Experimental Shigella Infections

[摘要] Sections of tissue obtained from guinea pigs succumbing to a fatal enteric infection of Shigella flexneri 2a were examined by fluorescent antibody and conventional histologic procedures to determine the nature and extent of a fatal infection.Shigellae were neither cultured nor visualized in any organs outside of the intestinal tract. In most of the animals studied which succumbed to infection at 24 hr ulcerative lesions of the mid-and terminal ileum and cecum were noted. In animals dying 72 to 96 hr postchallenge ulcerative lesions of the duodenum-jejunum, or midileum were never seen. These animals consistently had large ulcerations of the cecum and colon, whereas lesions of the terminal ileum were rare.In all of the challenged animals examined, shigellae could be found in the lamina propria of solitary villi without apparent loss of mucosal continuity. Examination of sections of intestine from animals sacrificed at various times after challenge dose revealed that shigella may invade the lamina propria of these villi within 8 hr. It is postulated that intestinal lesions of bacillary dysentery may depend on the presence of shigellae within the lamina propria as a requisite to the formation of an ulcer. Whenever ulcers formed they always contained specifically fluoreseing dysentery bacilli, and in early stages they did not appear to be contaminated with other microorganisms.Control experiments in which large doses of heat-killed Shigella flexneri 2a or live Escherichia coli were fed to guinea pigs showed no production of ulcerative lesions.Attempts to dctect antigenic products of shigellae in the organs of animals moribund from the experimental infections were not successful.

[学科分类] 生物科学（综合）