Bacterial adherence to graft tissues in static and flow conditions

Various conduits and stent-mounted valves are used as pulmonary valve graft tissues for right ventricular outflow tract reconstruction with good hemodynamic results. Valve replacement carries an increased risk of infective endocarditis (IE). Recent observations have increased awareness of the risk of IE after transcatheter implantation of a stent-mounted bovine jugular vein valve. This study focused on the susceptibility of graft tissue surfaces to bacterial adherence as a potential risk factor for subsequent IE.

Adhesion of Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus sanguinis to bovine pericardium (BP) patch, bovine jugular vein (BJV), and cryopreserved homograft (CH) tissues was quantified under static and shear stress conditions. Microscopic analysis and histology were performed to evaluate bacterial adhesion to matrix components.

In general, similar bacteria numbers were recovered from CH and BJV tissue surfaces for all strains, especially in flow conditions. Static bacterial adhesion to the CH wall was lower for S sanguinis adhesion (P < .05 vs BP patch). Adhesion to the BJV wall, CH wall, and leaflet was decreased for S epidermidis in static conditions (P < .05 vs BP patch). Bacterial adhesion under shear stress indicated similar bacterial adhesion to all tissues, except for lower adhesion to the BJV wall after S sanguinis incubation. Microscopic analysis showed the importance of matrix component exposure for bacterial adherence to CH.

Our data provide evidence that the surface composition of BJV and CH tissues themselves, bacterial surface proteins, and shear forces per se are not the prime determinants of bacterial adherence.