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 80 Years. Per ClinicalTrials.gov, last updated 2026-10-13.
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.
509 studies on the registry are indexed under Kidney Calculi; 146 are open to participants now.
This study's planned enrollment of 40 is below the median of 86 across 391 interventional studies indexed under Kidney Calculi.
Browse Kidney Calculi studies →University of Alabama at Birmingham is the lead sponsor of 1,421 studies on the registry; 277 are open to participants now.
Of its 164 completed or terminated interventional studies of FDA-regulated products, 130 (79%) have results posted.
Counted across the registry records on this site, refreshed daily.
The criteria were revised on the registry on Oct 13, 2026. See what changed
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer (malignancy)
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Immunosuppression
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
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.
Started Apr 2024 (actual). Primary completion is estimated for Dec 2030, 80 months after the start.
Of 183 non-industry interventional studies with no phase under Kidney Calculi, half reached primary completion within 31 months of starting (the median), counting those still running; a quarter within 13 and three quarters within 54. This study's planned 80 months is above that.
Counting every sponsor, half of 199 studies reached it within 26 months; a quarter within 12 and three quarters within 51.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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University of Alabama at Birmingham →