title: The role of Oxalobacter formigenes colonization in calcium oxalate stone disease.
abstract: About 75% of urinary stones contain oxalate. As Oxalobacter formigenes is a Gram-negative anaerobic bacterium that degrades oxalate in the intestinal tract, we assessed the role of O. formigenes in oxalate metabolism by evaluating its intestinal absorption, plasma concentration, and urinary excretion. Of 37 calcium oxalate stone formers, 26 tested negative for O. formigenes and were compared with the 11 patients who tested positive. Patients provided 24-h urine samples on both a self-selected and a standardized diet. Urinary oxalate excretion did not differ significantly on the self-selected diet, but was significantly lower in O. formigenes-positive than in O. formigenes-negative patients under controlled, standardized conditions. Intestinal oxalate absorption, measured using [(13)C₂]oxalate, was similar in the patients with or without O. formigenes. Plasma oxalate concentrations were significantly higher in noncolonized (5.79 μmol/l) than in colonized stone formers (1.70 μmol/l). Colonization with O. formigenes was significantly inversely associated with the number of stone episodes. Our findings suggest that O. formigenes lowers the intestinal concentration of oxalate available for absorption at constant rates, resulting in decreased urinary oxalate excretion. Thus, dietary factors have an important role in urinary oxalate excretion. The data indicate that O. formigenes colonization may reduce the risk of stone recurrence.
authors.affiliation: University Stone Centre, Department of Urology, University of Bonn, Bonn, Germany. Roswitha.Siener@ukb.uni-bonn.de
authors.forename: Roswitha
authors.initials: R
authors.lastname: Siener
authors.forename: Ursula
authors.initials: U
authors.lastname: Bangen
authors.forename: Harmeet
authors.initials: H
authors.lastname: Sidhu
authors.forename: Ruth
authors.initials: R
authors.lastname: Hönow
authors.forename: Gerd
authors.initials: G
authors.lastname: von Unruh
authors.forename: Albrecht
authors.initials: A
authors.lastname: Hesse
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood / Q000652:urine; D002129:Calcium Oxalate / Q000097:blood / Q000378:metabolism* / Q000652:urine; D004032:Diet; D005260:Female; D006801:Humans; D007408:Intestinal Absorption; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000382:microbiology*; D008297:Male; D008875:Middle Aged; D020624:Oxalobacter formigenes / Q000254:growth & development / Q000378:metabolism*; D055502:Secondary Prevention; D014545:Urinary Calculi / Q000378:metabolism / Q000382:microbiology* / Q000517:prevention & control; D055815:Young Adult
chemical_list: D015415:Biomarkers; D002129:Calcium Oxalate