Pathogenicity of porcine intestinal spirochetes in gnotobiotic pigs

Abstract

Twelve intestinal spirochete strains of porcine origin were characterized on the basis of their phenotypic properties, by multilocus enzyme electrophoresis, and by pathogenicity testing in gnotobiotic pigs. The spirochetes used included two strains of Serpulina hyodysenteriae (B204 and P18A), two strains of Serpulina innocens (B256 and 4/71), one strain from the proposed new genus and species "Anguillina coli" (P43/6/78), and seven non-S. hyodysenteriae strains recently isolated from United Kingdom pig herds with a history of nonspecific diarrhea and typhlocolitis. By multilocus enzyme electrophoresis, five of these were identified as S. innocens, one was identified as an unspecified Serpulina sp., and one was identified as "A. coli." S. hyodysenteriae B204 and P18A, "A. coli" P43/6/78 and 2/7, and three (22/7, P280/1, and 14/5) of the five S. innocens field isolates induced mucoid feces and typhlocolitis in gnotobiotic pigs. None of the other spirochetes produced clinical signs or large intestinal pathology in this model. The "A. coli" strains induced a more watery diarrhea, with lesions present more proximally in the large intestine, than did the other pathogenic spirochetes. S. innocens 22/7 was also tested for pathogenicity in hysterotomy-derived pigs that had previously been artificially colonized with a spirochete-free intestinal flora and shown to be susceptible to swine dysentery. Despite effective colonization, strain 22/7 did not produce any disease, nor was there any exacerbation of large intestinal pathology or clinical signs when pigs with an experimentally induced existing colitis caused by Yersinia pseudotuberculosis were superinfected with strain 22/7. Certain non-S. hyodysenteriae spirochetes are therefore capable of inducing disease in gnotobiotic pigs, but their role as primary or opportunistic pathogens in conventional pigs remains equivocal.

Identification of Serpulina species associated with porcine colitis by biochemical analysis and PCR

“…The disease was referred to as spirochetal diarrhea (25). Diarrhea associated with WBHIS has also been reported by others (6,8,10,20,27,28). Isolation of WBHIS with the capacity to hydrolyze hippurate, but lacking ␤-glucosidase activity, from pigs with diarrhea has been reported (3,5,6), while indole-negative WBHIS with other phenotypes were considered to be nonpathogenic (5,6).…”

“…It was possible to reisolate spirochetes from a suspension of 0.2 g of pig feces in 1 ml of broth which had been inoculated with only 150 spirochetal cells. In a challenge study in gnotobiotic pigs with strains of Serpulina, including S. hyodysenteriae, S. innocens, and strain P43, the number of spirochetes in feces 5 to 10 days postinfection varied from 1 ϫ 10 5 to 2 ϫ 10 9 per g of feces (20), which is equivalent to 2.0 ϫ 10 4 to 4.0 ϫ 10 8 bacterial cells per 0.2 g of feces. The numbers did not differ significantly for pigs with and without clinical signs.…”

CD4+ T‐cell responses and distribution at the colonic mucosa during Brachyspira hyodysenteriae‐induced colitis in pigs

“…In both cases the presence of normal intestinal flora is required for disease development. 2,10 Both pathologies share similar histological lesions, namely thickening of the epithelium with crypt hyperplasia. 41,42 A previous study showed that CD4 + T cells were diminished in the colonic mucosa of pigs with swine dysentery.…”

Pathogenicity of human and porcine intestinal spirochetes in one-day-old specific-pathogen-free chicks: an animal model of intestinal spirochetosis

“…This condition was termed porcine intestinal spirochetosis or spirochetal diarrhea and was characterized by end-on attachment of spirochetes to the colonic epithelium. Subsequently, other researchers have shown an association between colonization of the porcine intestinal tract with certain weakly hemolytic spirochetes and the occurrence of diarrhea (1,6,14,27,30).…”