Histologic Features Associated withTritrichomonas foetus-induced Colitis in Domestic Cats

Abstract

Abstract. Tritrichomonas foetus is a venereal pathogen of naturally bred cattle. In domestic cats, T. foetus colonizes the colon, resulting in chronic, large-bowel diarrhea. The infection is prevalent among young, densely housed cats, and there is no effective treatment. To the authors' knowledge, the characteristic microscopic lesions of T. foetus infection in naturally infected cats have not been described. The aim of the study reported here was to characterize the histologic changes in the colon of seven cats with T. foetus infection and chronic diarrhea. All cats were 1 year old or younger (mean, 6.7 6 1.7 months), and a diagnosis of T. foetus infection was made on the basis of direct fecal smear examination (five cats), fecal culture in InPouch TM TF medium (four cats), single-tube nested polymerase chain reaction (PCR) analysis of DNA extracted from feces (two cats), or observation of trichomonads in sections of colon followed by PCR confirmation on DNA extracted from paraffinembedded tissue (two cats). The presence of colonic trichomonads was the most diagnostic histologic feature. Organisms were identified in all cats, but in only 24 of 43 (56%) sections of colon. Trichomonads were generally present in close proximity to the mucosal surface and less frequently in the lumen of colonic crypts. The presence of colonic trichomonads was consistently associated with mild-to-moderate lymphoplasmacytic and neutrophilic colitis, crypt epithelial cell hypertrophy, hyperplasia and increased mitotic activity, loss of goblet cells, crypt microabscesses, and attenuation of the superficial colonic mucosa. In two of the cats, histologic lesions were more severe and were associated with invasion of trichomonads into the lamina propria and/or deeper layers of the colon.

Cysteine Protease Activity of Feline Tritrichomonas foetus Promotes Adhesion-Dependent Cytotoxicity to Intestinal Epithelial Cells

“…Using this approach, we demonstrated that T. foetus causes progressive cytotoxicity to the intestinal epithelium characterized by progressive loss of cells from the monolayer. An ongoing loss of colonic epithelial cells in vivo in cats naturally infected by T. foetus is supported by histological lesions that demonstrate attenuation of the surface epithelium in conjunction with cellular hyperplasia and hypertrophy and increased mitotic activity within the crypts (23).…”

Tritrichomonas foetus: a new cause of diarrhea in cats in Greece

“…There is no convincing evidence that reproductive tract infection plays any role in the transmission of T. foetus in cats (Gray et al 2010). T. foetus affects mainly the colonic mucosa and the mucosa of the last part of the small intestine (Gookin et al 2001, Yaeger andGookin 2005).…”

Mechanisms ofTritrichomonas foetusPathogenicity in Cats with Insights from Venereal Trichomonosis

“…These lesions, which were found to be more severe when associated with the presence of trichomonads, indicate ongoing loss of colonic epithelial cells. In severe cases, epithelial detachment and apoptosis result in loss of epithelial continuity and invasion of trichomonads into the subepithelium38 (Fig 6). Interestingly, similar subepithelial invasion of trichomonads has been described in the intestinal tract of fetuses aborted from cows infected with bovine T. foetus 81…”

“…38 The proinflammatory molecules responsible for eliciting intestinal inflammation in T. foetus infection are unknown. Immunohistochemical examination of colonic mucosa from naturally infected cats not only shows T. foetus organisms in contact with the surface epithelium but also the presence of immunoreactive T. foetus antigen within the epithelial cells and lamina propria 10, 38. Therefore, release of proinflammatory cytokines by the infected intestinal epithelial cells is suspected, but not yet conclusively identified.…”