Quinupristin/dalfopristin bonding in combination with intraperitoneal antibiotics prevent infection of knitted polyester graft material in a subcutaneous rat pouch model infected with resistant Staphylococcus epidermidis

Objective: to investigate the efficacy of quinupristin/dalfopristin in the prevention of prosthetic graft infection in a rat subcutaneous pouch model. Methods: graft infections were established in the subcutaneous tissue of 140 male Wistar rats by implantation of Dacron prostheses followed by topical inoculation with Staphylococcus epidermidis with intermediate resistance to glycopeptides. The study included one group without contamination, one contaminated group without prophylaxis, one contaminated group that received 50 mg/l quinupristin/dalfopristin-soaked graft, one contaminated group that received 10 mg/kg intraperitoneal levofloxacin, one contaminated group that received 3 mg/kg intraperitoneal doxycycline, and two contaminated groups that received 50 mg/l quinupristin/dalfopristin-soaked plus 10 mg/kg intraperitoneal levofloxacin or 3 mg/kg intraperitoneal doxycycline. Each group included 20 animals. The grafts were removed after 7 days and evaluated by quantitative culture. Results: quinupristin/dalfopristin showed a significantly higher efficacy than levofloxacin and doxycycline, even though quantitative graft cultures for rats that received only quinupristin/dalfopristin-soaked graft showed bacterial growth. Otherwise, the efficacy of levofloxacin was similar to that of doxycycline. Only the group treated with quinupristin/dalfopristin combined with levofloxacin or doxycycline showed no evidence of staphylococcal infection. Conclusions: quinupristin/dalfopristin as adjunctive topical antibiotic prophylaxis can be useful for the prevention of vascular graft infections caused by staphylococcal strains with high levels of resistance.