Bacteria Inside Kidney Stones Rewrite How Stones Form

A UCLA-led study finds calcium oxalate kidney stones harbor bacteria and even internal biofilm, suggesting microbes may contribute to stone formation rather than stones forming purely by chemistry. This challenges the view that stones are noninfectious and implies infections in the kidney, ureter, or bladder could drive recurrence; targeting the microbial environment may reduce future stones. Findings come from electron and fluorescence microscopy of human stones and were published in PNAS (2026).