Phylogenetic analysis of Sporothrix brasiliensis isolated from feline sporotrichosis on São Luís Island, Maranhão, Brazil

Abstract

Sporotrichosis is a zoonotic cutaneous mycosis caused by saprophytic fungi of the Sporothrix, affecting cats, horses, dogs, and humans. This study aimed to evaluate sporotrichosis in cats clinically and to phenotypically characterize and molecularly characterize Sporothrix species on São Luís Island, Maranhão, Brazil. From October 2022 to July 2023, clinical assessments and cytological examinations were performed on suspected feline sporotrichosis cases at the Francisco Edilberto Uchôa Lopes Veterinary Hospital, State University of Maranhão. Lesion exudates were collected via exfoliation or imprinting for fungal culture and species identification. Fungal cultures underwent species-specific polymerase chain reaction (PCR), genetic sequencing, and phylogenetic analysis. A total of 46 cats (33 males and 13 females) were assessed. Disseminated cutaneous sporotrichosis was observed in 70% of cases, with lesions predominantly on the face, ears, thoracic regions, and limbs. Initially, white fungal cultures gradually turned blackish with a coriaceous texture characteristic of Sporothrix spp. PCR amplification of the calmodulin (CAL) gene using Sporothrix brasiliensis-specific primers confirmed all 46 samples as S. brasiliensis. Phylogenetic analysis revealed genetic identity rates ranging from 90% to 100% with S. brasiliensis sequences. This seems to be the first molecular confirmation of S. brasiliensis causing feline sporotrichosis on São Luís Island.