Health Capsule

Scientists have discovered that bacteria likely play an important role in the formation of most kidney stones. Earlier research had only connected bacteria to stones that developed after an infection.

Kidney stones are small, rock-like deposits that develop in the kidneys. They form when minerals in urine crystallize and stick together. The majority are composed of calcium oxalate. Other stones arise following urinary tract infections (UTIs). These are known as struvite stones and are associated with bacteria responsible for UTIs.

In the study, researchers examined kidney stones that had been surgically removed. Using advanced, high-powered microscopes, they analyzed both calcium oxalate and struvite stones in detail.

The investigators detected bacteria in stones taken from individuals both with and without a history of UTIs. Inside the stones, the bacteria were arranged in biofilms—clusters of microorganisms that adhere to one another and to surfaces. These biofilms appeared to produce substances that encourage minerals to gather and solidify into stones.

Scientists are continuing to explore how bacteria contribute to kidney stone development. A clearer understanding of this relationship may open the door to new strategies for preventing stones or improving treatment options.

“This discovery challenges the long-standing belief that kidney stones form purely through chemical and physical reactions,” says Dr. Kymora Scotland of the University of California, Los Angeles. “Our findings suggest that bacteria can live within the stones themselves and may actively influence how they develop.”