Scientists have found evidence for the first time of bacteria hiding in “non-infectious” kidney stones.
These hardened clumps of small crystals are made from chemicals in urine and are thought to form due to a lack of fluid or high concentrations of minerals and chemicals.
Most kidney stones are considered non-infectious after passing. But that may not be the case.
A study led by UCLA researchers has now found that calcium oxalate kidney stones, the most common type, are rich in bacteria.
In fact, these stones contain bacterial flakes as part of their intrinsic internal structure.
“This breakthrough challenges the long-held assumption that these stones form solely through chemical and physical processes, and instead shows that bacteria can reside inside the stones and may actively contribute to their formation,” explains UCLA urologist Kymora Scotland.
“By revealing this new mechanism, this study opens the door to new therapeutic strategies that target the microbial environment of kidney stones.”
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The findings suggest that in some cases where kidney stones keep coming back, there may be a bacterial infection in the kidneys, ureters or bladder that causes the recurrence.
If this infection is treated, there may be fewer kidney stones in the future.
Using electron and fluorescence microscopy, the researchers found structural and chemical evidence of bacteria in calcium oxalate stones taken from human patients.
This was true even among participants who did not have an underlying urinary tract infection.
“We have discovered a new stone-forming mechanism that may help explain why these stones are so common,” Scotland said.
“These results may also help explain the link between recurrent urinary tract infections and recurrent kidney stone formation and provide insights into potential future treatments for these diseases.”
Related: These 7 common daily habits may be damaging your kidneys
As many as 1 in 10 people will develop kidney stones in their lifetime, with more than 70% of cases being caused by calcium oxalate stones.
If bacteria play an important role in their formation, treatment and guidance for kidney stones may need to be updated.
The study was published in Proceedings of the National Academy of Sciences.
