Hoppe B et al. (2006) Oxalobacter formigenes: a potential tool for the treatment of primary hyperoxaluria type 1. Kidney Int 70: 1305–1311

Type 1 primary hyperoxaluria is a genetic disease caused by deficiency or absence of liver-specific alanine:glyoxylate aminotransferase, which leads to overproduction of endogenous oxalate. The disease is characterized by renal calculi, nephrocalcinosis and declining renal function, but treatment options are scarce. A recent study showed that Oxalobacter formigenes, a bacterium often present in the gut that is capable of degrading oxalic acid, might be able to degrade endogenously produced oxalate, thus lowering urinary oxalate excretion in patients with primary hyperoxaluria.

Two formulations of O. formigenes administered twice a day were tested. A frozen paste containing live cells was tested in five patients with normal renal function, three patients with end-stage renal disease (ESRD) and one patient who had undergone a liver–kidney transplant (IxOC-2 study); enteric-coated capsules containing freeze-dried live cells were tested in six patients with normal or stable renal function and one patient who had undergone a liver–kidney transplant (IxOC-3 study). Twenty-four-hour urine samples (or plasma samples in patients with ESRD) were analyzed weekly over 4 weeks of treatment. Patients achieving a decrease in their urinary oxalate excretion of >20% at weeks 3 and 4 were classified as responders.

In the IxOC-2 study, three of the five patients with normal renal function responded to treatment, and plasma oxalate levels decreased in two of the three patients with ESRD. In the IxOC-3 study, four of the six patients with normal or stable renal function responded to treatment. The bacteria colonized the gut only transiently and no major adverse effects were reported.