Protocol Development To Examine The Effect of Bulk Shear Exposure On Staphylococcus aureus Surface Adhesion

Lisa Mascari and Julie M Ross
Chemical and Biochemical Engineering
University of Maryland, Baltimore County

Staphylococcus aureus is a pathogenic organism with antibiotic resistance 
that binds to collagen under static and dynamic conditions. In vivo, 
blood-born bacteria are exposed to shear stress in the bulk phase as they 
travel through the vasculature.  For the bacteria to initiate an infection, 
the cells must also adhere to the vascular surface or subendothelium in the 
presence of shear stress. This study attempts to mimic exposure of the cells 
to bulk shear in vivo prior to investigating dynamic surface adhesion.  A 
constant stress rheometer is used to expose the cells to bulk shear before 
the dynamic adhesion is quantified using a parallel plate flow chamber, phase 
contrast videomicroscopy and digital imaging processing. The dynamic surface 
adhesion results from cells exposed to bulk shear are compared to dynamic 
surface adhesion results of control cells. The results of this study will be 
used to determine whether exposure to bulk shear stress affects dynamic S. 
aureus surface adhesion.