Resistance induced against parenteral and aerosol klebsiella pneumoniae infection in mice by specific and nonspecific immunization.

Quantitative data were gathered concerning the extent of resistance induced in mice immunized by specific and nonspecific means and subsequently challenged both parenterally and by aerosol. Animals were immunized specifically by subcutaneous injection of formalin-killed Klebsiella pneumoniae Type I which was also employed as challenge organism. The intraperitoneal LD50 was 30 bacilli. Nonspecific resistance was induced by injection of a Boivin (Difco) perpetration of Salmonella tvphimurium endotoxin. Nonspecific resistance was highest 24 hours after injection of 10 ug of endotoxin. At this time, over half the mice survived challenge with 10(2) but not 10(3) LD50. Specifically immunized mice were resistant to as much as 10(5) LD50 depending upon route of immunization. Potency ratios for parenteral challenge were: nonspecific to normal, 100, specific to normal, 10(4) to 10(5), specific to nonspecific, 10(2) to 10(3). Specific immunization protected against aerosol challenge in the LD100 range. Nonspecifically immunized animals showed significant prolongation of survival time but the 30 day mortality was similar to the control group. When aerosol challenge was in the LD50 range, the 30 day mortality showed differences between non-specifically immunized animals and control groups. The differences were not significant using groups of 30 mice.