Throughout the study, participants provide multiple 24-hour urine collections, blood samples, and stool samples to measure urinary oxalate and confirm bacterial colonization. Researchers will evaluate changes in urinary oxalate excretion two months after colonization and the long-term maintenance of colonization over four years. Participants are also monitored for diet adherence and complete questionnaires during follow-up visits. The total study duration includes initial diet phases, colonization, and several years of follow-up assessments.

O. Formigenes Colonization in Calcium Oxalate Kidney Stone Disease