MIYA, MARCUS AND PHELPS 



Studies on Klebsiella Pneumoniae Passed Through Mice Maintained 

 at Low Ambient Temperatures 



The previous section revealed information concerning the meta- 

 bolic behavior of the bacterial challenge agents at different tempera- 

 tures; however, it was notpossible to predict the metabolic behavior 

 and virulence of the organisms when given to an animal that was 

 acclimatized tothe cold. In order to see if any changes did occur, the 

 following experiment was carried out. 



A single isolated colony of K. pneumoniae was inoculated into 

 tryptose phosphate broth (Difco) and incubated for 18 hours at 

 37° C. One tenth ml of broth suspension of organisms per mouse 

 was given intraperitoneally. At the end of 24 hours, the surviving 

 mice were sacrificed by decapitation. The peritoneal cavities were 

 opened aseptically and the peritoneal exudate was removed. The 

 exudate was reinjected into a number of mice after a sample had 

 been seeded to heart infusion blood agar plates (Difco) for isolation 

 and identification procedures. This procedure was repeated each 

 day for 7 days. The inoculated mice were kept at either 21° C or 

 2° C during this time of organism passage. The mice had been kept 

 at these respective temperatures for 40 dayspriorto injection with 

 the organisms. The K. pneumoniae strain isolated from the animals 

 kept at 2° C was incubated at room temperature (21° C) while the 

 organisms isolated from the animals kept at 21° C were incubated 

 at 370 C. 



The K. pneumoniae passed through mice maintained at 2° C was 

 compared with the K. pneumoniae passed through mice maintained 

 at 21° C with respect to their metabolic behavior and virulence. 

 It is seen in Figure 5 that incubation of both strains at 37° C results 

 in similar growth behavior curves when comparing organisms 

 isolated from the animals maintained at 2° C or at 21° C, Slightly 

 different growth curves in terms of comparison of the two strains 

 were obtained when these organisms were incubated at 32° C 

 (Figure 6). The K, pneumoniae isolated from animals maintained 

 at 2° C showed growth curves almost identical with those obtained 

 at 37° C incubation, whereas the organisms isolated from mice 

 maintained at 21° C show a definite decrease in growth maximum 

 in addition to an increased lag phase. These results suggested that 



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