Isolamento e identificação de Pythium Insidiosum em equinos na Baixada Maranhense

Abstract

Pythiosis is a granulomatous disease that primarily affects the cutaneous and subcutaneous tissues in domestic animals, wildlife, and humans. The present study aimed to determine the occurrence of Pythium insidiosum infection in horses, using fungal culture, isolation, and phenotypic identification in horses from the Baixada Maranhense region – MA and neighboring municipalities. Samples were collected from 23 horses showing clinical signs characteristic of pythiosis from the following municipalities in the Baixada Maranhense: Arari, Pedro do Rosário, Penalva, Pinheiro, São João Batista, São Vicente, and Viana, in addition to collections in nearby municipalities: Itapecuru-Mirim and Matões do Norte. The animals presented ulcerative lesions with a granulomatous appearance, serosanguineous exudate, and the presence of small firm yellowish granules known as kunkers. Material was obtained through tissue biopsy or fragments of kunkers, stored in sterile universal collectors with caps containing 0.9% saline solution, and transported under refrigeration to the Mycology Laboratory of UEMA. The samples were washed with antibiotic and 0.9% saline solution and inoculated onto Yeast Extract Agar, then incubated at 37ºC in an oven for two to five days. After the incubation period, seven samples presented colonies with a membranous appearance, smooth and slightly viscous texture, exhibiting a uniform cream coloration. The colonies displayed rapid growth, covering the surface of the culture medium with robust and well-defined mycelial development, forming slightly irregular and raised edges. Microscopically, the colonies revealed hyaline, aseptate or sparsely septate hyphae with a large diameter, sparsely separated, with branching at acute angles, irregular, and distinguished by the absence of transverse divisions—a typical characteristic of certain pathogenic organisms such as P. insidiosum. These results highlight the importance of early and accurate diagnosis for controlling pythiosis, a disease with a significant impact on animal health, especially in endemic regions such as the Baixada Maranhense. The identification and isolation of the pathogen in horses reinforce the need for continuous surveillance and management strategies that can mitigate the effects of this disease in affected animals