Resumo

SALAS ARAUJO, Yaritza Josefina et al. Structure and ultrastructure of Pythium insidiosum in canine gastrointestinal pythiosis. Rev. Soc. Ven. Microbiol. [online]. 2009, vol.29, n.2, pp.117-121. ISSN 1315-2556.

Pythiosis is a granulomatous disease that occurs in humans and other mammals, produced by Pythium insidiosum, a pseudofungus classified in the Straminipila kingdom. In Venezuela, pythiosis cases have been diagnosed in dogs with chronic hemorrhagic diarrhea; nevertheless, the structural and ultrastructural characteristics of the lesions have not been studied in depth. The objective set for this study was to describe, through scanning and transmission electron microscopy, the structure and ultrastructure of P. insidiosum, and the lesions it produces in the gastrointestinal tract of dogs. Tissue samples from canines with a gastrointestinal pythiosis diagnosis, referred by the Veterinary Hospital of the Universidad Centroccidental “Lisandro Alvarado”, were processed for electron microscopy study. The samples examined showed necrotic tissue, vascular thrombosis and numerous P. insidiosum hyphae, characterized by being long, ondulating, with flattened walls, 3 to 5 µm in diameter, ramified in a 90^o angle, and externally surrounded by an electron dense granular material in the form of inlays, suggestive of the Splendore-Hoeppli phenomenon. It was concluded that canine pythiosis evolves with granulomatous and thrombotic lesions, which show that the etiologic agent maintains its integrity, in spite of being intimately related with phagocytic cells.

Palavras-chave : Pythium insidiosum; gastrointestinal pythiosis; structure; ultrastructure; dogs.

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