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Microbial interactions have the potential to influence a patient’s diagnosis, prognosis, and therapy. Sporotrichosis, caused by Sporothrix brasiliensis, is a hyperendemic neglected zoonosis in Brazil. In a sporotrichosis hyperendemic area of Brazil, four pairs of clinical isolates of Sporothrix were obtained from four ill cats (CIM01-CIM04, two isolates per animal), highlighting the potential of coinfection. In mycological cultivation, each of the pair’s isolates had different pigmentation, and they were labelled “Light” or “Dark” for low and high pigmentation, respectively. By ELISA and FACS quantification, dark isolates responded strongly with monoclonal antibodies to melanin (p 0.05), and immunofluorescence revealed a ring pattern with certain sections having stronger punctuated staining at the cell wall. Light isolates, on the other hand, responded less strongly, with fewer and more distinct punctuated labelling at the cell wall. S. brasiliensis, MAT1-2 idiomorph, was found in all isolates by PCR. Phylogenetic analysis of the -tubulin and calmodulin genes revealed all eight isolates in the same cluster as those from the Brazilian hyperendemic region. These strains were also tested for their capacity to trigger cytokine production in human PBMCs (Peripheral blood mononuclear cells). The cytokine profiles of the CIM01 and CIM03 Light and Dark isolates were similar to the control strain, while CIM02 and CIM04 reacted differently (p 0.001), showing that variations in the isolates’ surfaces can alter host-fungus interaction. Amphotericin B, terbinafine, caspofungin, micafungin, itraconazole, fluconazole, and voriconazole MICs (CLSI M38-A2/M27-A3) were determined. To at least one of the antifungals tested, pairwise comparisons revealed different MICs between Sporothrix Light and Dark isolates, higher than at least two-fold dilutions. Isolates from the same pair showed differences in fungistatic or fungicidal pharmacological action, particularly following exposure to itraconazole. Because the phenotypic features of S. brasiliensis Light and Dark isolates differ, it’s probable that coinfection is a regular occurrence in the hyperendemic region, with clinical consequences for feline sporotrichosis dynamics. Future research will look at whether this species, like other fungus, has a wide range of phenotypic plasticity.
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