Investigation of voriconazole heteroresistance in clinical isolates of Trichosporon asahii from a multicenter study in China

ABSTRACT Heteroresistance refers to the presence of subpopulations within seemingly homogeneous microbial cells that exhibit varying sensitivities to antifungal agents, potentially contributing to treatment failure. Our study investigated the heteroresistance levels of clinical isolates of Trichospo...

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Main Authors: Chenlu Liu, Qiaoying Gao, Yingxing Li, Jinhan Yu, Shuying Yu, Xinfei Chen, Xue Li, Yingchun Xu, Ying Zhao, Lina Guo
Format: Article
Language:English
Published: American Society for Microbiology 2025-08-01
Series:Microbiology Spectrum
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Online Access:https://journals.asm.org/doi/10.1128/spectrum.00109-25
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author Chenlu Liu
Qiaoying Gao
Yingxing Li
Jinhan Yu
Shuying Yu
Xinfei Chen
Xue Li
Yingchun Xu
Ying Zhao
Lina Guo
author_facet Chenlu Liu
Qiaoying Gao
Yingxing Li
Jinhan Yu
Shuying Yu
Xinfei Chen
Xue Li
Yingchun Xu
Ying Zhao
Lina Guo
author_sort Chenlu Liu
collection DOAJ
description ABSTRACT Heteroresistance refers to the presence of subpopulations within seemingly homogeneous microbial cells that exhibit varying sensitivities to antifungal agents, potentially contributing to treatment failure. Our study investigated the heteroresistance levels of clinical isolates of Trichosporon asahii collected from a multicenter study in China. A total of 62 isolates from 31 research centers, representing five different genotypes, were analyzed. We assessed the minimal inhibitory concentrations (MICs) of voriconazole (VRC), the level of heteroresistance to voriconazole (LHV), the strains’ capacity for adaptation to high VRC concentrations (ADP), and the stability of the heteroresistance phenomenon. The isolates had low VRC MICs (average 0.038 µg/mL), with 95.2% (59/62) classified as wild type. Heteroresistance to VRC was observed in all isolates, with an average LHV (0.25–4 µg/mL) 23 times higher than the MICs (0.012–0.19 µg/mL). Additionally, 90.3% of strains tolerated VRC concentrations at least 16 times the MICs, with heteroresistant subpopulations appearing at frequencies ranging from 0.002% to 0.830%. Furthermore, the strains rapidly adapted to elevated drug concentrations following brief exposure to VRC, with 71.0% tolerating VRC at 8 µg/mL and an average ADP value 285 times the MICs. However, the strains gradually lost this resistance when serially passaged on drug-free SDA plates, with the time required for resistance loss varying among strains. Our study is the first to reveal the presence of heteroresistance in clinical Trichosporon asahii, adding to the body of research on fungal heteroresistance and posing challenges to the clinical interpretation of MIC values for guiding treatment.IMPORTANCETrichosporon asahii has become an increasingly important fungal pathogen responsible for invasive infections in clinical settings. Due to its natural resistance to flucytosine and echinocandin classes, azole drugs, especially voriconazole, are the mainstay of treatment. The phenomenon of heteroresistance may be associated with treatment failure in fungal infections; however, this phenomenon remains unclear in T. asahii. Our study provides the first comprehensive characterization of voriconazole heteroresistance in T. asahii, significantly advancing our understanding of antifungal resistance dynamics in this emerging pathogen. Our findings also challenge the reliability of conventional minimal inhibitory concentration-based therapeutic guidance for T. asahii infections.
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spelling doaj-art-c103fab50b6b4f6bb26965ac93e262ca2025-08-20T03:39:28ZengAmerican Society for MicrobiologyMicrobiology Spectrum2165-04972025-08-0113810.1128/spectrum.00109-25Investigation of voriconazole heteroresistance in clinical isolates of Trichosporon asahii from a multicenter study in ChinaChenlu Liu0Qiaoying Gao1Yingxing Li2Jinhan Yu3Shuying Yu4Xinfei Chen5Xue Li6Yingchun Xu7Ying Zhao8Lina Guo9Department of Laboratory Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, ChinaDepartment of Laboratory Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, ChinaDepartment of Laboratory Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, ChinaDepartment of Laboratory Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, ChinaDepartment of Laboratory Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, ChinaDepartment of Laboratory Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, ChinaDepartment of Laboratory Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, ChinaDepartment of Laboratory Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, ChinaDepartment of Laboratory Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, ChinaDepartment of Laboratory Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, ChinaABSTRACT Heteroresistance refers to the presence of subpopulations within seemingly homogeneous microbial cells that exhibit varying sensitivities to antifungal agents, potentially contributing to treatment failure. Our study investigated the heteroresistance levels of clinical isolates of Trichosporon asahii collected from a multicenter study in China. A total of 62 isolates from 31 research centers, representing five different genotypes, were analyzed. We assessed the minimal inhibitory concentrations (MICs) of voriconazole (VRC), the level of heteroresistance to voriconazole (LHV), the strains’ capacity for adaptation to high VRC concentrations (ADP), and the stability of the heteroresistance phenomenon. The isolates had low VRC MICs (average 0.038 µg/mL), with 95.2% (59/62) classified as wild type. Heteroresistance to VRC was observed in all isolates, with an average LHV (0.25–4 µg/mL) 23 times higher than the MICs (0.012–0.19 µg/mL). Additionally, 90.3% of strains tolerated VRC concentrations at least 16 times the MICs, with heteroresistant subpopulations appearing at frequencies ranging from 0.002% to 0.830%. Furthermore, the strains rapidly adapted to elevated drug concentrations following brief exposure to VRC, with 71.0% tolerating VRC at 8 µg/mL and an average ADP value 285 times the MICs. However, the strains gradually lost this resistance when serially passaged on drug-free SDA plates, with the time required for resistance loss varying among strains. Our study is the first to reveal the presence of heteroresistance in clinical Trichosporon asahii, adding to the body of research on fungal heteroresistance and posing challenges to the clinical interpretation of MIC values for guiding treatment.IMPORTANCETrichosporon asahii has become an increasingly important fungal pathogen responsible for invasive infections in clinical settings. Due to its natural resistance to flucytosine and echinocandin classes, azole drugs, especially voriconazole, are the mainstay of treatment. The phenomenon of heteroresistance may be associated with treatment failure in fungal infections; however, this phenomenon remains unclear in T. asahii. Our study provides the first comprehensive characterization of voriconazole heteroresistance in T. asahii, significantly advancing our understanding of antifungal resistance dynamics in this emerging pathogen. Our findings also challenge the reliability of conventional minimal inhibitory concentration-based therapeutic guidance for T. asahii infections.https://journals.asm.org/doi/10.1128/spectrum.00109-25Trichosporon asahiiheteroresistancevoriconazolesusceptibilitycross-resistance
spellingShingle Chenlu Liu
Qiaoying Gao
Yingxing Li
Jinhan Yu
Shuying Yu
Xinfei Chen
Xue Li
Yingchun Xu
Ying Zhao
Lina Guo
Investigation of voriconazole heteroresistance in clinical isolates of Trichosporon asahii from a multicenter study in China
Microbiology Spectrum
Trichosporon asahii
heteroresistance
voriconazole
susceptibility
cross-resistance
title Investigation of voriconazole heteroresistance in clinical isolates of Trichosporon asahii from a multicenter study in China
title_full Investigation of voriconazole heteroresistance in clinical isolates of Trichosporon asahii from a multicenter study in China
title_fullStr Investigation of voriconazole heteroresistance in clinical isolates of Trichosporon asahii from a multicenter study in China
title_full_unstemmed Investigation of voriconazole heteroresistance in clinical isolates of Trichosporon asahii from a multicenter study in China
title_short Investigation of voriconazole heteroresistance in clinical isolates of Trichosporon asahii from a multicenter study in China
title_sort investigation of voriconazole heteroresistance in clinical isolates of trichosporon asahii from a multicenter study in china
topic Trichosporon asahii
heteroresistance
voriconazole
susceptibility
cross-resistance
url https://journals.asm.org/doi/10.1128/spectrum.00109-25
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