Silicone-covered metal stents - An in vitro evaluation for biofilm formation and patency

Self-expanding metal stents are being used more commonly to prevent: biliar y tract obstruction. Silicons-covered self-expanding metal stents (Wallsten t, Schneider, Inc.) have been developed to prevent tumor ingrowth. Biofilm formation and occlusion material in silicone-covered self-expanding metal s tents compared to standard polyethylene stents were examined in an in vitro model. Matched pairs of polyethylene and silicone-covered metal stents wer e perfused with infected bile for 8, 12, and 16 weeks at a rate of 0.5 cc/m in at 37 degrees C, Two reservoirs fitted with silicone-covered metal stent s had ampicillin/sulbactam added and were perfused for 16 weeks. The stents were then analyzed by scanning electron microscopy and light microscopy fo r biofilm formation and presence of occlusion material. The two ampicillin/ sulbactam-treated stents showed no biofilm formation. Biofilm was seen on a ll of the remaining stents. There was a difference in occlusion thickness b etween the 8- and 16-week polyethylene stents, and no difference between th e biofilm thickness at 8, 12, or 16 weeks in die silicone-covered metal ste nts. Silicone-covered self-expanding metal stents will likely extend patenc y rates in malignant obstructive jaundice by providing a larger lumen for b ile flow and allowing cyclical antibiotics to prevent bacterial biofilm for mation.