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Antifungal activity of selected Malassezia indolic compounds detected in culture
Author(s) -
Gaitanis Georgios,
Magiatis Prokopios,
Mexia Nikitia,
Melliou Eleni,
Efstratiou Maria A.,
Bassukas Ioannis D.,
Velegraki Aristea
Publication year - 2019
Publication title -
mycoses
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.13
H-Index - 69
eISSN - 1439-0507
pISSN - 0933-7407
DOI - 10.1111/myc.12893
Subject(s) - malassezia , microbiology and biotechnology , minimum inhibitory concentration , cryptococcus neoformans , cryptococcus , agar , biology , aspergillus flavus , yeast , fungi imperfecti , aspergillus fumigatus , aspergillus , chemistry , antimicrobial , bacteria , biochemistry , genetics
Summary Background Malassezia yeasts produce bioactive indolic substances when grown on L‐tryptophan agar. A panel of these substances was tested against commensal and opportunistic fungi, the Minimum Inhibitory Concentration ( MIC ) was determined and the potential for in loco antifungal activity on the skin was assessed. Materials and Methods Eight indoles were included (malassezin, pityriacitrin, indirubin, indolo[3,2‐b]carbazole, 6‐formylindolo[3,2‐b]carbazole, tryptanthrin, 6‐hydroxymethylindolo[3,2‐b]carbazole and 6‐methylindolo[3,2‐b]carbazole) and were tested against 40 fungal strains [yeasts: Malassezia spp.(N = 9); Cryptococcus spp.(N = 10); Candida spp.(N = 7); Yarrowia lipolytica (N = 1); Exophialla dermatitidis (N = 2); moulds: Aspergillus spp.(N = 7); Fusarium spp.(N = 2); Rhizopus oryzae (N = 2)]. The concentration of 5/8 of the tested indoles on diseased skin was calculated from published data. Kruskal‐Wallis and Mann‐Whitney U tests were employed for group susceptibility evaluation in 33 strains. Results The MIC range was 0.125‐32 μg/mL, and the median log 2 MIC was four. Indirubin was the most potent antifungal agent and differed significantly from the others. The highest median MIC was found for FICZ . Malassezia with Candida strains were more susceptible compared to Cryptococcus and Aspergillus, and this inhibitory activity was predicted to be valid also on human skin. Conclusions Malassezia yeasts produce indolic species that inhibit an array of clinically significant yeasts and moulds.