With New Gene-Probing Test, UF Scientists Seek Means Of Preventing Kidney Stones

October 2, 1996

GAINESVILLE–A newly developed laboratory test accurately detects an intestinal bacteria believed to help prevent the most common type of kidney stone, University of Florida researchers report today.

UF researchers are now applying the test in clinical studies to confirm a strongly suspected link between the absence of the intestinal bacteria Oxalobacter and so-called calcium oxalate kidney stones.

Dr. Ammon Peck, an immunologist with UF’s College of Medicine whose genetic discoveries paved the way for developing the diagnostic test, is optimistic that if this link is verified, then calcium oxalate kidney stones may be prevented by replenishing a patient’s supply of the “good bacteria.”

Biochemist Harmeet Sidhu of Chandigarh, India, who developed the test under Peck’s direction, described the test today at the 8th International Symposium on Urolithiasis, in Dallas. Sidhu is a visiting scientist at UF.

Implications of the Florida study are far-reaching, since 5 to 10 percent of the general population are affected by calcium oxalate kidney stones, and close to 1 million Americans suffer from kidney stones every year. This disease is especially prevalent in 30- to 39-year-old men. More than $1 billion is spent in this country every year in treating kidney stones, which may involve surgery or the use of repetitive high-energy shock waves aimed at the stones until they disintegrate.

UF researchers are collaborating with microbiologist Milton Allison of Iowa State University, who first identified Oxalobacter as an organism essential to the body’s ability to break down oxalate, a toxic byproduct of digestion. During the early 1980s, Allison verified the role of Oxalobacter in degrading harmful oxalate (also known as oxalic acid) in the body before it has a chance to bind with calcium to form crystals that turn into kidney stones.

Peck subsequently discovered two genes within Oxalobacter that play key roles in breaking down oxalate. He now has U.S. patents pending on both the genes and on their use in the new diagnostic test.

In current UF studies, Peck and colleagues are incorporating the gene-probing test in large-scale, controlled clinical studies to further define the link between the absence of Oxalobacter and kidney stone development. The test will, within two days, precisely identify the strains of bacteria known to block kidney stone formation. The test incorporates the Oxalobacter genes and uses them to seek out and bind to the same genes (if present) in DNA extracted from stool samples.

Why some people lack the vital intestinal bacteria is not understood. However, some preliminary observations have indicated that certain medications, including antibiotics and protease inhibitors (prescribed for AIDS therapy), can destroy the organism.

Results of the Florida research are expected to have applications not only for the prevention of oxalate kidney stones, but also for other diseases related to an overabundance of oxalic acid in the body. Excess amounts of this naturally occurring organic compound have corrosive effects on the body. Oxalate overabundance has been linked to certain heart problems including abnormal conduction of electrical signals in the heart as well as kidney failure and, in some cases, death.

Recently, Peck and colleagues discovered — through testing 100 healthy children in the Ukraine — that colonies of Oxalobacter were established in all of the youngsters by age 5. However, at about 8 years of age, the number of children still colonized with the bacteria had decreased and by the age of 11 or 12, only about 70 percent of the children still tested positive for the bacteria.

To determine the extent to which medications may reduce or destroy colonies of Oxalobacter in children, pediatrics Professor Dr. Richard Neiberger is now collecting stool samples from patients, ranging in age from newborn to 12 years, in the Shands Children’s Hospital at UF. Analysis of these samples, using the test for Oxalobacter, will be compared with those of the Ukrainian study.

The studies are supported in part by Ixion Biotechnology Inc., located in the Sid Martin Biotechnology Development Institute at UF’s Progress Center in Alachua. All three participants in the UF study own shares in Ixion, which also owns licensing rights to the Oxalobacter gene technology.