Role of bacteria in the development of kidney stones.

Currently, only struvite stones are regarded as deriving from bacteria. Recent work has suggested that calcium-based stones might also have an infectious origin. Nanobacteria, small intracellular bacteria found in human kidney stones, are capable of forming a calcium phosphate shell, and thus could serve as crystallization centres for renal calculi formation. Until now, however, all trials performed to confirm the presence of nanobacteria in human calculi, serum or urine have failed. In a hyperoxaluric rat model, tissue-residing macrophages were able to remove interstitial crystals and thus may not be primarily engaged in defending against micro-organisms, if present.