The present invention provides methods of protecting irradiated eukaryotic cells such as irradiated mammalian epithelial cells, from the deleterious effect of microbial pathogens such as Pseudomonas aeruginosa. The invention also provides methods of protecting irradiated organisms from such deleterious effects, resulting in reduced mortality and morbidity. Further provided are kits containing relatively high molecular weight biocompatible polymers such as polyethylene glycol, optionally supplemented with a protective polymer such as dextran and/or essential pathogen nutrients such as L-glutamine, along with instructions for administration to organisms to be exposed to radiation.