Objective:The aim of this research was to evaluate susceptibility to antifungal agents of a environmental isolate of black yeast, obtained from samples of water. Methods:The yeast was obtained from a subtropical coastal lagoon in South America (fig 1). Identified from the D1/D2 domain of the 26S and ITS gene of the LSU rRNA, using the NL1/NL4 and ITS1/ITS4 universal primers, through the BLAST tool provided by the National Center for Biotechnology Information. The in vitro assay was performed using the microdilution technique according to protocol M27-A3 of the Clinical and Laboratory Standards Institute. The isolates were cultured on Sabouraud agar for 6 days at 30 ° C. The inoculum was prepared in a 85% saline solution. The antifungals itraconazole, voriconazole, tioconazole, terbinafine and amphotericin B were tested at a concentration ranging from 16-0.0625 μg/mL. Fluconazole was tested at a concentration ranging from 64 to 0.125 μg/mL and caspofungin at 8 to 0.015 μg/mL. The whole test was done in triplicate. Incubation was performed for 7 days at 30 ° C. MICs were visually established as wells that showed total inhibition of growth. Results: The black yeast was identified as Hortaea werneckii. The sequences obtained were compared to the sequences of the CBS 167.67 T strain available in the database GenBank. The isolate was resistant only to caspofungin (MIC ≥ 8 μg/mL) and susceptible to all the others antifungal agents tested, with the highest MICs for fluconazole (MIC ≥ 16 μg/mL), followed by amphotericin B (MIC ≥ 1 μg/mL), itraconazole, terbinafine, voriconazole and thioconazole. Conclusion: Hortaea werneckii is frequently associated with Tinea nigra disease in tropical and subtropical coastal areas which commonly affects palms of the upper and lower limbs. It is a harmless disease except when it affects immunocompromised patients. In vitro studies contribute with information to medical community referring to the ideal treatment design from the resistance profiles already published.

Antifungal agents suscetibility: profile of a tropical black yeast strain