Platelets increase S aureus adhesion under shear stress. (A) Microparallel flow chamber perfusions over coated collagen with fluorescently labeled WT, vwb, and coa/vwb strains in the presence of plasma and platelet-rich plasma (preincubation 37°C for 15 minutes) at 1000 seconds⁻¹. Addition of dabigatran (500 nM) or eptifibatide (7.5 μg/mL) where indicated (n ≥ 5). (B) Perfusion over coated collagen with WT, vwb, and coa/vwb strains in platelet-rich plasma at 1000 seconds⁻¹. Platelets were labeled with rhodamine-G (preincubation 37°C for 15 minutes). Adhesion of platelets was lower when perfused with a strain lacking vWbp compared with WT and was further reduced when perfused together with a mutant strain lacking both coagulases (vwb/coa) (n ≥ 4). All results are expressed as mean ± SEM. *P < .05, **P < .01. (C) SEM image (×20 000) of WT perfusion in PRP over collagen at 1000 seconds⁻¹, illustrating the interactions among bacteria, fibrin, and platelets. Bar represents 1 μm. (D) SEM image (×5000) of WT perfusion in PRP over collagen at 1000 seconds⁻¹. Bar represents 2 μm. Full white arrows indicate bacteria; dotted white arrows indicate platelets.