Bacteria are able to adhere and live on solid surfaces in communities of one or more species, so called biofilms. Biofilms on human tissue or on medical devices, which are in contact with the human body, can lead to serious infections. On urinary catheters biofilm formation is a well-known example and catheter-associated urinary tract infections are one of the most frequently nosocomial infections worldwide. Therefore the adhesion of single bacteria on catheter materials is one of the initial steps. Concerning the fact, that every surface is coated by molecules out of the ambient medium, binding always occurs between bacteria and this conditioning film. With regard to this fact, we characterized the chemical composition of urinary conditioning films on different materials with XPS. In detail the concentrations of the two major urinary proteins human serum albumin (HSA) und Tamm-Horsfall-Glycoprotein (THP) have been detected quantitatively on the surfaces by a combination of immunofluorescence and QCM. In a further step adhesion forces between bacteria and four materials with different hydrophobic properties have been examined quantitatively by force spectroscopy. The effect of urinary coatings on the adhesion forces has been investigated. Finally we could correlate the results of this nanoscopic measurement setup with macroscopic microbiological test systems.