Oxalobacter Formigenes Colonization and Urinary Oxalate Excretion

Adults that are not colonized with O. formigenes, have no history of stone disease and are in
good health as judged by their medical history, a complete metabolic profile of their serum,
and ranges of ions that influence stone formation in two 24-hour urine collections, will be
recruited from within the greater Birmingham area. Recruited subjects will be between the
ages of 18 to 65 years and with a BMI >19 and <32.

Subjects not colonized with O. formigenes will consume, firstly, a controlled diet containing
50 mg oxalate and 1000mg calcium (low oxalate/normal calcium diet), followed by a 250 mg
oxalate/400mg calcium controlled diet (moderately high oxalate/low calcium diet), with at
least a one week washout between each diet, and then repeat the same sequence of diets after
colonization with O.formigenes Group 1 strain OxCC13. Controlled diets will be prepared in
the Metabolic Kitchen of the UAB Clinical Research Unit (CRU). Each subject will perform a
sodium 13C2-oxalate oral load once at the end of each of the two dietary phases to assess
dietary oxalate absorption. Sustainability of colonization will be determined over time. Loss
of colonization will be confirmed by having the subject consume an oxalate-rich meal with
subsequent testing for O. formigenes.

Inclusion Criteria:

- Good health as judged from a medical history and reported medications

- Not colonized with O. formigenes

Exclusion Criteria:

- History of any hepatic, renal, bowel or endocrine disease or any other condition that
may influence the absorption, transport or urinary excretion of ions, which will
compromise the interpretation of results

- colonized with O. formigenes

- abnormal urine chemistries or blood metabolic profiles