Key words: Sporothrix species; sporotrichosis; cats; phenotypic characterisation; molecular characterisation

Feline sporotrichosis is enzootic in different regions of Brazil, especially in Rio de Janeiro. This study compared the genotype profiles of Sporothrix sp. isolated from cats in Rio de Janeiro between 1998 and 2018 and evaluated their association with clinical and epidemiological characteristics. One hundred nineteen Sporothrix sp. isolates from a cohort of cats with sporotrichosis seen at INI/Fiocruz were included. Clinical and epidemiological data were obtained from the medical records of the animals. T3B PCR fingerprinting was used for molecular identification of the Sporothrix species. All isolates were characterized as Sporothrix brasiliensis, with the observation of low intraspecific variation in 31 isolates (31.3%). The interval between lesion onset and first medical visit at INI/Fiocruz, as well as treatment duration until clinical cure, was longer in cats from the first decade of the epizootic. In addition, the frequency of the variables “good general status” and “presence of lymphadenomegaly” was higher among cats whose strains did not exhibit intraspecific variation. So far, S. brasiliensis has been the only species identified in feline cases of sporotrichosis since the beginning of the epizootic in Rio de Janeiro at INI/Fiocruz.

Sporotrichosis is a subcutaneous mycosis with worldwide distribution and caused by eight pathogenic species of the Sporothrix genus. Different ex situ preservation methods are used around the world to maintain the survival, morphophysiological and genetic traits of fungal strains isolated from patients with sporotrichosis for long terms. The main aim of the present study was to evaluate the survival, phenotypic and genotypic stability of Sporothrix strains after preservation on PDA slant stored at 4 °C, sterile water and cryopreservation at −80 °C, for a period of time of 6, 12, 18 and 24 months of storage. Eight clinical Sporothrix isolates were identified based on a polyphasic approach consisting of classical macro- and micro-morphological traits, biochemical assays, proteomic profiles by MALDI-TOF MS and molecular biology. According to the final identification, one strain was identified as S. schenckii (CMRVS 40428) and seven strains were re-identified as S. brasiliensis (CMRVS 40421, CMRVS 40423, CMRVS 40424, CMRVS 40425, CMRVS 40426, CMRVS 40427 and CMRVS 40433). In addition, it was observed that the isolates survived after the different time points of storage in distilled water, PDA slant and cryopreservation at −80 °C. For fungi preserved in water, low polymorphisms were detected by the partial sequencing of β-tubulin. Cryopreservation at −80 °C induced morphological changes in one single isolate. The proteomic profiles obtained by MALDI-TOF MS after preservation showed differences among the methods. In conclusion, preservation on agar slant stored at 4 °C was the most effective method to preserve the eight clinical Sporothrix strains. This method produced less change in the phenotypic traits and kept the genetic integrity of all strains. Agar slant stored at 4 °C is a simple and inexpensive method and can be especially used in culture collections of limited funding and resources.

Brazil is an endemic region for both human and feline sporotrichosis, with Sporothrix brasiliensis being the main etiological agent. Currently, few effective antifungal agents are available for treating this mycosis in cats, and therapeutic studies remain limited. Itraconazole (ITZ) is the first-line drug; however, its effectiveness is variable. To evaluate the use of ITZ combined with β-glucans (Euglena gracilis) in feline sporotrichosis, a prospective, uncontrolled interventional study was conducted in 29 cats. Clinical cure was achieved in 21 animals (72.4%) with a median treatment duration of 10 weeks. Most of these cats presented with nasal region lesions, nasal mucosa involvement, and respiratory signs, which are commonly associated with poor therapeutic outcomes. Treatment failure occurred in 5 animals (17.2%), and 3 (10.3%) were lost to follow-up. No deaths were recorded during the study. Adverse drug reactions (ADRs) were observed in 2 cats (6.9%). These findings suggest that β-glucans may be a complementary strategy in the treatment of feline sporotrichosis, particularly in cases involving nasal lesions and respiratory signs, and may also contribute to the prevention of ADRs associated with conventional therapy.

Itraconazole (ITZ) is the most used drug to treat feline sporotrichosis; however, little is known about its pharmacokinetics in cats with this mycosis. The aim of this study was to determine plasma ITZ concentrations in cats with sporotrichosis treated with ITZ as monotherapy or in combination with potassium iodide (KI). Cats diagnosed with sporotrichosis received orally ITZ (100 mg/cat/day) or combination therapy with ITZ (100 mg/cat/day) and KI (2.5-5 mg/kg/day) in the case of worsening or stagnation of the clinical condition. At each monthly visit, blood samples were collected at an interval of 4 h for analysis of trough and peak plasma ITZ concentrations by HPLC. Clinical features and laboratory parameters were evaluated during follow-up. Sixteen cats were included in the study. The median plasma ITZ concentration of all cats was 0.75 µg/mL. The median plasma ITZ concentration was 0.5 µg/mL in cats that received ITZ monotherapy (n=12) and 1.0 µg/mL in those treated with ITZ+KI (n=4). The clinical cure rate was 56.3% (n=9) and the median treatment duration was 8 weeks. Nine cats (56.3%) developed adverse clinical reactions and hyporexia was the most frequent (n=8; 88.9%). Serum alanine aminotransferase was elevated in four cats (25%). The median plasma ITZ concentration detected in cats was considered to be therapeutic (>0.5 µg/mL) and was reached after 4 weeks of treatment. Plasma ITZ concentrations were higher in cats that received ITZ+KI compared to those treated only with ITZ, suggesting pharmacokinetic synergism between these drugs. Itraconazole is the most common therapy for feline sporotrichosis and combination therapy with potassium iodide is used in cases non-responsive. Our study showed that all cats achieved a therapeutic plasma concentration of itraconazole, with higher levels in cats treated with the combination therapy.