Methylene blue and 2 nm gold nanoparticles were incorporated into commercial PVC catheters by use of a simple “swell–encapsulation–shrink” method using acetone–water mixtures. Neither the methylene blue nor the nanogold leached into aqueous solution and the assemblage was stable to photodegradation upon laser irradiation. Exposure of the modified catheters to red laser light for 4–8 minutes induced the lethal photosensitisation of Staphylococcus epidermidis and Escherichia coli. Results from time-resolved EPR spectroscopy suggested that enhanced methylene blue triplet state production occurs in the presence of 2 nm gold nanoparticles. The implication being that the levels of reactive oxygen species are higher in these co-doped materials than with methylene blue alone.