In vitro interaction of bacteria with polypropylene/ePTFE prostheses

The infection of an implanted prosthetic material can have serious conseque nces on the tissue integration of the implant and the scarring process in t he host. and may even necessitate replacement of the prosthesis. This study was designed to explore the in vitro effects of Staphylococcus aureus (Sa) and Staphylococcus epidermidis (Se) on polypropylene (PL) and expanded pol ytetrafluoroethylene (ePTFE) prostheses. Fragments of PL and ePTFE were pla ced in a medium previously inoculated with Sa, Sr or Sa + Se (1 x 10(8) cfu Sa or/and Se). Bacterial effects on the biomaterials were evaluated for 30 days through scanning electron microscopy (SEM). In order to confirm the p resence of bacteria on the prostheses, specimens were Gram stained and chal lenged with an antibody against protein-a (a specific Sa bacterial wall com ponent). In both methods, specimens were examined by light microscopy. The presence of bacteria as microcolonies or biofilms was detected at PL filame nt cross-over regions after 30 days. Bacterial colonization of the ePTFE fr agments was observed in internodal areas, which led to the deformation of p rosthetic filaments. The present findings indicate that Sa and Se colonize the cross-over regions of the PL filaments, whereas in ePTFE prostheses. it is the internodal areas which are mostly affected. The latter areas are of difficult access to defence agents. (C) 2001 Elsevier Science Ltd. Ail rig hts reserved.