Radiosensitization of Serratia marcescens by cetylpyridinium chloride. Evidence for membrane-associated events.

Cetylpyridinium chloride has been shown to be an effective radiosensitizer of both oxic and anoxic suspensions of Serratia marcescens in buffer. The related compounds ethylpyridinium bromide and cetyltrimethylammonium chloride exhibited no such radiosensitizing properties at comparable concentrations. It is suggested that the efficiency of cetylpyridinium chloride is due to the combination of lipid-soluble (cetyl) and electron-affinic (pyridinium) moieties within the same molecule, and that these may provide for interaction with a membrane-associated target. Cetylpyridinium chloride did not radiosensitize bacteria suspended in nutrient broth.