[Citrobacter persistence in the intestinal tract of guinea pigs depending on the microecological status]

Gnotobiological studies were conducted on germ-free guinea pigs. Association of the animals with the citrobacteria 5396/38 strain led to the reproduction of these bacteria in numbers exceeding the sum total number of all the representatives of the normal microbial flora in the conventional animals. Association lasting for a period of 46 days caused no antibody formation in the blood serum of these animals in difference to conventional guinea pigs immunized parenterally. Conventionalization of the monoflora guinea pigs served as the beginning of population of the intestinal tract by other microbial representatives which replaced the first culture. Biochemical properties of the citrobacteria strains isolated from the monoflora strains were identical to the properties of the initial culture. After the monoflora animals were let out of the isolation cage the citrobacteria strains displayed changes of some differential-diagnostic signs. Passage through the macroorganism of the citrobacteria stain proved to lead to the changes in the antigenic structure.