Elution of vancomycin and tobramycin bonded to vascular grafts

The elution of vancomycin and tobramycin from vascular grafts sealed with c ollagen and human blood was studied in vitro. The release of antibiotics wa s measured in three different types of soaked grafts, including grafts soak ed with antibiotic after being sealed with albumin, those sealed with antib iotic and albumin mixture and those impregnated with fresh blood and antibi otic mixture. Each antibiotic was tested at two different concentrations, i .e. 5 mg/ml and 10 mg/ml for vancomycin and 2 mg/ml and 5 mg/ml for tobramy cin, The eluted antibiotic concentrations were determined by the fluorescen ce polarization immunoassay, Initially large quantities of antibiotics were quickly eluted, depending on the amount of antibiotic mixture. A measurabl e amount of vancomycin was released for 3 days. There was no difference bet ween the elution kinetics of the two antibiotics from the three different s oaked grafts (p>0.05). Antibiotic-soaked grafts provided zones of inhibitio n against Staphylococcus aureus on Trypticase soy agar plate for up to 24 h . These results suggest that local application for 24 h of vancomycin or tobr amycin with vascular grafts may be effective to prevent graft infection as shown by the fluorescence polarization immunoassay.