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The
role of bacteria in urinary stones formation
Abstract:
Urinary
calculi occur once in a lifetime in 15% of men and 6% of
women in the world and recur in about half of these people. Stones
are known to develop because of various metabolic or environmental
factors and bacterial infections. The crystalline components of
the urinary tract stones can be classified into five types:
calcium oxalate, calcium phosphate (apatite), magnesium ammonium
phosphate (struvite), purine or cystine. Struvite and carbonate
apatite form as a consequence of a urinary tract
infection by urease-producing species of bacteria. Ammonia,
produced by the bacterial hydrolysis of urea, raises urine pH. The
alkaline pH causes the precipitation of normally soluble
polyvalent cations and anions in urine, leading to the
crystallization of struvite and carbonate apatite. Additionally,
bacteria secrete glycocalix which accelerates crystals growth and serves
to bind crystals together into a stone. Although this kind of
stones represent only 15% of all urinary stones, the
morbitidy that they cause is disproportional to the small number
of patients.However, in many cases, carbonate apatite can be
formed at neutral pH and physiological phosphate and calcium
concentrations. Recently, it was found that carbonate apatite
stones might have an infectious origin. Nanobacteria, small
intracellular bacteria found in human kidney stones, produce
carbonate apatite on their cell walls. These particles covered
with carbonate apatite could serve as crystallization centres
for renal calculi formation. This discovery could change the
diagnostics of stone disease and its treatment.
1. Introduction.
2. The development of urinary calculi as a consequence of
infection by urease-producing bacteria. 2.1. Role of urease.
2.2. Influence of extracellular polysaccharides. 2.3. Methods
of treatment. 3. Nanobacteria general characteristics. 3.1. Nanobacteria
as a new cause of kidney stones formation. 4. Summary
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