Less-invasive and highly effective method for preventing methicillin-resistant Staphylococcus aureus graft infection by local sustained release of vancomycin.

OBJECTIVE: Methicillin-resistant Staphylococcus aureus graft infection is one of the most serious complications of vascular surgery. Vancomycin is a potent antibiotic against methicillin-resistant S. aureus; however, systemic administration of vancomycin is not very effective against methicillin-resistant S. aureus graft infection. Therefore, we investigated whether a local sustained release of vancomycin prevents methicillin-resistant S. aureus graft infection.

METHODS: We have developed a poly-L-lactide-co-caprolactone sheet that enabled sustained release of vancomycin for 2 weeks. An expanded polytetrafluoroethylene vascular graft patch (1.5 mm2) was sutured at the anterior wall of the incised murine abdominal aorta. Methicillin-resistant S. aureus (1.0 x 10(3) colony-forming units) was inoculated onto the graft surface. Thereafter, the graft was treated as follows (n = 6 each): no treatment (control group), local injection of an aqueous solution of vancomycin (vancomycin solution group) and local implantation of poly-L-lactide-co-caprolactone containing vancomycin (vancomycin-PLCA group). After 7 days, the graft and blood were sampled and cultured.

RESULTS: The methicillin-resistant S. aureus counts in the grafts of the vancomycin-PLCA group were significantly lower than those of the other groups. Blood cultures of the vancomycin-PLCA group were all negative, whereas those of the other groups were all positive for infection. The survival rate in the vancomycin-PLCA group at 28 days was considerably higher than that in the control group (83.3% vs 16.7%).

CONCLUSIONS: A local sustained-release sheet containing vancomycin reduced methicillin-resistant S. aureus counts in the infected vascular grafts, prevented sepsis, and drastically improved survival rates. This can be used as a highly effective and less-invasive adjunctive treatment method for preventing prosthetic methicillin-resistant S. aureus graft infection.