It’s long been thought that only an unusual type of kidney stone has any connection to bacteria, and that the vast majority of kidney stones, which are caused by calcium oxalate crystals, don’t host any bacteria. But new research has upended that assumption. Reporting in the Proceedings of the National Academy of Sciences (PNAS), researchers have determined that bacteria can be found in calcium oxalate stones after all. These findings, which significantly broaden our understanding of kidney stones, may eventually open up better options for preventing or treating painful kidney stones.
“This breakthrough challenges the long‑held assumption that these stones develop solely through chemical and physical processes, and instead shows that bacteria can reside inside stones and may actively contribute to their formation,” said co-corresponding study author Dr. Kymora Scotland, an assistant professor of urology at UCLA. “By uncovering this novel mechanism, the study opens the door to new therapeutic strategies that target the microbial environment of kidney stones.”
The buildup of small crystals in urine can lead to kidney stones, and they are getting more common. It’s been estimated that about one in eleven people will eventually get kidney stones. Several factors are thought to influence the likelihood of kidney stones, like low fluid intake, family history, or metabolic syndrome, which can be any combination of high blood pressure, high blood sugar, high cholesterol, or excessive belly fat. As crystals accumulate in urine, they may become too large to excrete with normal urine flow, and kidney stones can form.
In this study, the researchers found not only bacterial cells but also layers of bacterial biofilms when examining electron and florescence microscopy data from calcium oxalate kidney stones. There was bacteria throughout the crystals. Bacteria could also be related to other types of kidney stones as well.
“We found a new mechanism of stone formation that may help to explain why these stones are so common,” Scotland said. “These results may also help to explain the connections between recurrent urinary tract infections and recurrent kidney stone formation, and provides insights on potential future treatment for these conditions.”
Now, the researchers want to learn more about how bacteria may be involved in the formation of other kidney stone types, and to learn exactly how the bacteria interact with them.
Sources: University of California, Los Angeles; Proceedings of the National Academy of Sciences (PNAS)