Abstract
Summary
Groups of rats were exposed in a cold room maintained at 1.7°C for periods ranging from 0 to 36 days and showed little or no reduction in body temperature during this period. These groups, along with appropriate controls maintained in a normal temperature environment, were then given either 1 or 4 intravenous injections of a broth culture of Streptococcus mitis JH 26. Survivors were killed for pathologic study 7 days after the first bacterial inoculation. In control groups and in the one group of cold rats returned to a normal temperature environment after the bacterial inoculation, the incidence of severe bacterial endocarditis was 16-19% and mortality rate was 0-9%. In the groups kept in the cold room 1-36 days before and 7 days after the first inoculation, the incidence of severe bacterial endocarditis was 82-100% and the mortality rate 41-73%. The corresponding figures for rats kept in the cold room after but not before inoculation were 50 and 43% respectively. In rats acclimatized to cold for 35-36 days, the mortality rate was lower and length of survival was longer than in rats placed in the cold room only one day before bacterial inoculation.
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