O. Formigenes Colonization in Calcium Oxalate Kidney Stone Disease

Last updated: May 9, 2025
Sponsor: University of Alabama at Birmingham
Overall Status: Active - Recruiting

Phase

N/A

Condition

Kidney Stones

Treatment

Moderately high oxalate fixed diets post-colonization

Low oxalate fixed diets post-colonization

Colonization with Oxalobacter formigenes

Clinical Study ID

NCT06330246
IRB300005280-OCK
R01DK137784
  • Ages 18-70
  • All Genders

Study Summary

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

  • ingest fixed diets containing low and moderately high amounts of oxalate for 4 days at a time

  • collect urine, blood and stool samples during the fixed diets

  • ingest a preparation of live Oxalobacter formigenes to induce colonization with Oxalobacter formigenes

Eligibility Criteria

Inclusion

Inclusion Criteria

  • age 19-70 yrs

  • Body Mass Index > 18.5 kg/m2

  • First time or recurrent Calcium Oxalate stone former. Composition of most recent stone ≥ 50% calcium oxalate if available

  • Not colonized with Oxalobacter formigenes

  • Normal fasting serum electrolytes on comprehensive metabolic profile

  • Willing to ingest fixed diets

  • Willing to stop supplements (vitamins including vitamin C, calcium (citrate or carbonate) and other minerals, herbal supplements, nutritional aids, probiotics) for 2 weeks before start and during fixed diet phases.

  • If on medications for stone prevention (e.g. thiazides, citrate, allopurinol), stable dose regimen for at least 2 weeks prior to and during study

Exclusion Criteria

  • Chronic Kidney Disease stage 4-5

  • Primary hyperoxaluria

  • Liver, endocrine or renal diseases (other than idiopathic Calcium Oxalate kidney stones) or any other condition that may influence the absorption, transport or urinary excretion of ions, which will compromise the interpretation of results, including: Cystic fibrosis, Cystinuria, Uric acid stone former, Nephrotic syndrome, Sarcoidosis, Renal tubular acidosis, Primary hyperparathyroidism, Neurogenic bladder, Urinary diversion

  • Pregnancy or breast-feeding

  • Incompatible dietary requirements with the study, food allergies or intolerance to any of the foods in study menus

  • Active malignancy or treatment for malignancy within 12 months prior to screening

  • Utilization of immunosuppressive medication

  • Uncontrolled Hypertension or diabetes

  • Diabetes type 1

  • Current Colonization with Oxalobacter formigenes

Study Design

Total Participants: 40
Treatment Group(s): 5
Primary Treatment: Moderately high oxalate fixed diets post-colonization
Phase:
Study Start date:
April 17, 2024
Estimated Completion Date:
December 31, 2031

Study Description

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.

Connect with a study center

  • University of Alabama at Birmingham

    Birmingham, Alabama 35294
    United States

    Active - Recruiting

  • UTSW

    Dallas, Texas 75390
    United States

    Active - Recruiting

Not the study for you?

Let us help you find the best match. Sign up as a volunteer and receive email notifications when clinical trials are posted in the medical category of interest to you.