Abstract
Introduction: Dimorphic fungi of the Sporothrix schenckii complex are the aetiological agent of sporotrichosis in humans and animals. Cats in particular have gained importance in transmission of the disease to humans. Therefore, it is crucial to identify unusual aetiological agents and the varying clinical appearances of the disease. Case presentation: We describe the case of a 10-year-old cat with a 2-month history of nasal discharge after a fight with another cat. Severe thrombocytopenia was diagnosed, whilst routine testing for feline leukemia virus (FeLV) was negative. A computed tomography scan revealed profound destruction of several parts of the nasal cavity. Histological and cytological examination of biopsies taken from these locations showed a chronic pyogranulomatous inflammation with several yeast-like structures. Mycological cultivation at 28 and 37 °C yielded fungal growth with smooth to wrinkled colonies consisting of hyphae and non-pigmented sympodial, round to oval-shaped conidia. Molecular typing, including sequence analysis of the ITS region, resulted in a consensus sequence which allowed classification of the fungus into the Sporothrix schenckii complex. Although the thrombocytopenia persisted, treatment with itraconazole dissolved any respiratory symptoms and improved the clinical status of the cat, indicating an antimycotic-responsive infection. Conclusion: Amelanotic members of the Sporothrix schenckii complex should be considered a putative aetiologic agent in the pathogenesis of feline sporotrichosis in Germany. Besides being classified in close proximity to species in the environmental clade this isolate has proven to cause serious infection implying a possible zoonotic potential.
Highlights
Dimorphic fungi of the Sporothrix schenckii complex are the aetiological agent of sporotrichosis in humans and animals
Sporothrix schenckii is a dimorphic fungus well known as the causative agent of sporotrichosis in humans and animals
One of the crucial pathogenic mechanisms of dimorphic fungi is their ability to change from a mycelial form at temperatures lower than 30 uC into a thermotolerant phase with yeast-like structures, which are capable of causing fixed cutaneous or occasionally systemic disease after infecting a host via wounds or scratches (Rodrigues et al, 2013a; Welsh, 2003)
Summary
Sporothrix schenckii is a dimorphic fungus well known as the causative agent of sporotrichosis in humans and animals. Except for S. mexicana, the four other species of the complex have been isolated primarily from clinical cases and differ from environmental strains with a low potential to cause infection in mammals, such as Sporothrix pallida and Sporothrix stylites (Rodrigues et al, 2013b; Zhou et al, 2013). Colonies at 37 uC maintained their smooth character on BHI plates but got a wrinkled surface on Kimmig and Dixon agar (Fig. 2g, h) In these plates yeast-like structures dominated but were mixed with septate hyphae. Control examinations were performed after 10 days, 15 days and 5 months During this period, the thrombocytopenia persisted, with platelet counts ranging between 20000 and 55000 l21, whereas respiratory symptoms and nasal discharge improved remarkably after 3 weeks and disappeared completely after 6 weeks. The computed tomography scan revealed no further destruction of the nasal cavity
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