New biliary endoprosthesis less liable to block in biliary infections: Description and in vitro studies

Objective: To rest in vitro stents made from a new biomaterial that is less liable to encourage adhesion of bacteria that may lead to blockage of the stent. Design: Laboratory experiment. Setting: University hospital, Italy. Material: 15 polyethylene biliary endoprostheses that had been removed endo scopically a mean of 151 days (range 55-416) after insertion. PUPA, a bioma terial that contains polyamidoamine cross-linked to polyurethane chains. Th is can bind large quantities of heparin and HyaIS(x) (hyaluronic acid at a different stage of sulphation) in a stable fashion. Main outcome measures: Incidence of blockage and growth of pathogens in the polyethylene biliary prostheses. Adhesion of pathogens to PUPA in vitro on electron microscopy. Results: 12 of 15 polyethylene prostheses were blocked by brown concretions composed of calcium bilirubinate, palmitate, and little cholesterol. All c oncretions grew more than one pathogen, and the growth always included Esch erichia coli. Of the 5 PUPA stents rested, only 1 had bacteria sticking to their surfaces. Conclusion: These results confirm previous studies that showed that HyalS(x ) appreciably inhibited the adhesion of bacteria and is therefore a suitabl e material for the manufacture of biliary stents.