A method for immobilizing dyes and antimicrobial agents on a polymeric cover or housing for a medical device is disclosed and described. The surface may be that of a catheter, a connector, a drug vial spike, a bag spike, a prosthetic device, an endoscope, a surface of an infusion pump, a key pad, a touch screen or a handle. The surfaces may also be one or more of those associated with a infusion of a medicament or dialysis treatment, such as peritoneal dialysis or hemodialysis, where it is important that the working surface for the dialysis fluid be sterile. These surfaces include connectors for peritoneal dialysis sets or for hemodialysis sets, bag spikes, dialysis catheters, and so forth. A method for determining whether a surface has been sterilized, and a dye useful in so indicating, is also disclosed.