Calcium Phosphate Crystal Formation in Escherichia Coli from Human Urine: An in Vitro Study

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Abstract
E. coli with no demonstrable urease activity was inoculated into filter sterilized urine obtained from a healthy volunteer subject with no history of stone disease and then incubated at 37.degree. C. Bacteria were recovered at intervals between 1-10 days. Urinary pH was stable as compared to control urines and spontaneous crystal precipitation was not noted in controls. Recovered organisms were analyzed by X-ray powder diffractometry. An uncharacterized mineral phase (UMP) was first evident after 6 days. Calcium phosphate in the form of brushite and hydroxyapatite was apparent at 7 and 10 days, respectively. This suggests a role for bacteria in calcium phosphate crystal formation in urine apart from urease activity and may contribute to the calcium phosphate component of urinary calculi.