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Moreau J, Noël T, Point K, Tewes F, Deroche L, Clarhaut J, Fitton-Ouhabi V, Perraud E, Marchand S, Buyck JM, Brunet K. Pan-azole-resistant Meyerozyma guilliermondii clonal isolates harbouring a double F126L and L505F mutation in Erg11. Mycoses 2024; 67:e13704. [PMID: 38429226 DOI: 10.1111/myc.13704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 01/29/2024] [Accepted: 02/02/2024] [Indexed: 03/03/2024]
Abstract
BACKGROUND Meyerozyma guilliermondii is a yeast species responsible for invasive fungal infections. It has high minimum inhibitory concentrations (MICs) to echinocandins, the first-line treatment of candidemia. In this context, azole antifungal agents are frequently used. However, in recent years, a number of azole-resistant strains have been described. Their mechanisms of resistance are currently poorly studied. OBJECTIVE The aim of this study was consequently to understand the mechanisms of azole resistance in several clinical isolates of M. guilliermondii. METHODS Ten isolates of M. guilliermondii and the ATCC 6260 reference strain were studied. MICs of azoles were determined first. Whole genome sequencing of the isolates was then carried out and the mutations identified in ERG11 were expressed in a CTG clade yeast model (C. lusitaniae). RNA expression of ERG11, MDR1 and CDR1 was evaluated by quantitative PCR. A phylogenic analysis was developed and performed on M. guilliermondii isolates. Lastly, in vitro experiments on fitness cost and virulence were carried out. RESULTS Of the ten isolates tested, three showed pan-azole resistance. A combination of F126L and L505F mutations in Erg11 was highlighted in these three isolates. Interestingly, a combination of these two mutations was necessary to confer azole resistance. An overexpression of the Cdr1 efflux pump was also evidenced in one strain. Moreover, the three pan-azole-resistant isolates were shown to be genetically related and not associated with a fitness cost or a lower virulence, suggesting a possible clonal transmission. CONCLUSION In conclusion, this study identified an original combination of ERG11 mutations responsible for pan-azole-resistance in M. guilliermondii. Moreover, we proposed a new MLST analysis for M. guilliermondii that identified possible clonal transmission of pan-azole-resistant strains. Future studies are needed to investigate the distribution of this clone in hospital environment and should lead to the reconsideration of the treatment for this species.
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Affiliation(s)
- Jérémy Moreau
- Université de Poitiers, INSERM U1070 PHAR2, Poitiers, France
| | - Thierry Noël
- Université de Bordeaux, CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France
| | - Kévin Point
- Université de Poitiers, INSERM U1070 PHAR2, Poitiers, France
| | - Frédéric Tewes
- Université de Poitiers, INSERM U1070 PHAR2, Poitiers, France
| | - Luc Deroche
- CHU de Poitiers, Service de Virologie, Poitiers, France
| | - Jonathan Clarhaut
- Université de Poitiers, INSERM U1070 PHAR2, Poitiers, France
- CHU de Poitiers, Service de Toxicologie-Pharmacocinétique, Poitiers, France
| | - Valérie Fitton-Ouhabi
- Université de Bordeaux, CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France
| | - Estelle Perraud
- CHU de Poitiers, Service de Parasitologie et Mycologie Médicale, Poitiers, France
| | - Sandrine Marchand
- Université de Poitiers, INSERM U1070 PHAR2, Poitiers, France
- CHU de Poitiers, Service de Toxicologie-Pharmacocinétique, Poitiers, France
| | - Julien M Buyck
- Université de Poitiers, INSERM U1070 PHAR2, Poitiers, France
| | - Kévin Brunet
- Université de Poitiers, INSERM U1070 PHAR2, Poitiers, France
- CHU de Poitiers, Service de Parasitologie et Mycologie Médicale, Poitiers, France
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Ceballos-Garzon A, Peñuela A, Valderrama-Beltrán S, Vargas-Casanova Y, Ariza B, Parra-Giraldo CM. Emergence and circulation of azole-resistant C. albicans, C. auris and C. parapsilosis bloodstream isolates carrying Y132F, K143R or T220L Erg11p substitutions in Colombia. Front Cell Infect Microbiol 2023; 13:1136217. [PMID: 37026059 PMCID: PMC10070958 DOI: 10.3389/fcimb.2023.1136217] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Accepted: 03/07/2023] [Indexed: 04/08/2023] Open
Abstract
Methods Over a four-year period, 123 Candida bloodstream isolates were collected at a quaternary care hospital. The isolates were identified by MALDI-TOF MS and their fluconazole (FLC) susceptibility patterns were assessed according to CLSI guidelines. Subsequently, sequencing of ERG11, TAC1 or MRR1, and efflux pump activity were performed for resistant isolates. Results Out of 123 clinical strains,C. albicans accounted for 37.4%, followed by C. tropicalis 26.8%, C. parapsilosis 19.5%, C. auris 8.1%, C. glabrata 4.1%, C. krusei 2.4% and C. lusitaniae 1.6%. Resistance to FLC reached 18%; in addition, a high proportion of isolates were cross-resistant to voriconazole. Erg11 amino acid substitutions associated with FLC-resistance (Y132F, K143R, or T220L) were found in 11/19 (58%) of FLCresistant isolates. Furthermore, novel mutations were found in all genes evaluated. Regarding efflux pumps, 8/19 (42%) of FLC-resistant Candida spp strains showed significant efflux activity. Finally, 6/19 (31%) of FLC-resistant isolates neither harbored resistance-associated mutations nor showed efflux pump activity. Among FLC-resistant species, C. auris 7/10 (70%) and C. parapsilosis 6/24 (25%) displayed the highest percentages of resistance (C. albicans 6/46, 13%). Discussion Overall, 68% of FLC-resistant isolates exhibited a mechanism that could explain their phenotype (e.g. mutations, efflux pump activity, or both). We provide evidence that isolates from patients admitted to a Colombian hospital harbor amino acid substitutions related to resistance to one of the most commonly used molecules in the hospital setting, with Y132F being the most frequently detected.
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Affiliation(s)
- Andres Ceballos-Garzon
- Unidad de Proteomica y Micosis Humanas, Grupo de Investigación en Enfermedades Infecciosas, Departamento de Microbiología, Pontificia Universidad Javeriana, Bogotá, Colombia
| | - Ana Peñuela
- Unidad de Proteomica y Micosis Humanas, Grupo de Investigación en Enfermedades Infecciosas, Departamento de Microbiología, Pontificia Universidad Javeriana, Bogotá, Colombia
- Laboratorio Clínico, Área de Microbiología, Hospital Universitario San Ignacio, Bogotá, Colombia
| | - Sandra Valderrama-Beltrán
- Unidad de Infectología, Departamento de Medicina Interna, Facultad de Medicina, Hospital Universitario San Ignacio, Pontificia Universidad Javeriana, Bogotá, Colombia
| | - Yerly Vargas-Casanova
- Unidad de Proteomica y Micosis Humanas, Grupo de Investigación en Enfermedades Infecciosas, Departamento de Microbiología, Pontificia Universidad Javeriana, Bogotá, Colombia
| | - Beatriz Ariza
- Laboratorio Clínico, Área de Microbiología, Hospital Universitario San Ignacio, Bogotá, Colombia
| | - Claudia M. Parra-Giraldo
- Unidad de Proteomica y Micosis Humanas, Grupo de Investigación en Enfermedades Infecciosas, Departamento de Microbiología, Pontificia Universidad Javeriana, Bogotá, Colombia
- *Correspondence: Claudia M. Parra-Giraldo,
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Sitterlé E, Coste AT, Obadia T, Maufrais C, Chauvel M, Sertour N, Sanglard D, Puel A, D'Enfert C, Bougnoux ME. Large-scale genome mining allows identification of neutral polymorphisms and novel resistance mutations in genes involved in Candida albicans resistance to azoles and echinocandins. J Antimicrob Chemother 2021; 75:835-848. [PMID: 31923309 DOI: 10.1093/jac/dkz537] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 11/22/2019] [Accepted: 12/01/2019] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND The genome of Candida albicans displays significant polymorphism. Point mutations in genes involved in resistance to antifungals may either confer phenotypic resistance or be devoid of phenotypic consequences. OBJECTIVES To catalogue polymorphisms in azole and echinocandin resistance genes occurring in susceptible strains in order to rapidly pinpoint relevant mutations in resistant strains. METHODS Genome sequences from 151 unrelated C. albicans strains susceptible to fluconazole and caspofungin were used to create a catalogue of non-synonymous polymorphisms in genes involved in resistance to azoles (ERG11, TAC1, MRR1 and UPC2) or echinocandins (FKS1). The potential of this catalogue to reveal putative resistance mutations was tested in 10 azole-resistant isolates, including 1 intermediate to caspofungin. Selected mutations were analysed by mutagenesis experiments or mutational prediction effect. RESULTS In the susceptible strains, we identified 126 amino acid substitutions constituting the catalogue of phenotypically neutral polymorphisms. By excluding these neutral substitutions, we identified 22 additional substitutions in the 10 resistant strains. Among these substitutions, 10 had already been associated with resistance. The remaining 12 were in Tac1p (n = 6), Upc2p (n = 2) and Erg11p (n = 4). Four out of the six homozygous substitutions in Tac1p (H263Y, A790V, H839Y and P971S) conferred increases in azole MICs, while no effects were observed for those in Upc2p. Additionally, two homozygous substitutions (Y64H and P236S) had a predicted conformation effect on Erg11p. CONCLUSIONS By establishing a catalogue of neutral polymorphisms occurring in genes involved in resistance to antifungal drugs, we provide a useful resource for rapid identification of mutations possibly responsible for phenotypic resistance in C. albicans.
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Affiliation(s)
- Emilie Sitterlé
- Unité Biologie et Pathogénicité Fongiques, Département de Mycologie, Institut Pasteur, USC2019 INRA, Paris, France.,Université Paris Diderot, Sorbonne Paris Cité, Paris, France.,Unité de Parasitologie-Mycologie, Service de Microbiologie clinique, Hôpital Necker-Enfants-Malades, Assistance Publique des Hôpitaux de Paris (APHP), Paris, France
| | - Alix T Coste
- Institut de Microbiologie, Université de Lausanne et Centre Hospitalo-Universitaire, Lausanne, Switzerland
| | - Thomas Obadia
- Hub de Bioinformatique et Biostatistique, Département Biologie Computationnelle, Institut Pasteur, USR 3756 CNRS, Paris, France.,Unité Malaria: parasites et hôtes, Département Parasites et Insectes Vecteurs, Institut Pasteur, Paris, France
| | - Corinne Maufrais
- Hub de Bioinformatique et Biostatistique, Département Biologie Computationnelle, Institut Pasteur, USR 3756 CNRS, Paris, France
| | - Murielle Chauvel
- Unité Biologie et Pathogénicité Fongiques, Département de Mycologie, Institut Pasteur, USC2019 INRA, Paris, France
| | - Natacha Sertour
- Unité Biologie et Pathogénicité Fongiques, Département de Mycologie, Institut Pasteur, USC2019 INRA, Paris, France
| | - Dominique Sanglard
- Institut de Microbiologie, Université de Lausanne et Centre Hospitalo-Universitaire, Lausanne, Switzerland
| | - Anne Puel
- Laboratoire de génétique humaine des maladies infectieuses, Necker, INSERM U1163, Paris, France.,Université Paris Descartes, Institut Imagine, Paris, France
| | - Christophe D'Enfert
- Unité Biologie et Pathogénicité Fongiques, Département de Mycologie, Institut Pasteur, USC2019 INRA, Paris, France
| | - Marie-Elisabeth Bougnoux
- Unité Biologie et Pathogénicité Fongiques, Département de Mycologie, Institut Pasteur, USC2019 INRA, Paris, France.,Unité de Parasitologie-Mycologie, Service de Microbiologie clinique, Hôpital Necker-Enfants-Malades, Assistance Publique des Hôpitaux de Paris (APHP), Paris, France.,Université de Paris, Paris, France
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Fattouh N, Hdayed D, Geukgeuzian G, Tokajian S, Khalaf RA. Molecular mechanism of fluconazole resistance and pathogenicity attributes of Lebanese Candida albicans hospital isolates. Fungal Genet Biol 2021; 153:103575. [PMID: 34033880 DOI: 10.1016/j.fgb.2021.103575] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 04/11/2021] [Accepted: 05/14/2021] [Indexed: 12/15/2022]
Abstract
Hospital infections caused by the opportunistic fungus Candida albicans are increasingly common and life threatening. The first line of defense consists of administering antifungal drugs such as azoles including fluconazole that prevent ergosterol biosynthesis. C. albicans is rapidly developing resistance towards antifungal drugs through various mechanisms including mutations in ERG11 which is a gene involved in the ergosterol biosynthesis pathway. These mutations prevent the binding of the drug and inactivate ergosterol synthesis. Alternatively, upregulation of cell membrane ergosterol content generates resistance by countering the effect of the drug. In this study we sequenced the ERG11 gene in 6 fluconazole sensitive and 8 fluconazole resistant C. albicans isolates recovered from clinical settings in Lebanon and quantified the ergosterol content of their plasma membranes to identify mechanisms linked to fluconazole resistance. A number of pathogenicity attributes were also analyzed to determine any correlation with fluconazole resistance. Our results revealed an increase in ergosterol content in the fluconazole resistant isolates. In addition, we identified both novel and previously reported amino acid substitutions in ERG11 as well as frameshift mutations that might contribute to resistance. The fluconazole resistant isolates did not exhibit an increased virulence potential in a mouse model of systemic infection and showed decreased in vitro potential to form biofilms. No discrepancy between drug resistant and sensitive isolates to cell surface disrupting agents was observed. This approach is the first of its kind to be carried out in Lebanon to identify possible mechanisms and phenotypes of drug resistant C. albicans isolates.
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Affiliation(s)
- Nour Fattouh
- Department of Natural Sciences, Lebanese American University, PO Box 36, Byblos, Lebanon
| | - Dana Hdayed
- Department of Natural Sciences, Lebanese American University, PO Box 36, Byblos, Lebanon
| | - Geovanni Geukgeuzian
- Department of Natural Sciences, Lebanese American University, PO Box 36, Byblos, Lebanon
| | - Sima Tokajian
- Department of Natural Sciences, Lebanese American University, PO Box 36, Byblos, Lebanon
| | - Roy A Khalaf
- Department of Natural Sciences, Lebanese American University, PO Box 36, Byblos, Lebanon.
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What do we know about the biology of the emerging fungal pathogen of humans Candida auris? Microbiol Res 2020; 242:126621. [PMID: 33096325 DOI: 10.1016/j.micres.2020.126621] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 09/25/2020] [Accepted: 10/04/2020] [Indexed: 02/07/2023]
Abstract
Candida auris is a worrisome fungal pathogen of humans which emerged merely about a decade ago. Ever since then the scientific community worked hard to understand clinically relevant traits, such as virulence factors, antifungal resistance mechanisms, and its ability to adhere to human skin and medical devices. Whole-genome sequencing of clinical isolates and epidemiological studies outlining the path of nosocomial outbreaks have been the focus of research into this pathogenic and multidrug-resistant yeast since its first description in 2009. More recently, work was started by several laboratories to explore the biology of C. auris. Here, we review the insights of studies characterizing the mechanisms underpinning antifungal drug resistance, biofilm formation, morphogenetic switching, cell aggregation, virulence, and pathogenicity of C. auris. We conclude that, although some progress has been made, there is still a long journey ahead of us, before we fully understand this novel pathogen. Critically important is the development of molecular tools for C. auris to make this fungus genetically tractable and traceable. This will allow an in-depth molecular dissection of the life cycle of C. auris, of its characteristics while interacting with the human host, and the mechanisms it employs to avoid being killed by antifungals and the immune system.
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Candida glabrata Transcription Factor Rpn4 Mediates Fluconazole Resistance through Regulation of Ergosterol Biosynthesis and Plasma Membrane Permeability. Antimicrob Agents Chemother 2020; 64:AAC.00554-20. [PMID: 32571817 PMCID: PMC7449212 DOI: 10.1128/aac.00554-20] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 06/13/2020] [Indexed: 01/05/2023] Open
Abstract
The ability to acquire azole resistance is an emblematic trait of the fungal pathogen Candida glabrata. Understanding the molecular basis of azole resistance in this pathogen is crucial for designing more suitable therapeutic strategies. This study shows that the C. glabrata transcription factor (TF) CgRpn4 is a determinant of azole drug resistance. RNA sequencing during fluconazole exposure revealed that CgRpn4 regulates the expression of 212 genes, activating 80 genes and repressing, likely in an indirect fashion, 132 genes. The ability to acquire azole resistance is an emblematic trait of the fungal pathogen Candida glabrata. Understanding the molecular basis of azole resistance in this pathogen is crucial for designing more suitable therapeutic strategies. This study shows that the C. glabrata transcription factor (TF) CgRpn4 is a determinant of azole drug resistance. RNA sequencing during fluconazole exposure revealed that CgRpn4 regulates the expression of 212 genes, activating 80 genes and repressing, likely in an indirect fashion, 132 genes. Targets comprise several proteasome and ergosterol biosynthesis genes, including ERG1, ERG2, ERG3, and ERG11. The localization of CgRpn4 to the nucleus increases upon fluconazole stress. Consistent with a role in ergosterol and plasma membrane homeostasis, CgRpn4 is required for the maintenance of ergosterol levels upon fluconazole stress, which is associated with a role in the upkeep of cell permeability and decreased intracellular fluconazole accumulation. We provide evidence that CgRpn4 directly regulates ERG11 expression through the TTGCAAA binding motif, reinforcing the relevance of this regulatory network in azole resistance. In summary, CgRpn4 is a new regulator of the ergosterol biosynthesis pathway in C. glabrata, contributing to plasma membrane homeostasis and, thus, decreasing azole drug accumulation.
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Chybowska AD, Childers DS, Farrer RA. Nine Things Genomics Can Tell Us About Candida auris. Front Genet 2020; 11:351. [PMID: 32351544 PMCID: PMC7174702 DOI: 10.3389/fgene.2020.00351] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 03/23/2020] [Indexed: 12/12/2022] Open
Abstract
Candida auris is a recently emerged multidrug-resistant fungal pathogen causing severe illness in hospitalized patients. C. auris is most closely related to a few environmental or rarely observed but cosmopolitan Candida species. However, C. auris is unique in the concern it is generating among public health agencies for its rapid emergence, difficulty to treat, and the likelihood for further and more extensive outbreaks and spread. To date, five geographically distributed and genetically divergent lineages have been identified, none of which includes isolates that were collected prior to 1996. Indeed, C. auris' ecological niche(s) and emergence remain enigmatic, although a number of hypotheses have been proposed. Recent genomic and transcriptomic work has also identified a variety of gene and chromosomal features that may have conferred C. auris with several important clinical phenotypes including its drug-resistance and growth at high temperatures. In this review we discuss nine major lines of enquiry into C. auris that big-data technologies and analytical approaches are beginning to answer.
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Affiliation(s)
- Aleksandra D. Chybowska
- School of Medicine, Medical Sciences, and Nutrition, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom
| | - Delma S. Childers
- Aberdeen Fungal Group, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom
| | - Rhys A. Farrer
- Medical Research Council Centre for Medical Mycology at The University of Exeter, Exeter, United Kingdom
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Benedetti VP, Savi DC, Aluizio R, Adamoski D, Kava V, Galli-Terasawa LV, Glienke C. ERG11 gene polymorphisms and susceptibility to fluconazole in Candida isolates from diabetic and kidney transplant patients. Rev Soc Bras Med Trop 2019; 52:e20180473. [PMID: 30843968 DOI: 10.1590/0037-8682-0473-2018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Accepted: 01/25/2019] [Indexed: 11/22/2022] Open
Abstract
INTRODUCTION Candidiasis is the most frequent opportunistic mycosis in humans and can cause mortality, particularly in immunodeficient patients. One major concern is the increasing number of infections caused by drug-resistant Candidas trains, as these cannot be efficiently treated with standard therapeutics. The most common mechanism of fluconazole resistance in Candida is mutation of ERG11, a gene involved in the biosynthesis of ergosterol, a compound essential for cell integrity and membrane function. METHODS Based on this knowledge, we investigated polymorphisms in the ERG11 gene of 3 Candida species isolated from immunocompromised and immunocompetent patients. In addition, we correlated the genetic data with the fluconazole susceptibility profile of the Candida isolates. RESULTS A total of 80 Candida albicans, 8 Candida tropicalis and 6 Candida glabrata isolates were obtained from the saliva of diabetic, kidney transplant and immunocompetent patients. Isolates were considered susceptible to fluconazole if the minimum inhibitory concentration was lower than 8 μg/mL. The amino acid mutations F105L, D116E, K119N, S137L, and K128T were observed in C. albicans isolates, and T224C and G263A were found in C. tropicalis isolates. CONCLUSIONS Despite the high number of polymorphisms observed, the mutations occurred in regions that are not predicted to interfere with ergosterol synthesis, and therefore are not related to fluconazole resistance.
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Affiliation(s)
- Volmir Pitt Benedetti
- Departamento de Microbiologia da Universidade Paranaense, Francisco Beltrão, PR, Brasil.,Departamento de Patologia Básica, Universidade Federal do Paraná, Curitiba, PR, Brasil
| | | | - Rodrigo Aluizio
- Departamento de Genética, Universidade Federal do Paraná, Curitiba, PR, Brasil
| | - Douglas Adamoski
- Departamento de Genética, Universidade Federal do Paraná, Curitiba, PR, Brasil
| | - Vanessa Kava
- Departamento de Genética, Universidade Federal do Paraná, Curitiba, PR, Brasil
| | | | - Chirlei Glienke
- Departamento de Patologia Básica, Universidade Federal do Paraná, Curitiba, PR, Brasil.,Departamento de Genética, Universidade Federal do Paraná, Curitiba, PR, Brasil
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Chew KL, Cheng JW, Jureen R, Lin RT, Teo JW. ERG11 mutations are associated with high-level azole resistance in clinical Candida tropicalis isolates, a Singapore study. MYCOSCIENCE 2017. [DOI: 10.1016/j.myc.2016.11.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Aspergillus fumigatus Intrinsic Fluconazole Resistance Is Due to the Naturally Occurring T301I Substitution in Cyp51Ap. Antimicrob Agents Chemother 2016; 60:5420-6. [PMID: 27381395 DOI: 10.1128/aac.00905-16] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 06/22/2016] [Indexed: 11/20/2022] Open
Abstract
Aspergillus fumigatus intrinsic fluconazole resistance has been demonstrated to be linked to the CYP51A gene, although the precise molecular mechanism has not been elucidated yet. Comparisons between A. fumigatus Cyp51Ap and Candida albicans Erg11p sequences showed differences in amino acid residues already associated with fluconazole resistance in C. albicans The aim of this study was to analyze the role of the natural polymorphism I301 in Aspergillus fumigatus Cyp51Ap in the intrinsic fluconazole resistance phenotype of this pathogen. The I301 residue in A. fumigatus Cyp51Ap was replaced with a threonine (analogue to T315 at Candida albicans fluconazole-susceptible Erg11p) by changing one single nucleotide in the CYP51A gene. Also, a CYP51A knockout strain was obtained using the same parental strain. Both mutants' antifungal susceptibilities were tested. The I301T mutant exhibited a lower level of resistance to fluconazole (MIC, 20 μg/ml) than the parental strain (MIC, 640 μg/ml), while no changes in MIC were observed for other azole- and non-azole-based drugs. These data strongly implicate the A. fumigatus Cyp51Ap I301 residue in the intrinsic resistance to fluconazole.
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