TISSUE-REACTIONS TO BACTERIA-INOCULATED RAT LEAD SAMPLES .2. EFFECT OF LOCAL GENTAMICIN RELEASE THROUGH SURFACE-MODIFIED POLYURETHANE TUBING

A surface modification technique was developed to achieve controlled r elease of gentamicin from implanted polyurethane (PU) rat lead samples . PU tubing first was provided with an acrylic acid/acrylamide copolym er surface graft and then loaded with gentamicin. This surface modific ation technique resulted in release of gentamicin base (GB) and was ap plied either to the inner luminal surface only (PU-GB-lx) or to both t he inner and outer surfaces (PU-GB-2x). First we investigated whether the early tissue response was harmfully compromised when surface-modif ied rat lead samples were implanted without any infectious challenge. Additionally, the efficacy of this type of local gentamicin therapy wa s investigated by establishing its effect on tissue response and its a bility to prevent lead-related infections after inoculation with Staph ylococcus aureus. It was demonstrated that the applied surface modific ation(s) did not induce adverse effects although an increase in the in filtration of granulocytes and macrophages and an increase in the form ation of wound fluid and fibrin were observed. This effect was stronge r with PU-GB-2x than with PU-GB-lx. With bacterial inoculation the app lied surface modification successfully suppressed the infectious chall enge, PU-GB-2x more effectively than PU-GB-lx. PU-GB-2x also was more effective when compared to the gentamicin-delivery methods discussed i n the first part of this two-part study, i.e., release through a vicin al gentamicin-containing collagen sponge and preoperative gentamicin s olution-dipping of rat lead samples. (C) 1997 John Wiley & Sons, Inc.