Abstract
The mortality patterns and the LD50/30 for mice free from Enterobacteriaceae, mice contaminated with Enterohacter cloacae, and mice inoculated with Escherichia coli, Klebsiella pneumoniae or Proteus vulgaris were examined after whole-body irradiation with γ rays. No clear differences were observed among the infected groups, but there were clear differences between them and those negative for Enterobacteriaceae. The LD50/30 of Enterobacteriaceae-positive mice was similar to that for conventional mice. All 4 nonpathogenic Enterobacteriaceae had very similar detrimental effects on mice after lethal irradiation.