Feline sporotrichosis: a case series of itraconazole-resistant Sporothrix brasiliensis infection

The treatment of feline sporotrichosis is a challenge for veterinary clinicians since refractory cases may occur, due either to patient and/or to pharmacological management errors or due to the development of antifungal resistance. Thus, we aimed to describe the therapeutic history of feline cases infected by itraconazole-resistant Sporothrix brasiliensis in an endemic region of Southern Brazil. Medical records of cats attended at the Veterinary Clinic Hospital (Pelotas/RS, Brazil) between 2016 and 2017 were reviewed. Twelve cases of infection by S. brasiliensis with that showed high minimum inhibitory concentration (MIC) values (≥ 4 μg/mL) to itraconazole by M38-A2 of CLSI were selected. At the hospital consultation, disseminated (cats 1–l0, 12) and localized (cat 11) skin lesions remained in the cats, even after treatment with fluconazole, ketoconazole (02/12), and itraconazole (ITZ, 09/12) performed before this study. High doses (25–100 mg/kg/day) of ITZ for up to 4 months (03/12, cats 2, 6, 12) or over 12 months (05/12, cats 1, 5, 7, 8, 11) did not provide a clinical cure, except for the association of ITZ plus potassium iodide (01/12, cat 12) for 3 months, which proved useful in infections with itraconazole-resistant S. brasiliensis . However, the combined issues of abandonment of therapy by owners for financial reasons, difficulties surrounding therapy administration (03/12, cats 6, 11, 12), and the inappropriate choice of medication (01/12, cat 6), together reflect the reality of this endemic region, which greatly compromises clinical healing. This study highlighted the occurrence of refractory cases by itraconazole-resistant S. brasiliensis in cats from Southern Brazil, as well as the abandonment of treatment and therapeutic errors. We warn of the need for antifungal susceptibility tests to adapt therapeutic protocols in feline sporotrichosis.