Dynamic adhesion of cells to surfaces is a vital step in a variety of biochemical and physiological phenomena. Bacterial adhesion is responsible not only for problems associated with biofouling and biofilm formation in the biochemical industry but also in the initiation of certain infectious diseases. In this study, we report the effect of critical parameters, such as receptor and ligand densities and shear rate, on receptor-mediated dynamic bacterial adhesion. Adhesion of a pathogenic strain of Staphylococcus aureus to immobilized collagen was studied. The receptor density on the cell surface was varied by harvesting cells at different growth times and was quantified using flow cytometry. Dynamic adhesion experiments were conducted over a range of physiologically relevant shear rates (50 to 1500 s(-1)) using a parallel-plate flow chamber. Video microscopy coupled with digital image processing was employed to quantify adhesion. A semiquantitative comparison between experimental results and theoretical data obtained using a previously proposed mathematical model was also performed. The results suggest that dynamic adhesion is dependent on receptor density and shear rate, but independent of ligand density. This report demonstrates the feasibility of using bacteria to study fundamental aspects of receptor-mediated dynamic adhesion. (C) 2000 John Wiley & Sons, Inc.