A study of persistence of shigella in intestinal tract of mice

Effect of starvation as pretreatment

Abstract

The Progress in experimental dysentery has not been remarkable, recently however, there have been several investigations using cortison, opium, antibiotics, liver-toxin and starvation which may increase susceptibility of the host or decrease resistance to the dysentery infection.
Starvation is applied in this experiment as pretreatment to produce experimental shigellosis. Through the study of persistence of shigella in intestinal tract of mice, efforts were made to understand the mechanism of onset of dssentery.
1) As for host factors, resistance of mice, lesions of liver and changes in the intestinal flora during the starvation were studied. The starvation period is limited within two days, because most of the mice do not tolerate longer fasting period.
Fatty degeration was found in the liver of the starved mice, and this suggested that some change in the intestinal physiology might be occurring.
From these findings, it was concluded that the intestinal flora might be deranged and distribution of gram positive cocci and gram negative bacilli in intestines was, changed as the starvation went on,
Mice which were starved for two days were administered a streptomycine resistant strain of shigella flexneri 2b for three days by stomach-tube.
In this experimental group and in the streptomycine-pretreated group, the excretion period of shigella was prolonged. However, the percentage of positive stool culture in. the starved group (% of positive stool culture =number of positive stool culture/number of stool cultur was distinctly higher than that of the streptomycine-pretreated group.
2) In order to understand Parasite-factors resistant strain and sensitive strain ofshigella flexneri 2b were administered to the streptomycine-pretreated group, to the starved group, and to the untreated group.
Excretion period of shigella flexneri 2b was prolonged in the former two groups. Furthermore in the control group the resistant strain was longer excreted than the sensitive strain.
On the contrary, in the pretreated group excretion period of sensitive strain was longer than of resistant strain. Also, the percentage of positve culture in treated mice which were administered the sensitive strain was high.
Whether the strain which persisted for a long time in mouse intestine has any ability to multiply in mouse or not, was not proved.
3) Persistence and proliferation of the pathogenic bacilli in the intestine of mice are more frequently observed in the animal with few intestinal flora and this phenomenon is enhanced by the streptomycine treament and especially by the starvation.