Medical devices for implantation in a body vessel are provided. A medical device can include a support member enclosing an antimicrobial coating defining a drainage lumen extending through the support member. The antimicrobial coating preferably includes a metal alloy comprising beryllium, nickel, copper, cobalt and/or silicon. The metal alloy is desirably embedded in a porous biostable material, such as an ethylvinylacetate copolymer, configured to retain oxides of the antimicrobial material while being sufficiently porous to permit fluid in the drainage lumen to penetrate the antimicrobial coating. The medical device may be configured, for example, as a biliary or pancreatic stent.