When a stone is too big to pass naturally, it can cause chronic urinary tract and kidney infections, such as pyelonephritis. Kidney stones can act as a focus for organisms to live, and organisms provide the focus around which stones can grow, so the problem of infection can become self perpetuating.
Last year, a new type of bacteria called nanobacteria was discovered in both human and cow blood. Related to the Brucella and Bartonella species, the bacteria is the smallest known strain with a cell wall. Scientists discovered that these novel bacteria can produce, in culture, a structure that precipitates carbonate apatite crystals, similar to those found in the core of many kidney stones.
When the Finnish team that discovered the nanobacteria examined 30 randomly collected kidney stones, it found them thriving in each and every one of the stones. Their results were confirmed when cultured extracts of all 30 stones grew the nanobacteria (Proc Natl Acad Sci, 1998; 95: 8274-9). Bacterial infection has long been associated with kidney stones. However, this study suggests that at least some kidney stones might be caused by infection a conclusion which opens up new possibilities for treatment and prevention.