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These are very small, Gram negative bacteria. They belong to the Proteobacteria group and are about 1/20 the size of most of their larger cousins in this group. They may play a pathogenic role in kidney stones and atherosclerosis. These bacteria are unique by developing a needle-shaped calcium apatite cell wall, forming an enclosure around the organism.


Nanobacteria and calcinosis cutis.

Morgan MB.

Department of Pathology, James Haley Veteran's Hospital, and University of South Florida College of Medicine, Tampa, FL, USA.

J Cutan Pathol 2002 Mar;29(3):173-5 Abstract quote

BACKGROUND: The nanobacteria are a recently characterized group of extremely small bacteria capable of precipitating calcium salts implicated in the pathogenesis of urinary calculi and calcific atherosclerosis. The pathogenesis of calcinosis cutis and its significance in conjunction with a variety of unrelated scarring and pre-existing cutaneous entities are incompletely understood.

METHODS: A series of cases, including basal cell carcinoma with dystrophic calcification, subepidermal calcified nodule, pilomatricoma, and tumoral calcinosis, were ultrastructurally examined for the presence of Nanobacteria sp.

RESULTS: All cases, including three basal cell carcinomas, two subepidermal calcified nodules, three cases of pilomatricoma, and two cases of tumoral calcinosis, were negative for Nanobacteria.

CONCLUSIONS: The dystrophic calcification that occurs in conjunction with the above entities does not likely involve a bacterial-induced etiology. The cause of these entities remains unknown.


Nanobacteria: an alternative mechanism for pathogenic intra- and extracellular calcification and stone formation.

Kajander EO, Ciftcioglu N.

Department of Biochemistry and Biotechnology, University of Kuopio, P.O.B. 1627, Fin-70211, Kuopio, Finland.

Proc Natl Acad Sci U S A 1998 Jul 7;95(14):8274-9 Abstract quote

Calcium phosphate is deposited in many diseases, but formation mechanisms remain speculative. Nanobacteria are the smallest cell-walled bacteria, only recently discovered in human and cow blood and commercial cell culture serum.

In this study, we identified with energy-dispersive x-ray microanalysis and chemical analysis that all growth phases of nanobacteria produce biogenic apatite on their cell envelope. Fourier transform IR spectroscopy revealed the mineral as carbonate apatite. The biomineralization in cell culture media resulted in biofilms and mineral aggregates closely resembling those found in tissue calcification and kidney stones. In nanobacteria-infected fibroblasts, electron microscopy revealed intra- and extracellular acicular crystal deposits, stainable with von Kossa staining and resembling calcospherules found in pathological calcification. Previous models for stone formation have led to an hypothesis that elevated pH due to urease and/or alkaline phosphatase activity is a lithogenic factor. Our results indicate that carbonate apatite can be formed without these factors at pH 7.4, at physiological phosphate and calcium concentrations.

Nanobacteria can produce apatite in media mimicking tissue fluids and glomerular filtrate and provide a unique model for in vitro studies on calcification.

Nanobacteria: an infectious cause for kidney stone formation.

Ciftcioglu N, Bjorklund M, Kuorikoski K, Bergstrom K, Kajander EO.

Department of Biochemistry, University of Kuopio, Finland.

Kidney Int 1999 Nov;56(5):1893-8 Abstract quote

BACKGROUND: Nanobacteria are cytotoxic, sterile-filterable, gram-negative, atypical bacteria detected in bovine and human blood. Nanobacteria produce carbonate apatite on their cell walls. Data on Randall's plaques suggest that apatite may initiate kidney stone formation. We assessed nanobacteria in 72 consecutively collected kidney stones from Finnish patients.

METHODS: Nanobacteria and kidney stone units were compared using scanning electron microscopy (SEM). Demineralized kidney stones were screened for nanobacteria using a double-staining method and a specific culture method. Isolated nanobacteria were analyzed for mineral formation in vitro with Ca and 85Sr incorporation tests.

RESULTS: SEM highlighted the resemblance in size and morphology of nanobacteria and the smallest apatite units in the kidney stones. Nanobacterial antigens could be detected after the demineralization of the stones in 1 N HCl. Nanobacteria were surprisingly resistant to this treatment, and cultures could be established from 93.1% of the stones. Only struvite stones had common bacteria, in addition to the nanobacteria. When the results of all of the assays were combined, 70 of the 72 stones (that is, 97.2%) were nanobacteria positive. Although apatite stones indicated highest nanobacteria antigen signals, the overall nanobacteria positivity did not depend on the stone type. The isolated nanobacteria produced apatite stones in vitro, measured by Ca and 85Sr incorporation.

CONCLUSIONS: We propose that kidney stone formation is a nanobacterial disease analogous to Helicobacter pylori infection and peptic ulcer disease. Both diseases are initiated by bacterial infection and subsequently endogenous and dietary factors influence their progression.

An alternative interpretation of nanobacteria-induced biomineralization.

Cisar JO, Xu DQ, Thompson J, Swaim W, Hu L, Kopecko DJ.

Oral Infection and Immunity Branch, and Cellular Imaging Core, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, 20892, USA.

Proc Natl Acad Sci U S A 2000 Oct 10;97(21):11511-5 Abstract quote

The reported isolation of nanobacteria from human kidney stones raises the intriguing possibility that these microorganisms are etiological agents of pathological extraskeletal calcification [Kajander, E. O. & Ciftcioglu, N. (1998) Proc. Natl. Acad. Sci. USA 95, 8274-8279]. Nanobacteria were previously isolated from FBS after prolonged incubation in DMEM. These bacteria initiated biomineralization of the culture medium and were identified in calcified particles and biofilms by nucleic acid stains, 16S rDNA sequencing, electron microscopy, and the demonstration of a transferable biomineralization activity.

We have now identified putative nanobacteria, not only from FBS, but also from human saliva and dental plaque after the incubation of 0.45-microm membrane-filtered samples in DMEM. Although biomineralization in our "cultures" was transferable to fresh DMEM, molecular examination of decalcified biofilms failed to detect nucleic acid or protein that would be expected from growth of a living entity. In addition, biomineralization was not inhibited by sodium azide. Furthermore, the 16S rDNA sequences previously ascribed to Nanobacterium sanguineum and Nanobacterium sp. were found to be indistinguishable from those of an environmental microorganism, Phyllobacterium mysinacearum, that has been previously detected as a contaminant in PCR.

Thus, these data do not provide plausible support for the existence of a previously undiscovered bacterial genus. Instead, we provide evidence that biomineralization previously attributed to nanobacteria may be initiated by nonliving macromolecules and transferred on "subculture" by self-propagating microcrystalline apatite.

Nanobacteria: controversial pathogens in nephrolithiasis and polycystic kidney disease.

Kajander EO, Ciftcioglu N, Miller-Hjelle MA, Hjelle JT.

Department of Biochemistry, University of Kuopio, Kuopio, Finland.

Curr Opin Nephrol Hypertens 2001 May;10(3):445-52 Abstract quote

Nanobacteria are unconventional agents 100-fold smaller than common bacteria that can replicate apatite-forming units. Nanobacteria are powerful mediators of biogenic apatite nucleation (crystal form of calcium phosphate) and crystal growth under conditions simulating blood and urine. Apatite is found in the central nidus of most kidney stones and in mineral plaques (Randall's plaques) in renal papilla.

The direct injection of nanobacteria into rat kidneys resulted in stone formation in the nanobacteria-injected kidney during one month follow-up, but not in the control kidney injected with vehicle. After intravenous administration in rats and rabbits, nanobacteria are rapidly excreted from the blood into the urine, as a major elimination route, and damage renal collecting tubuli. Nanobacteria are cytotoxic to fibroblasts in vitro. Human kidney cyst fluids contain nanobacteria. Nanobacteria thus appear to be potential provocateurs and initiators of kidney stones, tubular damage, and kidney cyst formation.

It is hypothesized that nanobacteria are the initial nidi on which kidney stone is built up, at a rate dependent on the supersaturation status of the urine. Those individuals having both nanobacteria and diminished defences against stone formation (i.e. genetic factors, diet and drinking habits) could be at high risk. Kidney cyst formation is hypothesized to involve nanobacteria-induced tubular damage and defective tissue regeneration yielding cyst formation, the extent of which is dependent on genetic vulnerability.

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