VIRULENCE AS A FACTOR IN SALMONELLA INFECTION IN MICE MAINTAINED IN THE COLD
Technical documentary rept.
BRYN MAWR COLL PA
Pagination or Media Count:
The object of this study was to determine possible differences in the course of salmonellosis in mice maintained at 25 C and others kept at 5 C, and to uncover, if possible, mechanisms responsible for such differences. The LD50 dose for mice of Salmonella typhimurium, strain RIA, is 4.6 X 10 to the 5th power for animals individually housed without bedding and maintained at 25 C. It is 3.8 X 10 to the 3rd power for animals similarly housed but kept at 5 C. An intravenous injection of 0.1 ml of saccharated iron oxide Proferrin two hours prior to infection lowers the LD50 to 4.9 X 10 to the 3rd power and 4.0 X 10 to the 1st power for mice kept respectively at 25 C and at 5 C. Low environmental temperature and blockage of the reticuloendothelial system RES lower the resistance of mice to about the same degree, but low temperature and RES impairment together lower resistance as if each is acting independently. Doubling the volume of Proferrin more than doubles the changes in susceptibility to infection manifested by the mice but this amount seems to be toxic for mice. Even more important is the incident of staphylococci found in liver or kidney of mice infected with S. typhimurium and kept at 5 C.