Bacterial Adhesion and Interaction with Biomaterial Surfaces - Biointerfaces: Where Material Meets Biology - page 375

can induce platelet activation, which is a necessary step in thrombus for-
mation. On the other hand, the activated platelets can also promote bacterial
adhesion on biomaterial surface. Wang et al. studied the adhesion of
S. epidermidis on hydrophobic polystyrene and found that the presence of
platelet increased adhesion more than on a protein adsorbed surface by at
least one order of magnitude. 129
Numerous studies showed that bacterial surface proteins and plasma
proteins are involved in platelet-bacteria interactions. 13,130-132 The former
includes the clumping factors, Fn-binding proteins of S. aureus, 133,134 and
Fg-binding protein SdrG of S. epidermidis. 47 Cox et al. reviewed the bacteria-
platelet interactions and summarized that interactions can be characterized
by the binding of bacteria to platelets either directly through a bacterial
surface protein or indirectly by a plasma bridging molecule that links bac-
teria and platelet surface receptors. 135,136 Platelets are activated by inter-
action with bacteria via either direct interaction or indirectly through
bridging molecules or the secreted bacterial products. Bacteria may be en-
hanced to adhere to biomaterial surfaces.
Plasma proteins play an important role in interaction of bacteria-platelet
on biomaterial surface. Figure 13.3 shows the images of bacteria-platelet
interactions on the polyurethane surfaces which were incubated in phos-
phate buffered solution containing S. epidermidis (1 10 8 CFU mL 1 ) and
platelets (2.5 10 8 mL 1 ) for 1 h with shaking at 250 rpm. Results show that
bacteria adhered on surface and aggregated to form clusters. Although fewer
platelets were observed compared to the numbers of bacteria, most of the
platelets were found to be either entrapped in bacterial aggregates (green
arrows) or co-adherent with bacteria (red arrows), suggesting the formation
of platelet-bacteria aggregates. To study the effect of plasma proteins on
bacteria-platelet interactions, human serum albumin (HSA), Fg and Fn were

d n 3 r 4 n g | 3

.

Figure 13.3 Fluorescent images of S. epidermidis RP62A bacteria and platelets
interactions on polyurethane surface: (a) platelets and (b) bacteria.
Red circles are drawn for comparison of areas between images. Image
size: 226 mm 169 mm.
Reproduced from Xu and Siedlecki 128 with permission from Scientific
Research Publishing.