Nanobacteria-caused mitral valve calciphylaxis in a man with diabetic renal failure.

We have found that nanobacteria, recently discovered Gram-negative atypical bacteria, can cause local calciphylaxis on the mitral valve in a setting of high-calcium X phosphorous product in the blood. We present the case of a 33-year-old man with diabetic renal failure on continuous ambulatory peritoneal dialysis who died as a result of multiple brain infarcts due to embolizations from mitral valve vegetations. Systemic calciphylaxis was not present. Spectrometric analysis of the mitral valve vegetations showed that they were composed of calcium phosphate, carbonate apatite form, and fibrin. The electron microscopy of the thrombotic vegetation demonstrated nanobacterium as a nidus for carbonate apatite formation. Investigation for the presence of nanobacteria in the multiple organs involved in systemic calciphylaxis may be of help in elucidating the pathogenesis of this frequently fatal disorder.