An interventional study of Low oxalate fixed diets pre-colonization and Moderately high oxalate fixed diets pre-colonization in Kidney Stone, Kidney Calculi and Urolithiasis, sponsored by University of Alabama at Birmingham. Recruiting at 2 sites in United States. Open to participants aged 18 Years to 70 Years. Per ClinicalTrials.gov, last updated 2026-08-27.
Sponsored by University of Alabama at Birmingham · Not applicable, Interventional, and Basic science
The goal of this trial is to test if colonization with the gut bacteria Oxalobacter formigenes leads to a reduction in urinary oxalate excretion in patients with calcium oxalate kidney stone disease.
The study will recruit adult participants with a history of calcium oxalate kidney stones who are not colonized with Oxalobacter formigenes.
Participants will
In this study the investigators propose to measure the excretion of urinary oxalate on a fixed diet with controlled amounts of oxalate, before and after inducing colonization with the gut bacteria Oxalobacter formigenes in individuals with a history of calcium oxalate kidney stones not already colonized with Oxalobacter formigenes.
Screening and Pre-colonization phase. Between the University of Alabama at Birmingham (UAB) and the University of Texas Southwestern Medical Center (UTSW), the study will enroll 40 individuals with a history of idiopathic calcium oxalate kidney (20 males/20 females). Screening will include stool colonization testing, blood complete metabolic profile, 24-hr urine specimens collected at home on self-selected diets and anthropometric measurements.
Participants will ingest a low-oxalate (\<60 mg/day) fixed diet for 4 consecutive days and collect two 24-hr urines and a stool sample after 2 days of dietary equilibration, as well as one fasted blood sample on the last morning.
After a wash-out period of at least 1 week, participants will ingest a moderately high-oxalate (250-300 mg/day) fixed diet for 4 consecutive days and collect two 24-hr urines and a stool sample after 2 days of dietary equilibration, as well as one fasted blood sample on the last morning.
Colonization and Post-colonization phase. Participants will be colonized with Oxalobacter formigenes by ingesting a freshly thawed paste of live bacterial preparation of O. formigenes. They will collect a stool sample 1 week later to assess if colonization occured.
After confirmation of successful colonization, participants will ingest a low-oxalate (\<60 mg/day) fixed diet for 4 consecutive days and collect two 24-hr urines and a stool sample after 2 days of dietary equilibration, as well as one fasted blood sample on the last morning.
After a wash-out period of at least 1 week, participants will ingest a moderately high-oxalate (250-300 mg/day) fixed diet for 4 consecutive days and collect two 24-hr urines and a stool sample after 2 days of dietary equilibration, as well as one fasted blood sample on the last morning.
Follow-up phase Participants will be followed up every 6 months to assess sustainability of colonization, provide a stool sample and answer a simple questionnaire. A 24-hr urine collection will be requested once a year after colonization, on the same moderately high oxalate diet diet after 2 days of dietary equilibration.
Exclusion Criteria
Colonization with a live preparation of Oxalobacter formigenes, strain OxCC13.
Dietary Supplement: Low oxalate fixed diets pre-colonization · Dietary Supplement: Moderately high oxalate fixed diets pre-colonization · Dietary Supplement: Colonization with Oxalobacter formigenes · Dietary Supplement: Low oxalate fixed diets post-colonization · Dietary Supplement: Moderately high oxalate fixed diets post-colonization
4 days of fixed eucaloric diet with low oxalate (\< 60 mg/day), normal calcium (600-1000 mg/day)
4 days of fixed eucaloric diet with moderately high oxalate (250-300 mg/day), normal calcium (600-1000 mg/day)
Ingestion of live Oxalobacter formigenes
4 days of fixed eucaloric diet with low oxalate (\< 60 mg/day), normal calcium (600-1000 mg/day)
4 days of fixed eucaloric diet with moderately high oxalate (250-300 mg/day), normal calcium (600-1000 mg/day)
Change in urinary oxalate excretion following colonization with Oxalobacter formigenes
Difference between urinary oxalate excretion on the moderately high oxalate diet pre-colonization and urinary oxalate excretion on the moderately high oxalate diet post-colonization
Time frame: 2 months
Sustainability of colonization with Oxalobacter formigenes
duration of colonization after successful induction of colonization sith Oxalobacter formigenes
Time frame: 4 years
Plan to share: No
No publications or documents are linked to this record.
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
Contact study teamGet an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
University of Alabama at Birmingham