Abstract
BACKGROUNDSporotrichosis is a subcutaneous mycosis caused by dimorphic pathogenic fungi belonging to the Sporothrix genus. Pathogenic Sporothrix species typically produce melanin, which is known to be a virulence factor.OBJECTIVES The aim of this study was to perform phenotypic, genotypic, and virulence analyses of two distinct Sporothrix brasiliensis strains isolated from the same lesion on a patient from Rio de Janeiro.METHODS AND FINDINGS Genotypic analyses by partial sequencing of the calmodulin, β-tubulin, and chitin synthase genes, as well as polymerase chain reaction (PCR)-fingerprinting by T3B, M13, and GACA, showed that the isolates were very similar but not identical. Both isolates had similar phenotypic characteristics and effectively produced melanin in their yeast forms, accounting for their ability of causing disease in a murine sporotrichosis model. Remarkably, isolate B was albino in its environmental form but caused more severe disease than the pigmented A isolate.CONCLUSIONS These findings indicate that the patient was infected by two genetically and biologically distinct S. brasiliensis that vary in their production of melanin in their environmental forms. The results underscore the importance of characterizing phenotypically different isolates found in the same clinical specimen or patient.
Highlights
Sporotrichosis is a subcutaneous mycosis caused by dimorphic pathogenic fungi belonging to the Sporothrix genus
S. schenckii sensu lato can synthesize three different types of melanin, both in the yeast and mycelial forms in vitro.[8] yeast cells in the infected tissues are melanized, suggesting that melanin participates in fungus-host interactions.[9] melanin protects diverse fungi from the immune defence of the host.[10]. Fungal melanins are complex polymers with covalently linked aromatic subunits that are produced by different synthetic pathways, known as the 1,8-dihydroxynaphthalene (DHN), dihydroxyphenylalanine, and L-tyrosine pathways depending on the species.[11]. Melanin functions in Sporothrix spp. include protection against oxygen and nitrogen free radicals, resistance against UV light and antifungal drugs, such as amphotericin B and terbinafine and evasion from macrophages.[12,13]
Since 1998, the metropolitan Rio de Janeiro area in Brazil has been considered an endemic region for zoonotic sporotrichosis.[14]. Infected cats may carry Sporothrix yeast cells on their nails and in the oral cavity
Summary
The aim of this study was to perform phenotypic, genotypic, and virulence analyses of two distinct Sporothrix brasiliensis strains isolated from the same lesion on a patient from Rio de Janeiro
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