Use of Ligated Segments of Rabbit Small Intestine in Experimental Shigellosis.

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 x 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.