Most kidney stones are considered noninfectious after they are passed<\/a>. But that may not be true after all.<\/p>\n A study led by researchers at the University of California Los Angeles (UCLA) has now found that calcium oxalate kidney stones, the most common type, are enriched with bacteria.<\/p>\n In fact, these stones contain sheets of bacteria as part of their intrinsic internal structure.<\/p>\n “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,” explains<\/a> urologist Kymora Scotland from UCLA.<\/p>\n “By uncovering this novel mechanism, the study opens the door to new therapeutic strategies that target the microbial environment of kidney stones.”<\/p>\n The findings suggest that in some cases where kidney stones keep coming back, there may be a bacterial infection in the kidney, ureter, or bladder contributing to recurrence.<\/p>\n If this infection is treated, then perhaps there may be fewer kidney stones going forward.<\/p>\n Using electron and fluorescence microscopy, the researchers found structural and chemical evidence of bacteria in calcium oxalate stones taken from human patients.<\/p>\n This was true even among participants without underlying urinary tract infections.<\/p>\n “We found a new mechanism of stone formation that may help to explain why these stones are so common,” says<\/a> Scotland.<\/p>\n “These results may also help to explain the connections between recurrent urinary tract infections and recurrent kidney stone formation, and provide insights on potential future treatment for these conditions.”<\/p>\n![\"Subscribe](\"https:\/\/www.europesays.com\/us\/wp-content\/uploads\/2026\/02\/Octopus-yellow-final-642x272.jpg\")
<\/a><\/p>\n![\"Bacterial](\"https:\/\/www.europesays.com\/us\/wp-content\/uploads\/2026\/02\/pnas.2517066123fig03-642x321.jpg\")
Bacterial-biofilm components (false-colored yellow) identified within kidney stones. (Schmidt et al., PNAS<\/a>, 2026)<\/p>\n