IN-VIVO TREATMENT OF INFECTED PROSTHETIC GRAFT MATERIAL WITH UROKINASE - AN ANIMAL-MODEL

PURPOSE: Pyogenic infection of vascular grafts represents a serious co mplication that may necessitate graft removal. If better treatment met hods could be developed, perhaps some infected grafts could be salvage d and not removed. This study reports an animal model that evaluates t he sterilization of contaminated vascular graft material implants with urokinase and antibiotics. MATERIALS AND METHODS: Polytetrafluoroethy lene (PTFE) implants were incubated overnight in a known concentration of bacteria (Staphylococcus epidermidis) and were then implanted subc utaneously into four groups of anesthetized hamsters. The first group (control) received no treatment. The second group received urokinase i njections twice daily into each abscess. The third group received intr aabscess urokinase and systemic gentamicin twice daily. The fourth gro up received only systemic gentamicin. The hamsters were killed after 1 week. The graft implants and surrounding tissues were excised and sub mitted for quantitative cultures. RESULTS: With use of a cutoff value of 100 organisms per milliliter, below which the abscesses were consid ered noninfected, the following rates of noninfectivity were observed: group 1 (control), 5% noninfected; group 2 (urokinase only), 19.4%; g roup 3 (urokinase and gentamicin), 63.2%; and group 4 (gentamicin only ), 32.5%. The noninfectivity rate of group 3 was significantly higher than that of all other groups combined (P < .001) and was significantl y better than that of group 4 alone (P = .013). CONCLUSION: The combin ation of intraabscess urokinase and systemic gentamicin is very synerg istic in graft sterilization. Urokinase may assist in the degradation of both fibrin and the biofilm produced by S epidermidis, thus improvi ng penetration of antibiotics and local host defense mechanisms.