This invention relates to a method and compositions for modification of medical devices, such as implantable catheters, in particular, urinary catheters, to enhance formation of a high density and stable biofilm comprising non-pathogenic organisms which inhibit the growth and colonization of pathogens causing device-associated infections, such as urinary tract infections. Catheter-associated urinary tract infection (CAUTI) is the most common hospital-acquired infection, accounting for over 1 million cases annually and 30-40% of healthcare-associated infections in the US. This invention is also related to a method and compositions for storage and use of the medical devices coated with a non-pathogenic biofilm. This invention ls yet also related to a method and compositions for modification of implantable medical devices, such as indwelling catheters used for dialysis or urinary drainage (e.g., intravenous, intraperitoneal, or intravesicular) with antifouling polymers, and/or antimicrobial agents.