Vascular Graft Pre-Treatment with Daptomycin Prior to Implantation Prevents Graft Infection with Staphylococcus aureus in an In Vivo Model.

Abstract

Background: Infection of vascular grafts is a life-threatening complication in cardiovascular surgical procedures. This experimental study tested the efficacy and possible harmful effects of daptomycin pre-treatment in vivo in prevention of vascular graft infection caused by Staphylococcus aureus. Methods: Polyethylene terephthalate (PET) patches (5 × 7 mm) were sewn on the infra-renal abdominal aorta of 32 New Zealand White rabbits. Before implantation, patches either were pre-treated for 15 min with daptomycin in one group (n = 13) or left untreated in the other group (n = 13) before contamination with 100 mcL bacterial solution (1 × 1010 colony-forming units [CFU] per mL). Six animals with uninfected patches without (n = 3) or with (n = 3) daptomycin pre-treatment served as controls. On postoperative day seven, all patches were explanted, washed with phosphate buffered saline, and sonicated to release viable adherent bacteria. The CFUs were quantified and aortic tissues were histologically examined. In addition, bacterial adherence on the patches was analyzed using scanning electron microscopy (SEM). Results: In the daptomycin pre-treatment group, significantly reduced numbers of CFUs on the patches were observed, compared with non-pre-treated patches (3.21 × 102 ± 1.02 × 103 mL-1 vs. 5.18 × 105 ± 1.05 × 106 mL-1; p < 0.001). Peri-vascular abscesses were visible in all rabbits with S. aureus infected patches, whereas no signs of inflammation were found in the daptomycin pre-treatment group or the control groups. Conclusions: Daptomycin showed excellent in vivo antibacterial activity against vascular graft infection caused by S. aureus, compared with non-pre-treated grafts, resulting in a significant reduction in bacterial infection and prevention of abscess formation. No harmful effects of the antibiotic pre-treatment could be observed.