There have been several recent changes in the taxonomy of Sporothrix schenckii as well as new observations regarding the clinical aspects of sporotrichosis. In this study, we determined the identification of the Sporothrix species associated with both classic and unusual clinical aspects of sporotrichosis observed in the endemic area of sporotrichosis in Rio de Janeiro, Brazil. To verify whether S. brasiliensis is associated with clinical manifestations of sporotrichosis, a cross-sectional study was performed in which Sporothrix isolates from 50 patients with different clinical manifestations were analyzed and their isolates were studied by phenotypic and genotypic methods. Data from these patients revealed a distinct clinical picture and therapeutic response in infections caused by Sporothrix brasiliensis (n = 45) compared to patients with S. schenckii sensu stricto (n = 5). S. brasiliensis was associated with disseminated cutaneous infection without underlying disease, hypersensitivity reactions, and mucosal infection, whereas patients with S. schenckii presented with less severe and more often localized disease, similar to the majority of previously described sporotrichosis cases. Interestingly, S. brasiliensis-infected patients overall required shorter durations of itraconazole (median 16 weeks) compared to the individuals with S. schenckii (median 24 weeks). These findings suggest that Sporothrix species are linked to different clinical manifestations of sporotrichosis and that S. brasiliensis is effectively treated with oral itraconazole. Sporothrix brasiliensis is a dimorphic fungus that is responsible for an ongoing epidemic of cat-transmitted sporotrichosis in Rio de Janeiro, Brazil. More than 4,100 human cases have been diagnosed in only one health institution since 1998. Most patients are children or housewives with frequent contact with domestic and/or stray cats. The patients usually live under poverty conditions in suburban regions of the metropolitan area with poor access to health care and unsanitary living conditions. For instance, most patients report that they need to have cats in their houses as a control against invasion by rodents. It is important to study the clinical aspects of S. brasiliensis infection in order to improve patient management, including optimizing therapeutic and prophylactic approaches. We have found that S. brasiliensis is responsible for some unusual clinical manifestations of sporotrichosis, such as disseminated infection in immunocompetent patients and hypersensitivity reactions. Also, treatment with itraconazole appears to be extremely effective in most cases of infection by S. brasiliensis. Our study will contribute for the management of the infection caused by S. brasiliensis, bringing benefits to the patients with sporotrichosis.

TheSporothrixcomplex members cause sporotrichosis, a subcutaneous mycosis with a wide spectrum of clinical manifestations. Several specific phenotypic characteristics are associated with virulence in many fungi, but studies in this field involving theSporothrixcomplex species are scarce. Melanization, thermotolerance, and production of proteases, catalase, and urease were investigated in 61S. brasiliensis, oneS. globosa, and 10S. schenckiistrains. TheS. brasiliensisstrains showed a higher expression of melanin and urease compared withS. schenckii. These two species, however, presented similar thermotolerances. OurS. globosastrain had low expression of all studied virulence factors. The relationship between these phenotypes and clinical aspects of sporotrichosis was also evaluated. Strains isolated from patients with spontaneous regression of infection were heavily melanized and produced high urease levels. Melanin was also related to dissemination of internal organs and protease production was associated with HIV-coinfection. A murine sporotrichosis model showed that aS. brasiliensisstrain with high expression of virulence factors was able to disseminate and yield a high fungal burden in comparison with a controlS. schenckiistrain. Our results show that virulence-related phenotypes are variably expressed within theSporothrixcomplex species and might be involved in clinical aspects of sporotrichosis.

Clinical and Laboratory Standards Institute (CLSI) conditions for testing the susceptibilities of pathogenicSporothrixspecies to antifungal agents are based on a collaborative study that evaluated five clinically relevant isolates ofSporothrix schenckii sensu latoand some antifungal agents. With the advent of molecular identification, there are two basic needs: to confirm the suitability of these testing conditions for all agents andSporothrixspecies and to establish species-specific epidemiologic cutoff values (ECVs) or breakpoints (BPs) for the species. We collected available CLSI MICs/minimal effective concentrations (MECs) of amphotericin B, five triazoles, terbinafine, flucytosine, and caspofungin for 301Sporothrix schenckii sensu stricto, 486S. brasiliensis, 75S. globosa, and 13S. mexicanamolecularly identified isolates. Data were obtained in 17 independent laboratories (Australia, Europe, India, South Africa, and South and North America) using conidial inoculum suspensions and 48 to 72 h of incubation at 35°C. Sufficient and suitable data (modal MICs within 2-fold concentrations) allowed the proposal of the following ECVs forS. schenckiiandS. brasiliensis, respectively: amphotericin B, 4 and 4 μg/ml; itraconazole, 2 and 2 μg/ml; posaconazole, 2 and 2 μg/ml; and voriconazole, 64 and 32 μg/ml. Ketoconazole and terbinafine ECVs forS. brasiliensiswere 2 and 0.12 μg/ml, respectively. Insufficient or unsuitable data precluded the calculation of ketoconazole and terbinafine (or any other antifungal agent) ECVs forS. schenckii, as well as ECVs forS. globosaandS. mexicana. These ECVs could aid the clinician in identifying potentially resistant isolates (non-wild type) less likely to respond to therapy.

Terbinafine is a recommended therapeutic alternative for patients with sporotrichosis who cannot use itraconazole due to drug interactions or side effects. Melanins are involved in resistance to antifungal drugs and Sporothrix species produce three different types of melanin. Therefore, in this study we evaluated whether Sporothrix melanins impact the efficacy of antifungal drugs. Minimal inhibitory concentrations (MIC) and minimal fungicidal concentrations (MFC) of two Sporothrix brasiliensis and four Sporothrix schenckii strains grown in the presence of the melanin precursors L-DOPA and L-tyrosine were similar to the MIC determined by the CLSI standard protocol for S. schenckii susceptibility to amphotericin B, ketoconazole, itraconazole or terbinafine. When MICs were determined in the presence of inhibitors to three pathways of melanin synthesis, we observed, in four strains, an increase in terbinafine susceptibility in the presence of tricyclazole, a DHN-melanin inhibitor. In addition, one S. schenckii strain grown in the presence of L-DOPA had a higher MFC value when compared to the control. Growth curves in presence of 2×MIC concentrations of terbinafine showed that pyomelanin and, to a lesser extent, eumelanin were able to protect the fungi against the fungicidal effect of this antifungal drug. Our results suggest that melanin protects the major pathogenic species of the Sporothrix complex from the effects of terbinafine and that the development of new antifungal drugs targeting melanin synthesis may improve sporotrichosis therapies.