Photo: Illustrative image of a rod-shaped bacterium / Getty Images
Researchers in the United States have discovered living bacteria and biofilms inside kidney stones made of calcium oxalate. This is the most common type of kidney stone, accounting for about 80% of cases. Until now, scientists believed these stones were formed purely from minerals crystallized from salts in urine, reports Science Alert.
However, the new study shows that bacteria are not only present in these stones but may also contribute to their formation.
According to urologist Kimora Scotland from University of California, Los Angeles, the discovery challenges a long-standing assumption that such stones arise solely from chemical and physical processes. Instead, bacteria can live inside the stones and actively participate in their development. Identifying this mechanism could open the door to new treatment strategies targeting the microbial environment within kidney stones.
Kidney stones cause severe pain. While treatable, they can lead to serious complications without proper medical care.
Scientists already knew bacteria were involved in forming struvite kidney stones, a relatively rare type that accounts for about 2–6% of cases. But the presence of bacteria in calcium-based stones—the type affecting most patients—had not been demonstrated before.
Using electron and fluorescent microscopy, the research team found not just a few bacteria attached to the surface of the stones. They identified living bacteria and even biofilms embedded inside the crystals that make up the stones.
According to Scotland, the findings reveal a previously unknown mechanism of stone formation. The results may also help explain why recurrent urinary tract infections are often linked to repeated kidney stone formation and could guide future treatments for these conditions.
