Suchergebnisse

The number of invasive infections caused by Candida species is increasing worldwide. The incidence of candidiasis cases caused by non-albicans Candida species, such as Candida parapsilosis, is also increasing, and non-albicans Candida species are currently responsible for more invasive infections than C. albicans. Additionally, while the development of azole resistance during invasive disease with C. albicans remains uncommon, azole-resistant C. parapsilosis strains are frequently isolated in the hospital setting. In this study, we applied direct selection to generate azole-adapted and azole-evolved C. parapsilosis strains in order to examine the effect of azole resistance development on fungal viability and pathogenesis progression. Depending on the drug applied, the different evolved strains developed distinct cross-resistance patterns: the fluconazole-evolved (FLUEVO) and voriconazole-evolved (VOREVO) strains gained resistance to fluconazole and voriconazole only, while posaconazole evolution resulted in cross-resistance to all azoles and the posaconazole-evolved (POSEVO) strains showed higher echinocandin MIC values than the FLUEVO and VOREVO strains. Whole-genome sequencing results identified the development of different resistance mechanisms in the evolved strains: the FLUEVO and VOREVO strains harbored amino acid substitutions in Mrr1p (A808T and N394Y, respectively), and the POSEVO strain harbored an amino acid change in Erg3p (D14Y). By revealing increased efflux pump activity in both the FLUEVO and the VOREVO strains, along with the altered sterol composition of the POSEVO strain, we now highlight the impact of the above-mentioned amino acid changes in C. parapsilosis azole resistance development. We further revealed that the virulence of this species was only slightly or partially affected by fluconazole and voriconazole adaptation, while it significantly decreased after posaconazole adaptation. Our results suggest that triazole adaptation can result in azole cross-resistance and that this process may also result in virulence alterations in C. parapsilosis, depending on the applied drug. ; László Bodai was supported by a János Bolyai research scholarship (scholarship BO/00522/19/8) of the Hungarian Academy of Sciences. Attila Gácser was supported by grants 20391 3/2018/FEKUSTRAT, NKFIH K 123952, and GINOP-2.3.2.-15-2016-00035. Attila Gácser was additionally funded by grant LP2018-15/2018. Toni Gabaldón was supported by grants from the Spanish Ministry of Science and Innovation (grant PGC2018-099921-B-I00), cofounded by the European Regional Development Fund (ERDF); from the CERCA Program/Generalitat de Catalunya; from the Catalan Research Agency (grants AGAUR and SGR423); from the European Union's Horizon 2020 Research and Innovation Program (grant ERC-2016-724173); and from the Instituto Carlos III and Instituto Nacional de Bioinformática (grant PT17/0009/0023-ISCIII-SGEFI/ERDF). ; Peer Reviewed ; "Article signat per 12 autors/es: Csaba Papp, Flóra Bohner, Katica Kocsis, Mónika Varga, András Szekeres, László Bodai, Jesse R. Willis, Toni Gabaldón, Renáta Tóth, Joshua D. Nosanchuk, Csaba Vágvölgyi, and Attila Gácser" ; Postprint (published version)

Aflatoxins are mycotoxins that are produced by several species of filamentous fungi. In the European Union, the concentration limits for this group of mycotoxins in food and feed products are very low (on the order of parts per billion). Thus, relatively high amounts of these substances in their pure forms are required as reference standards. Chromatographic techniques based on solid stationary phases are generally used to purify these molecules; however, liquid–liquid chromatographic separations may be a promising alternative. Therefore, this study proposes a liquid–liquid chromatographic method for the separation of four aflatoxins and impurities. To optimise the method, numerous biphasic solvent systems (chloroform-, acetone- and acetic acid-based systems) were tested and evaluated in terms of their effectiveness at partitioning aflatoxins; the toluene/acetic acid/water (30:24:50, v/v/v/%) system was found to be the most efficient for application in centrifugal partition chromatographic instrument. Using liquid–liquid instrumental separation, the four aflatoxins, namely B(1) (400 mg), B(2) (34 mg), G(1) (817 mg) and G(2) (100 mg), were successfully isolated with 96.3%–98.2% purity from 4.5 L of Aspergillus parasiticus fermented material in a 250 mL centrifugal partition chromatography column. The identities and purities of the purified components were confirmed, and the performance parameters of each separation step and the whole procedure was determined. The developed method could be effectively used to purify aflatoxins for analytical applications.