ANALYSIS OF SHEAR-DEPENDENT BACTERIAL ADHESION KINETICS TO BIOMATERIAL SURFACES

A methodology and analysis is presented to quantitatively characterize bacterial attachment and detachment kinetics on biomaterial surfaces in a laminar flow field as a function of shear stress. The spatial distribution of adherent bacteria on the surface of a radial-flow chamber is monitored via automated videomicroscopy with motorized three-axis stage and focus control, allowing rapid automated measurement of the attached cell density as a function of time and radial position. Intrinsic rate constants for attachment and detachment are defined and estimated by fitting mathematical models to the resulting data. The model for cell attachment accounts for the global transport of cell in the chamber to estimate the cells concentration near the collector surface. The model for cell detachment accounts for heterogeneity in the adhesion energy of the attached cell population. These models yield first-order attachment and detachment rate constants that intrinsically reflect the probabilities of bacteria attachment and detachment as a function of applied shear stress, depending on only the local interactions between the cell and the surface. The validity of each model was tested by statistical analyses of the goodness-of-fit to data that resulted from a study comparing adhesion of Staphylococcus aureus to three different polymeric surfaces of varying surface properties and adhesive prolein coatings.