Sporotrichosis Outbreak Due to Sporothrix brasiliensis in Domestic Cats in Magallanes, Chile: A One-Health-Approach Study

Abstract

Sporotrichosis is an implantation mycosis with subcutaneo-lymphatic or, more rarely, a viscerally disseminated affection; it can be acquired through traumatic percutaneous inoculation of the fungus present in soil or plant matter, or by feline scratching. Among the causative agents, Sporothrix brasiliensis is considered the most virulent species with a high prevalence in Brazil and recently in Argentina.

Objective: To describe a S. brasiliensis outbreak in domestic and feral cats detected in the Magallanes region of southern Chile.

Materials and methods: Between the months of July and September 2022, three cats presented with suppurative subcutaneous lesions located mainly on the head and thoracic limbs. The cytology revealed the presence of yeasts with morphological characteristics suggestive of Sporothrix spp. The histopathology confirmed pyogranulomatous subcutaneous lesions associated with the presence of the same yeasts. The fungal culture followed by the partial gene sequence and analysis of the ITS region confirmed the diagnosis of the S. brasiliensis as the causative agent. The cats were treated with itraconazole associated in one case with potassium iodide. The evolution of the patients was favorable in all cases.

Conclusions: An outbreak caused by S. brasiliensis was detected in domestic and feral cats in austral Chile. The correct identification of this fungus and antifungigram is essential for treatment decisions and for designing dissemination control and prevention programs under a one health approach that consider the health of people, animals, and the environment.

Keywords: Sporothrix brasiliensis; cats; outbreak; zoonotic disease.

Figure 1

Clinical aspect of feline sporotrichosis. (A,B) Ulcerated lesions in the cephalic region and forelimb, associated with laceration of the left ear. (D) Subcutaneous, sero-bloody erosions located on the face near the eye, with inflammation and deformation of the nasal septum. (F): Periocular lesion with a moist and scaly appearance. (C,G). Clinical appearance of the lesions after treatment (C) A remarkable clinical cure is observed after 5 months of treatment with itraconazole (G) The evolution of treatment it is favorable after two months with treatment with itraconazole. (E) Appearance of lesions after 2 months of treatment with itraconazole and potassium iodide.

Figure 2

Histological section of a skin lesion from a cat with Sporotrichosis. Hematoxylin-eosin (A–C) and Periodic acid-Shiff (D) stain. (A) Diffuse pyogranulomatous inflammation is present throughout the skin layers. (B) Multiple foci of necrosis are surrounded by numerous macrophages, intermingled with neutrophils. (C) Round to elongated yeasts 2 to 3 μm in diameter are present in profusion, both free and within the cytoplasm of macrophages. (D) Numerous yeasts with frequent budding figures can be seen, corresponding to Sporothrix spp.

Figure 3

(A) Cytologic preparation collected from an ulcerated lesion of the cat’s skin showing an intermediate epithelial cell surrounded by many yeasts, stained using the Gram and observed at 1000× magnification. (B) Macromorphology of the colonies of S. brasiliensis cultivated in SGA medium for 10 days at 25 °C (C,D) Preparation made from a microculture of a colony of S. brasiliensis grown in SGA. Septate hyaline hyphae are seen, and conidiogenous cells arise from undifferentiated hyphae, forming conidia in groups on small, clustered denticles, stained using the lactophenol cotton blue observed at 1000× magnification.