Rapid reversal of hyperoxaluria in a rat model after probiotic administration of Oxalobacter formigenes

Purpose: The gut inhabiting bacterium Oxalobacter formigenes may be a negative risk factor in recurrent calcium oxalate kidney stone disease that apparently maintains oxalic acid homeostasis in its host via the degradation of dietary oxalate. The possibility of using this bacterium as probiotic treatment to reduce urinary oxalate was investigated in a rat model. Materials and Methods: Male Sprague-Dawley rats were placed on a diet supplemented with ammonium oxalate to induce a state of severe hyperoxaluria. Subgroups of these rats received an esophageal gavage of 1 X 10(3), 10(5), 10(7) or 10(9) O. formigenes per feeding for a 2-week period. Each rat was followed for general health and changes in urinary oxalate. Results: Rats with chronic hyperoxaluria resulting from high dietary oxalate that were treated with O. formigenes showed decreased urinary oxalate within 2 days of initiating probiotic supplementation. The amount of the decrease in a 2-week period proved directly proportional to the dose of bacteria. Urinary oxalate in rats receiving higher amounts of O. formigenes returned to almost normal. Throughout the study the rats remained healthy with no signs of toxicity, antibody development or a histopathological condition. Conclusions: Probiotic treatment of hyperoxaluric rats with O. formigenes may significantly and rapidly reduce the level of oxalate in the urine. This probiotic treatment appears to be safe and well tolerated. The approach may be feasible for treating calcium oxalate kidney stone disease.