Reduced Susceptibility of Polytetrafluoroethylene Vascular Prostheses to Colonization by Staphylococcus aureus Following In Situ Endothelialization

Abstract

The impact of endothelialization of polytetrafluoroethylene (PTFE) grafts on susceptibility to experimental colonization by Staphylococcus aureus was studied in a rat model. One hundred and eight grafts (2 mm inner diameter, 5 mm length) were implanted into the infrarenal aorta (54 rats) or the infrarenal caval vein (54 rats). The progress of endothelialization following graft implantation was evaluated by SEM at 1, 3, 7, and 14 days on 6 grafts from each group. We found that the endothelialization was more rapid in caval vein than in aorta: The caval vein grafts were completely endothelialized 2 weeks following implantation compared with endothelialization of approximately 0.5 mm of aorta grafts, measured from each anastomosis. During this time, the resistance to standardized intravenous challenge with 10(8) colony-forming units of S. aureus increased gradually in both groups, and all caval vein grafts tested at 2 weeks were sterile. However, all aorta grafts challenged at 2 weeks were colonized, although to a somewhat lower degree than at earlier challenge. Resistance of PTFE grafts to colonization with S. aureus thus correlated to the degree of endothelialization.

Late Hematogenous Infection of Subcutaneous Implants in Rats

“…challenge with 10 8 S. aureus organisms 3 to 6 months after implantation, yielding infections in 10 to 80% of the animals, depending on the type of graft (17). Interestingly, a similar study with rats revealed that the infection rate of caval vein grafts was reduced from 100% to zero during 2 weeks of implantation as a result of increased endothelialization, while the infection rate of aorta grafts was still 100% after these 2 weeks (26).…”