Screening of antifungal susceptibility in cave-dwelling aspergilli and report of an amphotericin B-resistant Aspergillus flavus
| Autor: | Erika L.S. Taylor, Gabriella F. Ferreira, Gustavo J.C. Freitas, Rodrigo L. Ferreira, Daniel de Assis Santos, Maria A. de Resende-Stoianoff |
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| Jazyk: | angličtina |
| Rok vydání: | 2017 |
| Předmět: | |
| Zdroj: | International Journal of Speleology, Vol 46, Iss 3, Pp 369-378 (2017) |
| Druh dokumentu: | article |
| ISSN: | 1827-806X 0392-6672 |
| DOI: | 10.5038/1827-806X.46.3.2105 |
| Popis: | Caves are stable environments that favour the development of several microorganisms. The aspergilli represent a large number of species isolated from caves including strains capable of causing serious invasive opportunistic infections in humans. Considering that caves may harbour resistant strains to many antibiotics, investigation on the response of opportunistic aspergilli, isolated from pristine and tourist caves to antifungal agents and the mechanisms involved in resistance might be clinically relevant. A total of 32 strains of the species Aspergillus candidus, A. flavus, A. fumigatus, A. niger, A. tamarii, and A. terreus were isolated from caves in the iron quadrangle in Brazil. The strains were tested for their susceptibility to amphotericin B (AMB), itraconazole, voriconazole and terbinafine. One strain was analysed for the mechanism involved in the AMB-resistance, i.e., ergosterol content, lipid peroxidation and enzymatic activity of the antioxidant system. Terbinafine minimum inhibitory concentrations (MICs) ranged between 0.003 and 1.0 µg/mL; voriconazole MICs ranged between 2.0 and >16.0 µg/mL; itraconazole MICs ranged between 0.25 and 8.0 µg/mL and amphotericin B MICs ranged between 0.03 and 4.0 µg/mL. The AMB-resistant strain of A. flavus was detected with MIC value of 4 µg/mL. Resistance to AMB relied on higher ergosterol levels and increased enzymatic activity of the peroxidase and superoxide-dismutase, with lower lipid peroxidation. These results enhance the knowledge of natural antifungal resistance in the subterranean ecosystem, and broaden the knowledge about the subterranean microbiota. |
| Databáze: | Directory of Open Access Journals |
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