Abstract: Systems and methods are provided that reduce the likelihood of infection caused by microorganisms. In general, microorganism population control can be achieved by exposing the population to an effective dose of electromagnetic radiation sufficient to cause a reduction in proliferation of the microorganism, wherein the electromagnetic radiation has a center wavelength between about 385 nm and about 425 nm. In preferred embodiments, the systems and methods described herein can be embodied in catheterization systems.