An Ecological Study of Infected Urinary Stone Genesis in an Animal Model

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Abstract
Direct molecular and morphological techniques of modern microbiology were used to monitor the sequential development of bacterial microcolonies and biofilms in a rat model of urinary infection and to demonstrate that the urease activity of the infecting organisms sets in course a series of fractions in which struvite and apatite crystals develop within the matrix of the enlarging bacterial aggregate. This forms multiple stone nidi on the uroepithelial surface upon which succeeding bacterial biofilms develop and with the incorporation of other urine components, such as urinary mucoproteins, establishes a matrix skeleton that becomes mineralised, thus allowing for the growth of the stone in concentric layers. To arrive at this hypothesis, we studied infection stonegenesis using a newly developed model for infection-induced bladder stone formation in the rat. We examined in detail the sequential events in the evolving microbial ecology of progressive struvite calculogenesis, using conventional microbiological techniques, direct ultrastructural observation, newly developed ultrastructural cytochemical localisation techniques and immunological procedures for stabilisation of the biofilm glycocalyx and stone matrix in the rat model. It was concluded that the organic glycocalix material secreted by the associated bacteria comprises a substantial and aetiologically important part of the infection stone calculogenesis and matrix production.