Infection-resistant materials, and methods of preparing same, suitable for use within the interior of a human or animal body in such forms as vascular grafts prostheses, or other implanted devices. The material is rendered infection-resistant by incorporating therein antimicrobial agents, such as nalidixic acid derivatives or metal salts of nalidixic acid derivatives. In particular illustrative embodiments, silver norfloxacin and silver pefloxacin, are complexed with natural or synthetic polymeric materials such as silk, polyester (e.g., Dacron), polyurethane, polytetrafluoroethylene, or silicone-based material, to provide long-term prevention of infections which may otherwise result during or after surgery or implantation of a device.