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Arm , H. G. (Naval Medical Research Institute, Bethesda, Md.), T. M. Floyd, J. E. Faber, and J. R. Hayes . Use of ligated segments of rabbit small intestine in experimental shigellosis. J. Bacteriol. 89: 803–809. 1965.—Inoculation of ligated segments of small intestine in living rabbits with broth cultures or resting-cell suspensions of recently isolated strains of Shigella caused distension of the segments by accumulation of exudate within 12 hr. Histological changes characteristic of an inflammatory response were similar to those of human bacillary dysentery. Tissue response and accumulation of exudate preceded demonstrable increase in numbers of shigellae inoculated as 2 × 10 10 resting cells. Capability of shigellae to provoke intestinal response was not related to any particular serological group. The active principles concerned with eliciting intestinal response were associated only with preparations containing living organisms. Ability of recently isolated strains to elicit response diminished rapidly during culture on artificial media. The capability was preserved indefinitely by lyophilization soon after isolation from acute bacillary dysentery infections of man. Advantages of using shigellae recently isolated for investigating possible mechanisms of pathogenesis were indicated. During the summer months, the rabbit small intestine was refractory to the activity of shigellae, and positive responses were not observed. Use of ligated segments of rabbit small intestine qualified as an indicator of virulence for the rabbit; and, virulence for the rabbit showed a high degree of correlation with a short period of culture of shigellae on artificial media after isolation from human bacillary dysentery infections.

The inclusion of motile Proteus species in the intestinal flora introduces great obstacles to the isolation of many organisms of medical importance. The isolation of Bacterium necrophorum is especially difficult since the conditions1 favoring its growth are also favorable for the swarming of Proteus, namely blood agar plate medium in an environment of high humidity accompanying anaerobic conditions.2 The swarming of Proteus has received attention in studies of the variation of this organism. Results of these studies indicate beyond doubt that this property is due to the active motility of the organism, which is in turn dependent upon the presence of flagellae.3 Several methods have been devised to prevent the swarming of Proteus on the surface of solid medium. Ethyl alcohol and phenol have been used to destroy the flagellar component of the organisms. Other investigators have used narcotics to inhibit motility. One worker attacked the problem by pouring a layer of agar over a streaked plate. Some of these methods were tried in our studies with Bact. necrophorum.

Summary and Conclusion One hundred Egyptian village children were immunized with 1.0 ml. of a Shigella flexneri 3 vaccine, given in three divided doses of 0.3 ml., 0.3 ml. and 0.4 ml. at weekly intervals. A similar group of unvaccinated children were observed as controls. During a six month observation period following vaccination, 25 (26.8 per cent) of the children who received the vaccine were found to be infected with Shig. flexneri 3 organisms as compared with 18 (20.4 per cent) of the children in the control group. The number of infections with other Shigella organisms, and the number of episodes of diarrheal disease, was approximately the same in both groups of children. Immunization with a Shigella flexneri 3 vaccine was not effective in preventing Shigella flexneri 3 infections, or diarrheal disease associated with these organisms, in a group of Egyptian village children living in a highly endemic environment.

Summary Egyptian village children in the first six months of life, while exposed to a highly endemic environment and experiencing a higher incidence of diarrheal disease, were less frequently infected with Shigella organisms than were older children. Shigella organisms were not recovered from infants in the neonatal period even during seasons of high incidence of infection in older subjects. Shigella infections were most prevalent during the second and third years of life.