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Fattouh N, Husni R, Finianos M, Bitar I, Khalaf RA. Adhesive and biofilm-forming Candida glabrata Lebanese hospital isolates harbour mutations in subtelomeric silencers and adhesins. Mycoses 2024; 67:e13750. [PMID: 38813959 DOI: 10.1111/myc.13750] [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: 01/08/2024] [Revised: 05/15/2024] [Accepted: 05/20/2024] [Indexed: 05/31/2024]
Abstract
BACKGROUND The prevalence of Candida glabrata healthcare-associated infections is on the rise worldwide and in Lebanon, Candida glabrata infections are difficult to treat as a result of their resistance to azole antifungals and their ability to form biofilms. OBJECTIVES The first objective of this study was to quantify biofilm biomass in the most virulent C. glabrata isolates detected in a Lebanese hospital. In addition, other pathogenicity attributes were evaluated. The second objective was to identify the mechanisms of azole resistance in those isolates. METHODS A mouse model of disseminated systemic infection was developed to evaluate the degree of virulence of 41 azole-resistant C. glabrata collected from a Lebanese hospital. The most virulent isolates were further evaluated alongside an isolate having attenuated virulence and a reference strain for comparative purposes. A DNA-sequencing approach was adopted to detect single nucleotide polymorphisms (SNPs) leading to amino acid changes in proteins involved in azole resistance and biofilm formation. This genomic approach was supported by several phenotypic assays. RESULTS All chosen virulent isolates exhibited increased adhesion and biofilm biomass compared to the isolate having attenuated virulence. The amino acid substitutions D679E and I739N detected in the subtelomeric silencer Sir3 are potentially involved- in increased adhesion. In all isolates, amino acid substitutions were detected in the ATP-binding cassette transporters Cdr1 and Pdh1 and their transcriptional regulator Pdr1. CONCLUSIONS In summary, increased adhesion led to stable biofilm formation since mutated Sir3 could de-repress adhesins, while decreased azole susceptibility could result from mutations in Cdr1, Pdh1 and Pdr1.
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Affiliation(s)
- Nour Fattouh
- Department of Natural Sciences, Lebanese American University, Byblos, Lebanon
- Department of Biology, Saint George University of Beirut, Beirut, Lebanon
| | - Rola Husni
- School of Medicine, Lebanese American University, Beirut, Lebanon
- Lebanese American University Medical Center, Rizk Hospital, Beirut, Lebanon
| | - Marc Finianos
- Department of Microbiology, Faculty of Medicine, University Hospital in Pilsen, Charles University, Pilsen, Czech Republic
- Biomedical Center, Faculty of Medicine, Charles University, Pilsen, Czech Republic
| | - Ibrahim Bitar
- Department of Microbiology, Faculty of Medicine, University Hospital in Pilsen, Charles University, Pilsen, Czech Republic
- Biomedical Center, Faculty of Medicine, Charles University, Pilsen, Czech Republic
| | - Roy A Khalaf
- Department of Natural Sciences, Lebanese American University, Byblos, Lebanon
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López-Marmolejo AL, Hernández-Chávez MJ, Gutiérrez-Escobedo G, Selene Herrera-Basurto M, Mora-Montes HM, De Las Peñas A, Castaño I. Microevolution of Candida glabrata (Nakaseomyces glabrata) during an infection. Fungal Genet Biol 2024; 172:103891. [PMID: 38621582 DOI: 10.1016/j.fgb.2024.103891] [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: 09/20/2023] [Revised: 03/27/2024] [Accepted: 04/12/2024] [Indexed: 04/17/2024]
Abstract
Candida glabrata (Nakaseomyces glabrata) is an emergent and opportunistic fungal pathogen that colonizes and persists in different niches within its human host. In this work, we studied five clinical isolates from one patient (P7), that have a clonal origin, and all of which come from blood cultures except one, P7-3, obtained from a urine culture. We found phenotypic variation such as sensitivity to high temperature, oxidative stress, susceptibility to two classes of antifungal agents, and cell wall porosity. Only isolate P7-3 is highly resistant to the echinocandin caspofungin while the other four isolates from P7 are sensitive. However, this same isolate P7-3, is the only one that displays susceptibility to fluconazole (FLC), while the rest of the isolates are resistant to this antifungal. We sequenced the PDR1 gene which encodes a transcription factor required to induce the expression of several genes involved in the resistance to FLC and found that all the isolates encode for the same Pdr1 amino acid sequence except for the last isolate P7-5, which contains a single amino acid change, G1099C in the putative Pdr1 transactivation domain. Consistent with the resistance to FLC, we found that the CDR1 gene, encoding the main drug efflux pump in C. glabrata, is highly overexpressed in the FLC-resistant isolates, but not in the FLC-sensitive P7-3. In addition, the resistance to FLC observed in these isolates is dependent on the PDR1 gene. Additionally, we found that all P7 isolates have a different proportion of cell wall carbohydrates compared to our standard strains CBS138 and BG14. In P7 isolates, mannan is the most abundant cell wall component, whereas β-glucan is the most abundant component in our standard strains. Consistently, all P7 isolates have a relatively low cell wall porosity compared to our standard strains. These data show phenotypic and genotypic variability between clonal isolates from different niches within a single host, suggesting microevolution of C. glabrata during an infection.
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Affiliation(s)
- Ana L López-Marmolejo
- IPICYT, División de Biología Molecular, Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa San José No. 2055, Col. Lomas 4a Sección, San Luis Potosí CP 78216, Mexico
| | - Marco J Hernández-Chávez
- IPICYT, División de Biología Molecular, Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa San José No. 2055, Col. Lomas 4a Sección, San Luis Potosí CP 78216, Mexico
| | - Guadalupe Gutiérrez-Escobedo
- IPICYT, División de Biología Molecular, Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa San José No. 2055, Col. Lomas 4a Sección, San Luis Potosí CP 78216, Mexico
| | - M Selene Herrera-Basurto
- IPICYT, División de Biología Molecular, Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa San José No. 2055, Col. Lomas 4a Sección, San Luis Potosí CP 78216, Mexico
| | - Héctor M Mora-Montes
- Departamento de Biología, División de Ciencias Naturales, Universidad de Guanajuato, Noria Alta s/n Col. Noria Alta, Guanajuato, Gto CP36050, Mexico
| | - Alejandro De Las Peñas
- IPICYT, División de Biología Molecular, Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa San José No. 2055, Col. Lomas 4a Sección, San Luis Potosí CP 78216, Mexico
| | - Irene Castaño
- IPICYT, División de Biología Molecular, Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa San José No. 2055, Col. Lomas 4a Sección, San Luis Potosí CP 78216, Mexico
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3
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Conway TP, Simonicova L, Moye-Rowley WS. Overlapping coactivator function is required for transcriptional activation by the Candida glabrata Pdr1 transcription factor. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.24.595833. [PMID: 38853834 PMCID: PMC11160619 DOI: 10.1101/2024.05.24.595833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
Azole resistance in the pathogenic yeast Candida glabrata is a serious clinical complication and increasing in frequency. The majority of resistant organisms have been found to contain a substitution mutation in the Zn2Cys6 zinc cluster-containing transcription factor Pdr1. These mutations typically lead to this factor driving high, constitutive expression of target genes like the ATP-binding cassette transporter-encoding gene CDR1 . Overexpression of Cdr1 is required for the observed elevated fluconazole resistance exhibited by strains containing one of these hyperactive PDR1 alleles. While the identity of hyperactive PDR1 alleles has been extensively documented, the mechanisms underlying how these gain-of-function (GOF) forms of Pdr1 lead to elevated target gene transcription are not well understood. We have used a tandem affinity purification (TAP)-tagged form of Pdr1 to identify coactivator proteins that biochemically purify with the wild-type and two different GOF forms of Pdr1. Three coactivator proteins were found to associate with Pdr1: the SWI/SNF complex Snf2 chromatin remodeling protein and two different components of the SAGA complex, Spt7 and Ngg1. We found that deletion mutants lacking either SNF2 or SPT7 exhibited growth defects, even in the absence of fluconazole challenge. To overcome these issues, we employed a conditional degradation system to acutely deplete these coactivators and determined that loss of either coactivator complex, SWI/SNF or SAGA, caused defects in Pdr1-dependent transcription. A double degron strain that could be depleted for both SWI/SNF and SAGA exhibited a profound defect in PDR1 autoregulation, revealing that these complexes work together to ensure high level Pdr1-dependent gene transcription.
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Ror S, Stamnes MA, Moye-Rowley WS. Loss of a conserved C-terminal region of the Aspergillus fumigatus AtrR transcriptional regulator leads to a gene-specific defect in target gene expression. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.22.595332. [PMID: 38826412 PMCID: PMC11142210 DOI: 10.1101/2024.05.22.595332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
Treatment of fungal infections associated with the filamentous fungus Aspergillus fumigatus is becoming more problematic as this organism is developing resistance to the main chemotherapeutic drug at an increasing rate. Azole drugs represent the current standard-of-care in treatment of aspergillosis with this drug class acting by inhibiting a key step in biosynthesis of the fungal sterol ergosterol. Azole compounds block the activity of the lanosterol α-14 demethylase, encoded by the cyp51A gene. A common route of azole resistance involves an increase in transcription of cyp51A. This transcriptional increase requires the function of a Zn2Cys6 DNA-binding domain-containing transcription activator protein called AtrR. AtrR was identified through its action as a positive regulator of expression of an ATP-binding cassette transporter (abcC/cdr1B here called abcG1). Using both deletion and alanine scanning mutagenesis, we demonstrate that a conserved C-terminal domain in A. fumigatus is required for expression of abcG1 but dispensable for cyp51A transcription. This domain is also found in several other fungal pathogen AtrR homologues consistent with a conserved gene-selective function of this protein segment being conserved. Using RNA-seq, we find that this gene-specific transcriptional defect extends to several other membrane transporter-encoding genes including a second ABC transporter locus. Our data reveal that AtrR uses at least two distinct mechanisms to induce gene expression and that normal susceptibility to azole drugs cannot be provided by maintenance of wild-type expression of the ergosterol biosynthetic pathway when ABC transporter expression is reduced.
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Affiliation(s)
- Shivani Ror
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Mark A Stamnes
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - W Scott Moye-Rowley
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
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5
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Maroc L, Shaker H, Shapiro RS. Functional genetic characterization of stress tolerance and biofilm formation in Nakaseomyces ( Candida) glabrata via a novel CRISPR activation system. mSphere 2024; 9:e0076123. [PMID: 38265239 PMCID: PMC10900893 DOI: 10.1128/msphere.00761-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 12/13/2023] [Indexed: 01/25/2024] Open
Abstract
The overexpression of genes frequently arises in Nakaseomyces (formerly Candida) glabrata via gain-of-function mutations, gene duplication, or aneuploidies, with important consequences on pathogenesis traits and antifungal drug resistance. This highlights the need to develop specific genetic tools to mimic and study genetic amplification in this important fungal pathogen. Here, we report the development, validation, and applications of the first clustered regularly interspaced short palindromic repeats (CRISPR) activation (CRISPRa) system in N. glabrata for targeted genetic overexpression. Using this system, we demonstrate the ability of CRISPRa to drive high levels of gene expression in N. glabrata, and further assess optimal guide RNA targeting for robust overexpression. We demonstrate the applications of CRISPRa to overexpress genes involved in fungal pathogenesis and drug resistance and detect corresponding phenotypic alterations in these key traits, including the characterization of novel phenotypes. Finally, we capture strain variation using our CRISPRa system in two commonly used N. glabrata genetic backgrounds. Together, this tool will expand our capacity for functional genetic overexpression in this pathogen, with numerous possibilities for future applications.IMPORTANCENakaseomyces (formerly Candida) glabrata is an important fungal pathogen that is now the second leading cause of candidiasis infections. A common strategy that this pathogen employs to resist antifungal treatment is through the upregulation of gene expression, but we have limited tools available to study this phenomenon. Here, we develop, optimize, and apply the use of CRISPRa as a means to overexpress genes in N. glabrata. We demonstrate the utility of this system to overexpress key genes involved in antifungal susceptibility, stress tolerance, and biofilm growth. This tool will be an important contribution to our ability to study the biology of this important fungal pathogen.
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Affiliation(s)
- Laetitia Maroc
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Canada
| | - Hajer Shaker
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Canada
| | - Rebecca S Shapiro
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Canada
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Misas E, Seagle E, Jenkins EN, Rajeev M, Hurst S, Nunnally NS, Bentz ML, Lyman MM, Berkow E, Harrison LH, Schaffner W, Markus TM, Pierce R, Farley MM, Chow NA, Lockhart SR, Litvintseva AP. Genomic description of acquired fluconazole- and echinocandin-resistance in patients with serial Candida glabrata isolates. J Clin Microbiol 2024; 62:e0114023. [PMID: 38265207 PMCID: PMC10865870 DOI: 10.1128/jcm.01140-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 11/29/2023] [Indexed: 01/25/2024] Open
Abstract
Candida glabrata is one of the most common causes of systemic candidiasis, often resistant to antifungal medications. To describe the genomic context of emerging resistance, we conducted a retrospective analysis of 82 serially collected isolates from 33 patients from population-based candidemia surveillance in the United States. We used whole-genome sequencing to determine the genetic relationships between isolates obtained from the same patient. Phylogenetic analysis demonstrated that isolates from 29 patients were clustered by patient. The median SNPs between isolates from the same patient was 30 (range: 7-96 SNPs), while unrelated strains infected four patients. Twenty-one isolates were resistant to echinocandins, and 24 were resistant to fluconazole. All echinocandin-resistant isolates carried a mutation either in the FKS1 or FKS2 HS1 region. Of the 24 fluconazole-resistant isolates, 17 (71%) had non-synonymous polymorphisms in the PDR1 gene, which were absent in susceptible isolates. In 11 patients, a genetically related resistant isolate was collected after recovering susceptible isolates, indicating in vivo acquisition of resistance. These findings allowed us to estimate the intra-host diversity of C. glabrata and propose an upper boundary of 96 SNPs for defining genetically related isolates, which can be used to assess donor-to-host transmission, nosocomial transmission, or acquired resistance. IMPORTANCE In our study, mutations associated to azole resistance and echinocandin resistance were detected in Candida glabrata isolates using a whole-genome sequence. C. glabrata is the second most common cause of candidemia in the United States, which rapidly acquires resistance to antifungals, in vitro and in vivo.
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Affiliation(s)
- E. Misas
- Mycotic Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - E. Seagle
- Mycotic Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - E. N. Jenkins
- Mycotic Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
- ASRT, Inc., Atlanta, Georgia, USA
| | - M. Rajeev
- Mycotic Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - S. Hurst
- Mycotic Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - N. S. Nunnally
- Mycotic Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - M. L. Bentz
- Mycotic Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - M. M. Lyman
- Mycotic Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - E. Berkow
- Mycotic Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - L. H. Harrison
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - W. Schaffner
- Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - T. M. Markus
- Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - R. Pierce
- Oregon Public Health Division, Oregon Health Authority, Portland, USA
| | - M. M. Farley
- Emory University School of Medicine, Decatur, Georgia, USA
| | - N. A. Chow
- Mycotic Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - S. R. Lockhart
- Mycotic Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - A. P. Litvintseva
- Mycotic Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
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7
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Dunaiski CM, Kock MM, Chan WY, Ismail A, Peters RPH. Molecular epidemiology and antimicrobial resistance of vaginal Candida glabrata isolates in Namibia. Med Mycol 2024; 62:myae009. [PMID: 38308518 DOI: 10.1093/mmy/myae009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 12/16/2023] [Accepted: 02/01/2024] [Indexed: 02/04/2024] Open
Abstract
Candida glabrata is the most common non-albicans Candida species that causes vulvovaginal candidiasis (VVC). Given the intrinsically low susceptibility of C. glabrata to azole drugs, investigations into C. glabrata prevalence, fungal susceptibility profile, and molecular epidemiology are necessary to optimise the treatment of VVC. This molecular epidemiological study was conducted to determine antifungal drug profile, single nucleotide polymorphisms (SNPs) associated with phenotypic antifungal resistance and epidemic diversity of C. glabrata isolates from women with VVC in Namibia. Candida glabrata isolates were identified using phenotypic and molecular methods. Antifungal susceptibility of strains was determined for fluconazole, itraconazole, amphotericin B, and anidulafungin. Whole genome sequencing was used to determine SNPs in antifungal resistance genes and sequence type (ST) allocation. Among C. glabrata isolates, all (20/20; 100%) exhibited phenotypic resistance to the azole class antifungal drug, (fluconazole), and phenotypic susceptibility to the polyene class (amphotericin B), and the echinocandins (anidulafungin). Non-synonymous SNPs were identified in antifungal resistance genes of all fluconazole-resistant C. glabrata isolates including ERG6 (15%), ERG7 (15%), CgCDR1 (25%), CgPDR1 (60%), SNQ2 (10%), FKS1 (5.0%), FKS2 (5.0%), CgFPS1 (5.0%), and MSH2 (15%). ST15 (n = 8/20, 40%) was predominant. This study provides important insight into phenotypic and genotypic antifungal resistance across C. glabrata isolates from women with VVC in Namibia. In this study, azole resistance is determined by an extensive range of SNPs, while the observed polyene and echinocandin resistance-associated SNPs despite phenotypic susceptibility require further investigation.
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Affiliation(s)
- Cara M Dunaiski
- Namibia University of Sciences and Technology, Department of Health and Applied Sciences, Windhoek 10005, Namibia
- University of Pretoria, Department of Medical Microbiology, Pretoria 0001, South Africa
| | - Marleen M Kock
- University of Pretoria, Department of Medical Microbiology, Pretoria 0001, South Africa
- National Health Laboratory Service, Tshwane, Academic Division, Pretoria 3191, South Africa
| | - Wai Yin Chan
- Sequencing Core Facility, National Institute for Communicable Diseases a Division of the National Health Laboratory Service, Johannesburg 2131, South Africa
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria 0081, South Africa
- Right to care, Centurion 0157, South Africa
| | - Arshad Ismail
- Sequencing Core Facility, National Institute for Communicable Diseases a Division of the National Health Laboratory Service, Johannesburg 2131, South Africa
- Department of Biochemistry and Microbiology, Faculty of Science, Engineering and Agriculture, University of Venda, Thohoyandou 0950, South Africa
- Institute for Water and Wastewater Technology, Durban University of Technology, Durban 4000, South Africa
| | - Remco P H Peters
- University of Pretoria, Department of Medical Microbiology, Pretoria 0001, South Africa
- University of Cape Town, Division of Medical Microbiology, Cape Town 7701, South Africa
- Foundation for Professional Development, Research Unit, East London 5217, South Africa
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Wang Y, Xu J, Ben Abid F, Salah H, Sundararaju S, Al Ismail K, Wang K, Sara Matthew L, Taj-Aldeen S, Ibrahim EB, Tang P, Perez-Lopez A, Tsui CKM. Population genomic analyses reveal high diversity, recombination and nosocomial transmission among Candida glabrata ( Nakaseomyces glabrata) isolates causing invasive infections. Microb Genom 2024; 10:001179. [PMID: 38226964 PMCID: PMC10868614 DOI: 10.1099/mgen.0.001179] [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: 10/10/2023] [Accepted: 12/21/2023] [Indexed: 01/17/2024] Open
Abstract
Candida glabrata is a commensal yeast of the gastrointestinal tract and skin of humans. However, it causes opportunistic infections in immunocompromised patients, and is the second most common Candida pathogen causing bloodstream infections. Although there are many studies on the epidemiology of C. glabrata infections, the fine- and large-scale geographical nature of C. glabrata remain incompletely understood. Here we investigated both the fine- and large-scale population structure of C. glabrata through genome sequencing of 80 clinical isolates obtained from six tertiary hospitals in Qatar and by comparing with global collections. Our fine-scale analyses revealed high genetic diversity within the Qatari population of C. glabrata and identified signatures of recombination, inbreeding and clonal expansion within and between hospitals, including evidence for nosocomial transmission among coronavirus disease 2019 (COVID-19) patients. In addition to signatures of recombination at the population level, both MATa and MATα alleles were detected in most hospitals, indicating the potential for sexual reproduction in clinical environments. Comparisons with global samples showed that the Qatari C. glabrata population was very similar to those from other parts of the world, consistent with the significant role of recent anthropogenic activities in shaping its population structure. Genome-wide association studies identified both known and novel genomic variants associated with reduced susceptibilities to fluconazole, 5-flucytosine and echinocandins. Together, our genomic analyses revealed the diversity, transmission patterns and antifungal drug resistance mechanisms of C. glabrata in Qatar as well as the relationships between Qatari isolates and those from other parts of the world.
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Affiliation(s)
- Yue Wang
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
| | - Jianping Xu
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
| | - Fatma Ben Abid
- Department of Medicine, Division of Infectious Diseases, Hamad Medical Corporation, Doha, Qatar
- Weill Cornell Medicine-Qatar, Doha, Qatar
- Communicable Disease Centre, Hamad Medical Corporation, Doha, Qatar
| | - Husam Salah
- Division of Microbiology, Department of Laboratory Medicine and Pathology, Hamad Medical Corporation, Doha, Qatar
| | | | - Khalil Al Ismail
- Communicable Disease Centre, Hamad Medical Corporation, Doha, Qatar
| | - Kun Wang
- Research Department, Sidra Medicine, Doha, Qatar
| | | | - Saad Taj-Aldeen
- Division of Microbiology, Department of Laboratory Medicine and Pathology, Hamad Medical Corporation, Doha, Qatar
| | - Emad B. Ibrahim
- Division of Microbiology, Department of Laboratory Medicine and Pathology, Hamad Medical Corporation, Doha, Qatar
| | - Patrick Tang
- Weill Cornell Medicine-Qatar, Doha, Qatar
- Division of Microbiology, Department of Laboratory Medicine and Pathology, Hamad Medical Corporation, Doha, Qatar
| | - Andres Perez-Lopez
- Weill Cornell Medicine-Qatar, Doha, Qatar
- Division of Microbiology, Department of Laboratory Medicine and Pathology, Hamad Medical Corporation, Doha, Qatar
| | - Clement K. M. Tsui
- Division of Microbiology, Department of Pathology, Sidra Medicine, Doha, Qatar
- Infectious Diseases Research Laboratory, National Center for Infectious Diseases, Tan Tock Seng Hospital, Singapore, Singapore
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
- Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
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9
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Schikora-Tamarit MÀ, Gabaldón T. Recent gene selection and drug resistance underscore clinical adaptation across Candida species. Nat Microbiol 2024; 9:284-307. [PMID: 38177305 PMCID: PMC10769879 DOI: 10.1038/s41564-023-01547-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 11/06/2023] [Indexed: 01/06/2024]
Abstract
Understanding how microbial pathogens adapt to treatments, humans and clinical environments is key to infer mechanisms of virulence, transmission and drug resistance. This may help improve therapies and diagnostics for infections with a poor prognosis, such as those caused by fungal pathogens, including Candida. Here we analysed genomic variants across approximately 2,000 isolates from six Candida species (C. glabrata, C. auris, C. albicans, C. tropicalis, C. parapsilosis and C. orthopsilosis) and identified genes under recent selection, suggesting a highly complex clinical adaptation. These involve species-specific and convergently affected adaptive mechanisms, such as adhesion. Using convergence-based genome-wide association studies we identified known drivers of drug resistance alongside potentially novel players. Finally, our analyses reveal an important role of structural variants and suggest an unexpected involvement of (para)sexual recombination in the spread of resistance. Our results provide insights on how opportunistic pathogens adapt to human-related environments and unearth candidate genes that deserve future attention.
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Affiliation(s)
- Miquel Àngel Schikora-Tamarit
- Barcelona Supercomputing Centre (BSC-CNS), Barcelona, Spain
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Toni Gabaldón
- Barcelona Supercomputing Centre (BSC-CNS), Barcelona, Spain.
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain.
- Catalan Institution for Research and Advanced Studies (ICREA), Barcelona, Spain.
- Centro Investigación Biomédica En Red de Enfermedades Infecciosas, Barcelona, Spain.
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10
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Bohner F, Papp C, Takacs T, Varga M, Szekeres A, Nosanchuk JD, Vágvölgyi C, Tóth R, Gacser A. Acquired Triazole Resistance Alters Pathogenicity-Associated Features in Candida auris in an Isolate-Dependent Manner. J Fungi (Basel) 2023; 9:1148. [PMID: 38132749 PMCID: PMC10744493 DOI: 10.3390/jof9121148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 11/13/2023] [Accepted: 11/21/2023] [Indexed: 12/23/2023] Open
Abstract
Fluconazole resistance is commonly encountered in Candida auris, and the yeast frequently displays resistance to other standard drugs, which severely limits the number of effective therapeutic agents against this emerging pathogen. In this study, we aimed to investigate the effect of acquired azole resistance on the viability, stress response, and virulence of this species. Fluconazole-, posaconazole-, and voriconazole- resistant strains were generated from two susceptible C. auris clinical isolates (0381, 0387) and compared under various conditions. Several evolved strains became pan-azole-resistant, as well as echinocandin-cross-resistant. While being pan-azole-resistant, the 0381-derived posaconazole-evolved strain colonized brain tissue more efficiently than any other strain, suggesting that fitness cost is not necessarily a consequence of resistance development in C. auris. All 0387-derived evolved strains carried a loss of function mutation (R160S) in BCY1, an inhibitor of the PKA pathway. Sequencing data also revealed that posaconazole treatment can result in ERG3 mutation in C. auris. Despite using the same mechanisms to generate the evolved strains, both genotype and phenotype analysis highlighted that the development of resistance was unique for each strain. Our data suggest that C. auris triazole resistance development is a highly complex process, initiated by several pleiotropic factors.
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Affiliation(s)
- Flora Bohner
- Department of Microbiology, University of Szeged, 6726 Szeged, Hungary; (F.B.); (C.P.); (T.T.); (M.V.); (A.S.); (C.V.)
| | - Csaba Papp
- Department of Microbiology, University of Szeged, 6726 Szeged, Hungary; (F.B.); (C.P.); (T.T.); (M.V.); (A.S.); (C.V.)
| | - Tamas Takacs
- Department of Microbiology, University of Szeged, 6726 Szeged, Hungary; (F.B.); (C.P.); (T.T.); (M.V.); (A.S.); (C.V.)
| | - Mónika Varga
- Department of Microbiology, University of Szeged, 6726 Szeged, Hungary; (F.B.); (C.P.); (T.T.); (M.V.); (A.S.); (C.V.)
| | - András Szekeres
- Department of Microbiology, University of Szeged, 6726 Szeged, Hungary; (F.B.); (C.P.); (T.T.); (M.V.); (A.S.); (C.V.)
| | - Joshua D. Nosanchuk
- Department of Medicine (Infectious Diseases), Albert Einstein College of Medicine, Bronx, New York, NY 10461, USA;
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, NY 10461, USA
| | - Csaba Vágvölgyi
- Department of Microbiology, University of Szeged, 6726 Szeged, Hungary; (F.B.); (C.P.); (T.T.); (M.V.); (A.S.); (C.V.)
| | - Renáta Tóth
- Department of Microbiology, University of Szeged, 6726 Szeged, Hungary; (F.B.); (C.P.); (T.T.); (M.V.); (A.S.); (C.V.)
| | - Attila Gacser
- Department of Microbiology, University of Szeged, 6726 Szeged, Hungary; (F.B.); (C.P.); (T.T.); (M.V.); (A.S.); (C.V.)
- HCEMM-USZ Fungal Pathogens Research Group, Department of Microbiology, University of Szeged, 6726 Szeged, Hungary
- HUN-REN-USZ Pathomechanisms of Fungal Infections Research Group, University of Szeged, 6726 Szeged, Hungary
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11
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Czajka KM, Venkataraman K, Brabant-Kirwan D, Santi SA, Verschoor C, Appanna VD, Singh R, Saunders DP, Tharmalingam S. Molecular Mechanisms Associated with Antifungal Resistance in Pathogenic Candida Species. Cells 2023; 12:2655. [PMID: 37998390 PMCID: PMC10670235 DOI: 10.3390/cells12222655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 11/14/2023] [Accepted: 11/17/2023] [Indexed: 11/25/2023] Open
Abstract
Candidiasis is a highly pervasive infection posing major health risks, especially for immunocompromised populations. Pathogenic Candida species have evolved intrinsic and acquired resistance to a variety of antifungal medications. The primary goal of this literature review is to summarize the molecular mechanisms associated with antifungal resistance in Candida species. Resistance can be conferred via gain-of-function mutations in target pathway genes or their transcriptional regulators. Therefore, an overview of the known gene mutations is presented for the following antifungals: azoles (fluconazole, voriconazole, posaconazole and itraconazole), echinocandins (caspofungin, anidulafungin and micafungin), polyenes (amphotericin B and nystatin) and 5-fluorocytosine (5-FC). The following mutation hot spots were identified: (1) ergosterol biosynthesis pathway mutations (ERG11 and UPC2), resulting in azole resistance; (2) overexpression of the efflux pumps, promoting azole resistance (transcription factor genes: tac1 and mrr1; transporter genes: CDR1, CDR2, MDR1, PDR16 and SNQ2); (3) cell wall biosynthesis mutations (FKS1, FKS2 and PDR1), conferring resistance to echinocandins; (4) mutations of nucleic acid synthesis/repair genes (FCY1, FCY2 and FUR1), resulting in 5-FC resistance; and (5) biofilm production, promoting general antifungal resistance. This review also provides a summary of standardized inhibitory breakpoints obtained from international guidelines for prominent Candida species. Notably, N. glabrata, P. kudriavzevii and C. auris demonstrate fluconazole resistance.
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Affiliation(s)
- Karolina M. Czajka
- Medical Sciences Division, NOSM University, 935 Ramsey Lake Rd., Sudbury, ON P3E 2C6, Canada; (K.M.C.); (K.V.); (C.V.); (R.S.); (D.P.S.)
| | - Krishnan Venkataraman
- Medical Sciences Division, NOSM University, 935 Ramsey Lake Rd., Sudbury, ON P3E 2C6, Canada; (K.M.C.); (K.V.); (C.V.); (R.S.); (D.P.S.)
- School of Natural Sciences, Laurentian University, Sudbury, ON P3E 2C6, Canada;
| | | | - Stacey A. Santi
- Health Sciences North Research Institute, Sudbury, ON P3E 2H2, Canada; (D.B.-K.); (S.A.S.)
| | - Chris Verschoor
- Medical Sciences Division, NOSM University, 935 Ramsey Lake Rd., Sudbury, ON P3E 2C6, Canada; (K.M.C.); (K.V.); (C.V.); (R.S.); (D.P.S.)
- School of Natural Sciences, Laurentian University, Sudbury, ON P3E 2C6, Canada;
- Health Sciences North Research Institute, Sudbury, ON P3E 2H2, Canada; (D.B.-K.); (S.A.S.)
| | - Vasu D. Appanna
- School of Natural Sciences, Laurentian University, Sudbury, ON P3E 2C6, Canada;
| | - Ravi Singh
- Medical Sciences Division, NOSM University, 935 Ramsey Lake Rd., Sudbury, ON P3E 2C6, Canada; (K.M.C.); (K.V.); (C.V.); (R.S.); (D.P.S.)
- Health Sciences North Research Institute, Sudbury, ON P3E 2H2, Canada; (D.B.-K.); (S.A.S.)
| | - Deborah P. Saunders
- Medical Sciences Division, NOSM University, 935 Ramsey Lake Rd., Sudbury, ON P3E 2C6, Canada; (K.M.C.); (K.V.); (C.V.); (R.S.); (D.P.S.)
- Health Sciences North Research Institute, Sudbury, ON P3E 2H2, Canada; (D.B.-K.); (S.A.S.)
| | - Sujeenthar Tharmalingam
- Medical Sciences Division, NOSM University, 935 Ramsey Lake Rd., Sudbury, ON P3E 2C6, Canada; (K.M.C.); (K.V.); (C.V.); (R.S.); (D.P.S.)
- School of Natural Sciences, Laurentian University, Sudbury, ON P3E 2C6, Canada;
- Health Sciences North Research Institute, Sudbury, ON P3E 2H2, Canada; (D.B.-K.); (S.A.S.)
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12
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Gale AN, Pavesic MW, Nickels TJ, Xu Z, Cormack BP, Cunningham KW. Redefining pleiotropic drug resistance in a pathogenic yeast: Pdr1 functions as a sensor of cellular stresses in Candida glabrata. mSphere 2023; 8:e0025423. [PMID: 37358297 PMCID: PMC10449514 DOI: 10.1128/msphere.00254-23] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Accepted: 05/09/2023] [Indexed: 06/27/2023] Open
Abstract
Candida glabrata is a prominent opportunistic fungal pathogen of humans. The increasing incidence of C. glabrata infections is attributed to both innate and acquired resistance to antifungals. Previous studies suggest the transcription factor Pdr1 and several target genes encoding ABC transporters are critical elements of pleiotropic defense against azoles and other antifungals. This study utilizes Hermes transposon insertion profiling to investigate Pdr1-independent and Pdr1-dependent mechanisms that alter susceptibility to the frontline antifungal fluconazole. Several new genes were found to alter fluconazole susceptibility independent of Pdr1 (CYB5, SSK1, SSK2, HOG1, TRP1). A bZIP transcription repressor of mitochondrial function (CIN5) positively regulated Pdr1 while hundreds of genes encoding mitochondrial proteins were confirmed as negative regulators of Pdr1. The antibiotic oligomycin activated Pdr1 and antagonized fluconazole efficacy likely by interfering with mitochondrial processes in C. glabrata. Unexpectedly, disruption of many 60S ribosomal proteins also activated Pdr1, thus mimicking the effects of the mRNA translation inhibitors. Cycloheximide failed to fully activate Pdr1 in a cycloheximide-resistant Rpl28-Q38E mutant. Similarly, fluconazole failed to fully activate Pdr1 in a strain expressing a low-affinity variant of Erg11. Fluconazole activated Pdr1 with very slow kinetics that correlated with the delayed onset of cellular stress. These findings are inconsistent with the idea that Pdr1 directly senses xenobiotics and support an alternative hypothesis where Pdr1 senses cellular stresses that arise only after engagement of xenobiotics with their targets. IMPORTANCE Candida glabrata is an opportunistic pathogenic yeast that causes discomfort and death. Its incidence has been increasing because of natural defenses to our common antifungal medications. This study explores the entire genome for impacts on resistance to fluconazole. We find several new and unexpected genes can impact susceptibility to fluconazole. Several antibiotics can also alter the efficacy of fluconazole. Most importantly, we find that Pdr1-a key determinant of fluconazole resistance-is not regulated directly through binding of fluconazole and instead is regulated indirectly by sensing the cellular stresses caused by fluconazole blockage of sterol biosynthesis. This new understanding of drug resistance mechanisms could improve the outcomes of current antifungals and accelerate the development of novel therapeutics.
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Affiliation(s)
- Andrew N. Gale
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, USA
| | - Matthew W. Pavesic
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, USA
| | - Timothy J. Nickels
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, USA
| | - Zhuwei Xu
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Brendan P. Cormack
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Kyle W. Cunningham
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, USA
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13
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Franconi I, Rizzato C, Poma N, Tavanti A, Lupetti A. Candida parapsilosis sensu stricto Antifungal Resistance Mechanisms and Associated Epidemiology. J Fungi (Basel) 2023; 9:798. [PMID: 37623569 PMCID: PMC10456088 DOI: 10.3390/jof9080798] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 07/18/2023] [Accepted: 07/25/2023] [Indexed: 08/26/2023] Open
Abstract
Fungal diseases cause millions of deaths per year worldwide. Antifungal resistance has become a matter of great concern in public health. In recent years rates of non-albicans species have risen dramatically. Candida parapsilosis is now reported to be the second most frequent species causing candidemia in several countries in Europe, Latin America, South Africa and Asia. Rates of acquired azole resistance are reaching a worrisome threshold from multiple reports as in vitro susceptibility testing is now starting also to explore tolerance and heteroresistance to antifungal compounds. With this review, the authors seek to evaluate known antifungal resistance mechanisms and their worldwide distribution in Candida species infections with a specific focus on C. parapsilosis.
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Affiliation(s)
- Iacopo Franconi
- Department of Translational Research on New Technologies in Medicine and Surgery, University of Pisa, Via San Zeno, 37, 56127 Pisa, Italy; (I.F.); (C.R.)
| | - Cosmeri Rizzato
- Department of Translational Research on New Technologies in Medicine and Surgery, University of Pisa, Via San Zeno, 37, 56127 Pisa, Italy; (I.F.); (C.R.)
| | - Noemi Poma
- Department of Biology, University of Pisa, Via San Zeno, 37, 56127 Pisa, Italy; (N.P.); (A.T.)
| | - Arianna Tavanti
- Department of Biology, University of Pisa, Via San Zeno, 37, 56127 Pisa, Italy; (N.P.); (A.T.)
| | - Antonella Lupetti
- Department of Translational Research on New Technologies in Medicine and Surgery, University of Pisa, Via San Zeno, 37, 56127 Pisa, Italy; (I.F.); (C.R.)
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14
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Chew KL, Achik R, Osman NH, Octavia S, Teo JWP. Genomic epidemiology of human candidaemia isolates in a tertiary hospital. Microb Genom 2023; 9:mgen001047. [PMID: 37440287 PMCID: PMC10438824 DOI: 10.1099/mgen.0.001047] [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: 06/21/2022] [Accepted: 05/17/2023] [Indexed: 07/14/2023] Open
Abstract
Invasive candida infections are significant infections that may occur in vulnerable patients with high rates of mortality or morbidity. Drug-resistance rates also appear to be on the rise which further complicate treatment options and outcomes. The aims of this study were to describe the prevalence, molecular epidemiology, and genetic features of Candida bloodstream isolates in a hospital setting. The resistance mechanisms towards the two most commonly administered antifungals, fluconazole and anidulafungin, were determined. Blood culture isolates between 1 January 2018 and 30 June 2021 positive for Candida spp. were included. Susceptibility testing was performed using Etest. Whole-genome-sequencing was performed using Illumina NovaSeq with bioinformatics analysis performed. A total of 203 isolates were sequenced: 56 C. glabrata, 53 C. tropicalis, 44 C. albicans, 36 C. parapsilosis complex (consisting of C. parapsilosis, C. orthopsilosis, and C. metapsilosis), six C. krusei, five C. dubliniensis, and three C. auris. A single cluster of azole-resistant C. tropicalis, and four clusters of C. parapsilosis isolates were observed, suggesting possible transmission occurring over several years. We found 11.3%, and 52.7 % of C. tropicalis and C. parapsilosis, respectively, clustered with other isolates, suggesting exogenous sources may play a significant role of transmission, particularly for C. parapsilosis. The clusters spanned over several years suggesting the possibility of environmental reservoirs contributing to the spread. Limited clonality was seen for C. albicans. Several sequence types appeared to be dominant for C. glabrata, however the SNP differences varied widely, indicating absence of sustained transmission.
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Affiliation(s)
- Ka Lip Chew
- Department of Laboratory Medicine, National University Hospital, Singapore, Singapore
| | - Rosemini Achik
- Department of Laboratory Medicine, National University Hospital, Singapore, Singapore
| | - Nurul Hudaa Osman
- Environmental Health Institute, National Environment Agency, Singapore, Singapore
| | - Sophie Octavia
- Environmental Health Institute, National Environment Agency, Singapore, Singapore
| | - Jeanette W. P. Teo
- Department of Laboratory Medicine, National University Hospital, Singapore, Singapore
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15
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Osset-Trénor P, Pascual-Ahuir A, Proft M. Fungal Drug Response and Antimicrobial Resistance. J Fungi (Basel) 2023; 9:jof9050565. [PMID: 37233275 DOI: 10.3390/jof9050565] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 04/27/2023] [Accepted: 05/12/2023] [Indexed: 05/27/2023] Open
Abstract
Antifungal resistance is a growing concern as it poses a significant threat to public health. Fungal infections are a significant cause of morbidity and mortality, especially in immunocompromised individuals. The limited number of antifungal agents and the emergence of resistance have led to a critical need to understand the mechanisms of antifungal drug resistance. This review provides an overview of the importance of antifungal resistance, the classes of antifungal agents, and their mode of action. It highlights the molecular mechanisms of antifungal drug resistance, including alterations in drug modification, activation, and availability. In addition, the review discusses the response to drugs via the regulation of multidrug efflux systems and antifungal drug-target interactions. We emphasize the importance of understanding the molecular mechanisms of antifungal drug resistance to develop effective strategies to combat the emergence of resistance and highlight the need for continued research to identify new targets for antifungal drug development and explore alternative therapeutic options to overcome resistance. Overall, an understanding of antifungal drug resistance and its mechanisms will be indispensable for the field of antifungal drug development and clinical management of fungal infections.
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Affiliation(s)
- Paloma Osset-Trénor
- Department of Biotechnology, Instituto de Biología Molecular y Celular de Plantas IBMCP, Universidad Politécnica de Valencia, 46022 Valencia, Spain
| | - Amparo Pascual-Ahuir
- Department of Biotechnology, Instituto de Biología Molecular y Celular de Plantas IBMCP, Universidad Politécnica de Valencia, 46022 Valencia, Spain
| | - Markus Proft
- Department of Molecular and Cellular Pathology and Therapy, Instituto de Biomedicina de Valencia IBV-CSIC, Consejo Superior de Investigaciones Científicas CSIC, 46010 Valencia, Spain
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16
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Gale AN, Pavesic MW, Nickels TJ, Xu Z, Cormack BP, Cunningham KW. Redefining Pleiotropic Drug Resistance in a Pathogenic Yeast: Pdr1 Functions as a Sensor of Cellular Stresses in Candida glabrata. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.07.539747. [PMID: 37214952 PMCID: PMC10197522 DOI: 10.1101/2023.05.07.539747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Candida glabrata is a prominent opportunistic fungal pathogen of humans. The increasing incidence of C. glabrata infections is attributed to both innate and acquired resistance to antifungals. Previous studies suggest the transcription factor Pdr1 and several target genes encoding ABC transporters are critical elements of pleiotropic defense against azoles and other antifungals. This study utilizes Hermes transposon insertion profiling to investigate Pdr1-independent and Pdr1-dependent mechanisms that alter susceptibility to the frontline antifungal fluconazole. Several new genes were found to alter fluconazole susceptibility independent of Pdr1 ( CYB5 , SSK1 , SSK2 , HOG1 , TRP1 ). A bZIP transcription repressor of mitochondrial function ( CIN5 ) positively regulated Pdr1 while hundreds of genes encoding mitochondrial proteins were confirmed as negative regulators of Pdr1. The antibiotic oligomycin activated Pdr1 and antagonized fluconazole efficacy likely by interfering with mitochondrial processes in C. glabrata . Unexpectedly, disruption of many 60S ribosomal proteins also activated Pdr1, thus mimicking the effects of the mRNA translation inhibitors. Cycloheximide failed to fully activate Pdr1 in a cycloheximide-resistant Rpl28-Q38E mutant. Similarly, fluconazole failed to fully activate Pdr1 in a strain expressing a low-affinity variant of Erg11. Fluconazole activated Pdr1 with very slow kinetics that correlated with the delayed onset of cellular stress. These findings are inconsistent with the idea that Pdr1 directly senses xenobiotics and support an alternative hypothesis where Pdr1 senses cellular stresses that arise only after engagement of xenobiotics with their targets. Importance Candida glabrata is an opportunistic pathogenic yeast that causes discomfort and death. Its incidence has been increasing because of natural defenses to our common antifungal medications. This study explores the entire genome for impacts on resistance to fluconazole. We find several new and unexpected genes can impact susceptibility to fluconazole. Several antibiotics can also alter the efficacy of fluconazole. Most importantly, we find that Pdr1 - a key determinant of fluconazole resistance - is not regulated directly through binding of fluconazole and instead is regulated indirectly by sensing the cellular stresses caused by fluconazole blockage of sterol biosynthesis. This new understanding of drug resistance mechanisms could improve the outcomes of current antifungals and accelerate the development of novel therapeutics.
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17
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Simonicova L, Moye-Rowley WS. Characterizing Candida glabrata Pdr1, a Hyperactive Transcription Factor Involved in Azole Resistance. Methods Mol Biol 2023; 2658:169-179. [PMID: 37024701 DOI: 10.1007/978-1-0716-3155-3_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/08/2023]
Abstract
This chapter illustrates how to prepare isogenic strains carrying gain-of-function forms of transcription factor Pdr1 in the human pathogen Candida glabrata. Simple steps are described that lead from a characterized plasmid-borne PDR1-GOF allele to its integration into the yeast genome in a markerless manner. Pdr1-GOF strains constructed by this approach are suitable for virulence studies in an animal host.
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Affiliation(s)
- Lucia Simonicova
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - W Scott Moye-Rowley
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, IA, USA.
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18
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Alastruey-Izquierdo A, Martín-Galiano AJ. The challenges of the genome-based identification of antifungal resistance in the clinical routine. Front Microbiol 2023; 14:1134755. [PMID: 37152754 PMCID: PMC10157239 DOI: 10.3389/fmicb.2023.1134755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Accepted: 04/05/2023] [Indexed: 05/09/2023] Open
Abstract
The increasing number of chronic and life-threatening infections caused by antimicrobial resistant fungal isolates is of critical concern. Low DNA sequencing cost may facilitate the identification of the genomic profile leading to resistance, the resistome, to rationally optimize the design of antifungal therapies. However, compared to bacteria, initiatives for resistome detection in eukaryotic pathogens are underdeveloped. Firstly, reported mutations in antifungal targets leading to reduced susceptibility must be extensively collected from the literature to generate comprehensive databases. This information should be complemented with specific laboratory screenings to detect the highest number possible of relevant genetic changes in primary targets and associations between resistance and other genomic markers. Strikingly, some drug resistant strains experience high-level genetic changes such as ploidy variation as much as duplications and reorganizations of specific chromosomes. Such variations involve allelic dominance, gene dosage increments and target expression regime effects that should be explicitly parameterized in antifungal resistome prediction algorithms. Clinical data indicate that predictors need to consider the precise pathogen species and drug levels of detail, instead of just genus and drug class. The concomitant needs for mutation accuracy and assembly quality assurance suggest hybrid sequencing approaches involving third-generation methods will be utilized. Moreover, fatal fast infections, like fungemia and meningitis, will further require both sequencing and analysis facilities are available in-house. Altogether, the complex nature of antifungal resistance demands extensive sequencing, data acquisition and processing, bioinformatic analysis pipelines, and standard protocols to be accomplished prior to genome-based protocols are applied in the clinical setting.
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Affiliation(s)
- Ana Alastruey-Izquierdo
- Mycology Reference Laboratory, National Centre for Microbiology, Instituto de Salud Carlos III, Madrid, Spain
- Center for Biomedical Research in Network in Infectious Diseases (CIBERINFEC-CB21/13/00105), Instituto de Salud Carlos III, Madrid, Spain
- *Correspondence: Ana Alastruey-Izquierdo,
| | - Antonio J. Martín-Galiano
- Core Scientific and Technical Units, Instituto de Salud Carlos III, Madrid, Spain
- Antonio J. Martín-Galiano,
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19
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Galocha M, Viana R, Pais P, Silva-Dias A, Cavalheiro M, Miranda IM, Van Ende M, Souza CS, Costa C, Branco J, Soares CM, Van Dijck P, Rodrigues AG, Teixeira MC. Genomic evolution towards azole resistance in Candida glabrata clinical isolates unveils the importance of CgHxt4/6/7 in azole accumulation. Commun Biol 2022; 5:1118. [PMID: 36271293 PMCID: PMC9587243 DOI: 10.1038/s42003-022-04087-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 10/11/2022] [Indexed: 11/09/2022] Open
Abstract
The increasing prevalence of candidosis caused by Candida glabrata is related to its ability to acquire azole resistance. Although azole resistance mechanisms are well known, the mechanisms for azole import into fungal cells have remained obscure. In this work, we have characterized two hexose transporters in C. glabrata and further investigate their role as potential azole importers. Three azole susceptible C. glabrata clinical isolates were evolved towards azole resistance and the acquired resistance phenotype was found to be independent of CgPDR1 or CgERG11 mutations. Through whole-genome sequencing, CgHXT4/6/7 was found to be mutated in the three evolved strains, when compared to their susceptible parents. CgHxt4/6/7 and the 96% identical CgHxt6/7 were found to confer azole susceptibility and increase azole accumulation in C. glabrata cells, strikingly rescuing the susceptibility phenotype imposed by CgPDR1 deletion, while the identified loss-of-function mutation in CgHXT4/6/7, leads to increased azole resistance. In silico docking analysis shows that azoles display a strong predicted affinity for the glucose binding site of CgHxt4/6/7. Altogether, we hypothesize that hexose transporters, such as CgHxt4/6/7 and CgHxt6/7, may constitute a family of azole importers, involved in clinical drug resistance in fungal pathogens, and constituting promising targets for improved antifungal therapy. Mutations in the hexose transporter, CgHXT4/6/7, contribute to increased antifungal (azole) resistance in the fungal pathogen, Candida glabrata, potentially by influencing azole accumulation.
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Affiliation(s)
- Mónica Galocha
- Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal.,iBB - Institute for Bioengineering and Biosciences, Biological Sciences Research Group, Instituto Superior Técnico, Lisbon, Portugal.,Associate Laboratory i4HB-Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
| | - Romeu Viana
- Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal.,iBB - Institute for Bioengineering and Biosciences, Biological Sciences Research Group, Instituto Superior Técnico, Lisbon, Portugal.,Associate Laboratory i4HB-Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
| | - Pedro Pais
- Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal.,iBB - Institute for Bioengineering and Biosciences, Biological Sciences Research Group, Instituto Superior Técnico, Lisbon, Portugal.,Associate Laboratory i4HB-Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
| | - Ana Silva-Dias
- Department of Microbiology, Faculty of Medicine, University of Porto, Porto, Portugal.,CINTESIS - Center for Health Technology and Services Research, Faculty of Medicine, University of Porto, Porto, Portugal
| | - Mafalda Cavalheiro
- Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal.,iBB - Institute for Bioengineering and Biosciences, Biological Sciences Research Group, Instituto Superior Técnico, Lisbon, Portugal.,Associate Laboratory i4HB-Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
| | - Isabel M Miranda
- Department of Microbiology, Faculty of Medicine, University of Porto, Porto, Portugal.,CINTESIS - Center for Health Technology and Services Research, Faculty of Medicine, University of Porto, Porto, Portugal.,Cardiovascular R&D Center, Faculty of Medicine, University of Porto, Porto, Portugal
| | - Mieke Van Ende
- Laboratory of Molecular Cell Biology, Department of Biology, Institute of Botany and Microbiology, KU Leuven, Leuven, Belgium.,VIB-KU Leuven Center for Microbiology, Leuven, Belgium
| | - Caio S Souza
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Catarina Costa
- Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal.,iBB - Institute for Bioengineering and Biosciences, Biological Sciences Research Group, Instituto Superior Técnico, Lisbon, Portugal.,Associate Laboratory i4HB-Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
| | - Joana Branco
- Department of Microbiology, Faculty of Medicine, University of Porto, Porto, Portugal.,CINTESIS - Center for Health Technology and Services Research, Faculty of Medicine, University of Porto, Porto, Portugal
| | - Cláudio M Soares
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Patrick Van Dijck
- Laboratory of Molecular Cell Biology, Department of Biology, Institute of Botany and Microbiology, KU Leuven, Leuven, Belgium.,VIB-KU Leuven Center for Microbiology, Leuven, Belgium
| | - Acácio G Rodrigues
- Department of Microbiology, Faculty of Medicine, University of Porto, Porto, Portugal. .,CINTESIS - Center for Health Technology and Services Research, Faculty of Medicine, University of Porto, Porto, Portugal.
| | - Miguel C Teixeira
- Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal. .,iBB - Institute for Bioengineering and Biosciences, Biological Sciences Research Group, Instituto Superior Técnico, Lisbon, Portugal. .,Associate Laboratory i4HB-Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal.
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20
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Bhakt P, Raney M, Kaur R. The SET-domain protein CgSet4 negatively regulates antifungal drug resistance via the ergosterol biosynthesis transcriptional regulator CgUpc2a. J Biol Chem 2022; 298:102485. [PMID: 36108742 PMCID: PMC9576903 DOI: 10.1016/j.jbc.2022.102485] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 08/30/2022] [Accepted: 09/02/2022] [Indexed: 11/27/2022] Open
Abstract
Invasive fungal infections, which pose a serious threat to human health, are increasingly associated with a high mortality rate and elevated health care costs, owing to rising resistance to current antifungals and emergence of multidrug-resistant fungal species. Candida glabrata is the second to fourth common cause of Candida bloodstream infections. Its high propensity to acquire resistance toward two mainstream drugs, azoles (inhibit ergosterol biosynthesis) and echinocandins (target cell wall), in clinical settings, and its inherent low azole susceptibility render antifungal therapy unsuccessful in many cases. Here, we demonstrate a pivotal role for the SET {suppressor of variegation 3 to 9 [Su(var)3-9], enhancer of zeste [E(z)], and trithorax (Trx)} domain-containing protein, CgSet4, in azole and echinocandin resistance via negative regulation of multidrug transporter-encoding and ergosterol biosynthesis (ERG) genes through the master transcriptional factors CgPdr1 and CgUpc2A, respectively. RNA-Seq analysis revealed that C. glabrata responds to caspofungin (CSP; echinocandin antifungal) stress by downregulation and upregulation of ERG and cell wall organization genes, respectively. Although CgSet4 acts as a repressor of the ergosterol biosynthesis pathway via CgUPC2A transcriptional downregulation, the CSP-induced ERG gene repression is not dependent on CgSet4, as CgSet4 showed diminished abundance on the CgUPC2A promoter in CSP-treated cells. Furthermore, we show a role for the last three enzymes of the ergosterol biosynthesis pathway, CgErg3, CgErg5, and CgErg4, in antifungal susceptibility and virulence in C. glabrata. Altogether, our results unveil the link between ergosterol biosynthesis and echinocandin resistance and have implications for combination antifungal therapy.
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Affiliation(s)
- Priyanka Bhakt
- Laboratory of Fungal Pathogenesis, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, India
| | - Mayur Raney
- Laboratory of Fungal Pathogenesis, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, India; Graduate Studies, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Rupinder Kaur
- Laboratory of Fungal Pathogenesis, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, India.
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21
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Vu BG, Moye-Rowley WS. Nonidentical function of Upc2A binding sites in the Candida glabrata CDR1 promoter. Genetics 2022; 222:iyac135. [PMID: 36063046 PMCID: PMC9526049 DOI: 10.1093/genetics/iyac135] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 08/15/2022] [Indexed: 01/04/2023] Open
Abstract
Increased expression of the Candida glabrata CDR1 gene, encoding an ATP-binding cassette membrane transporter, is routinely observed in fluconazole-resistant isolates of this pathogenic yeast. CDR1 transcription has been well-documented to be due to activity of the Zn2Cys6 zinc cluster-containing transcription factor Pdr1. Gain-of-function mutations in the gene encoding this factor are the most commonly observed cause of fluconazole hyper-resistance in clinical isolates. We have recently found that the sterol-responsive transcription factor Upc2A also acts to control CDR1 transcription, providing a direct link between ergosterol biosynthesis and expression of Pdr1 target genes. While this earlier work implicated Upc2A as an activator of CDR1 transcription, our further analyses revealed the presence of a second Upc2A binding site that negatively regulated CDR1 expression. This Upc2A binding site designated a sterol-responsive element (SRE) was found to have significant lower affinity for Upc2A DNA-binding than the previously described SRE. This new SRE was designated SRE2 while the original, positively acting site was named SRE1. A mutant version of SRE2 prevented in vitro DNA-binding by recombinant Upc2A and, when introduced into the CDR1 promoter, caused decreased fluconazole susceptibility and increased CDR1 expression. This negative effect caused by loss of SRE2 was shown to be Pdr1 independent, consistent with the presence of at least one additional activator of CDR1 transcription. The ability of Upc2A to exert either positive or negative effects on gene expression resembles behavior of mammalian nuclear receptor proteins and reveals an unexpectedly complex nature for SRE effects on gene regulation.
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Affiliation(s)
- Bao Gia Vu
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - William Scott Moye-Rowley
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
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22
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Edlind T, Katiyar S. Intrinsically High Resistance of Candida glabrata to Hydrogen Peroxide and Its Reversal in a Fluconazole-Resistant Mutant. Antimicrob Agents Chemother 2022; 66:e0072122. [PMID: 35916516 PMCID: PMC9487529 DOI: 10.1128/aac.00721-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Affiliation(s)
- Tom Edlind
- MicrobiType LLC, Wyndmoor, Pennsylvania, USA
| | - Santosh Katiyar
- Drexel University College of Medicine, Philadelphia, Pennsylvania, USA
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23
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Artemisinin Targets Transcription Factor PDR1 and Impairs Candida glabrata Mitochondrial Function. Antioxidants (Basel) 2022; 11:antiox11101855. [PMID: 36290580 PMCID: PMC9598568 DOI: 10.3390/antiox11101855] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 09/09/2022] [Accepted: 09/16/2022] [Indexed: 11/17/2022] Open
Abstract
A limited number of antifungal drugs, the side-effect of clinical drugs and the emergence of resistance create an urgent need for new antifungal treatment agents. High-throughput drug screening and in-depth drug action mechanism analyzation are needed to address this problem. In this study, we identified that artemisinin and its derivatives possessed antifungal activity through a high-throughput screening of the FDA-approved drug library. Subsequently, drug-resistant strains construction, a molecular dynamics simulation and a transcription level analysis were used to investigate artemisinin’s action mechanism in Candida glabrata. Transcription factor pleiotropic drug resistance 1 (PDR1) was an important determinant of artemisinin’s sensitivity by regulating the drug efflux pump and ergosterol biosynthesis pathway, leading to mitochondrial dysfunction. This dysfunction was shown by a depolarization of the mitochondrial membrane potential, an enhancement of the mitochondrial membrane viscosity and an upregulation of the intracellular ROS level in fungi. The discovery shed new light on the development of antifungal agents and understanding artemisinin’s action mechanism.
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24
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Merdan O, Şişman AS, Aksoy SA, Kızıl S, Tüzemen NÜ, Yılmaz E, Ener B. Investigation of the Defective Growth Pattern and Multidrug Resistance in a Clinical Isolate of Candida glabrata Using Whole-Genome Sequencing and Computational Biology Applications. Microbiol Spectr 2022; 10:e0077622. [PMID: 35867406 PMCID: PMC9430859 DOI: 10.1128/spectrum.00776-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Accepted: 06/16/2022] [Indexed: 11/20/2022] Open
Abstract
Candida glabrata is increasingly isolated from blood cultures, and multidrug-resistant isolates have important implications for therapy. This study describes a cholesterol-dependent clinical C. glabrata isolate (ML72254) that did not grow without blood (containing cholesterol) on routine mycological media and that showed azole and amphotericin B (AmB) resistance. Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) and whole-genome sequencing (WGS) were used for species identification. A modified Etest method (Mueller-Hinton agar supplemented with 5% sheep blood) was used for antifungal susceptibility testing. WGS data were processed via the Galaxy platform, and the genomic variations of ML72254 were retrieved. A computational biology workflow utilizing web-based applications (PROVEAN, AlphaFold Colab, and Missense3D) was constructed to predict possible deleterious effects of these missense variations on protein functions. The predictive ability of this workflow was tested with previously reported missense variations in ergosterol synthesis genes of C. glabrata. ML72254 was identified as C. glabrata sensu stricto with MALDI-TOF, and WGS confirmed this identification. The MICs of fluconazole, voriconazole, and amphotericin B were >256, >32, and >32 μg/mL, respectively. A novel frameshift mutation in the ERG1 gene (Pro314fs) and many missense variations were detected in the ergosterol synthesis genes. None of the missense variations in the ML72254 ergosterol synthesis genes were deleterious, and the Pro314fs mutation was identified as the causative molecular change for a cholesterol-dependent and multidrug-resistant phenotype. This study verified that web-based computational biology solutions can be powerful tools for examining the possible impacts of missense mutations in C. glabrata. IMPORTANCE In this study, a cholesterol-dependent C. glabrata clinical isolate that confers azole and AmB resistance was investigated using artificial intelligence (AI) technologies and cloud computing applications. This is the first of the known cholesterol-dependent C. glabrata isolate to be found in Turkey. Cholesterol-dependent C. glabrata isolates are rarely isolated in clinical samples; they can easily be overlooked during routine laboratory procedures. Microbiologists therefore need to be alert when discrepancies occur between microscopic examination and growth on routine media. In addition, because these isolates confer antifungal resistance, patient management requires extra care.
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Affiliation(s)
- Osman Merdan
- Department of Medical Microbiology, Faculty of Medicine, Bursa Uludağ University, Bursa, Turkey
| | - Ayşe Sena Şişman
- Department of Clinical Microbiology and Infectious Diseases, Faculty of Medicine, Bursa Uludağ University, Bursa, Turkey
| | - Seçil Ak Aksoy
- İnegöl Vocational School, Bursa Uludağ University, Bursa, Turkey
| | - Samet Kızıl
- Department of Medical Microbiology, Faculty of Medicine, Bursa Uludağ University, Bursa, Turkey
| | - Nazmiye Ülkü Tüzemen
- Department of Medical Microbiology, Faculty of Medicine, Bursa Uludağ University, Bursa, Turkey
| | - Emel Yılmaz
- Department of Clinical Microbiology and Infectious Diseases, Faculty of Medicine, Bursa Uludağ University, Bursa, Turkey
| | - Beyza Ener
- Department of Medical Microbiology, Faculty of Medicine, Bursa Uludağ University, Bursa, Turkey
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25
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Daneshnia F, Hilmioğlu Polat S, Ilkit M, Shor E, de Almeida Júnior JN, Favarello LM, Colombo AL, Arastehfar A, Perlin DS. Determinants of fluconazole resistance and the efficacy of fluconazole and milbemycin oxim combination against Candida parapsilosis clinical isolates from Brazil and Turkey. FRONTIERS IN FUNGAL BIOLOGY 2022; 3:906681. [PMID: 37746198 PMCID: PMC10512262 DOI: 10.3389/ffunb.2022.906681] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 07/11/2022] [Indexed: 09/26/2023]
Abstract
Fluconazole-resistant Candida parapsilosis (FLZR-CP) outbreaks are a growing public health concern and have been reported in numerous countries. Patients infected with FLZR-CP isolates show fluconazole therapeutic failure and have a significantly increased mortality rate. Because fluconazole is the most widely used antifungal agent in most regions with outbreaks, it is paramount to restore its antifungal activity. Milbemycin oxim (MOX), a well-known canine endectocide, is a potent efflux pump inhibitor that significantly potentiates the activity of fluconazole against FLZR C. glabrata and C. albicans. However, the FLZ-MOX combination has not been tested against FLZR-CP isolates, nor is it known whether MOX may also potentiate the activity of echinocandins, a different class of antifungal drugs. Furthermore, the extent of involvement of efflux pumps CDR1 and MDR1 and ergosterol biosynthesis enzyme ERG11 and their link with gain-of-function (GOF) mutations in their transcription regulators (TAC1, MRR1, and UPC2) are poorly characterized among FLZR-CP isolates. We analyzed 25 C. parapsilosis isolates collected from outbreaks in Turkey and Brazil by determining the expression levels of CDR1, MDR1, and ERG11, examining the presence of potential GOF mutations in their transcriptional regulators, and assessing the antifungal activity of FLZ-MOX and micafungin-MOX against FLZR and multidrug-resistant (MDR) C. parapsilosis isolates. ERG11 was found to be universally induced by fluconazole in all isolates, while expression of MDR1 was unchanged. Whereas mutations in MRR1 and UPC2 were not detected, CDR1 was overexpressed in three Brazilian FLZR-CP isolates, which also carried a novel TAC1L518F mutation. Of these three isolates, one showed increased basal expression of CDR1, while the other two overexpressed CDR1 only in the presence of fluconazole. Interestingly, MOX showed promising antifungal activity against FLZR isolates, reducing the FLZ MIC 8- to 32-fold. However, the MOX and micafungin combination did not exert activity against an MDR C. parapsilosis isolate. Collectively, our study documents that the mechanisms underpinning FLZR are region specific, where ERG11 mutations were the sole mechanism of FLZR in Turkish FLZR-CP isolates, while simultaneous overexpression of CDR1 was observed in some Brazilian counterparts. Moreover, MOX and fluconazole showed potent synergistic activity, while the MOX-micafungin combination showed no synergy.
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Affiliation(s)
- Farnaz Daneshnia
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ, United States
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, Netherlands
| | | | - Macit Ilkit
- Division of Mycology, Faculty of Medicine, Çukurova University, Adana, Turkey
| | - Erika Shor
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ, United States
- Hackensack Meridian School of Medicine, Nutley, NJ, United States
| | - João Nobrega de Almeida Júnior
- Laboratorio de Micologia Medica (LIM 53), Instituto de Medicina Tropical, Universidade de São Paulo, São Paulo, Brazil
- Laboratório Central (LIM 03), Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil
| | - Larissa M. Favarello
- Department of Medicine, Division of Infectious Diseases, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Arnaldo Lopes Colombo
- Department of Medicine, Division of Infectious Diseases, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Amir Arastehfar
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ, United States
| | - David S. Perlin
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ, United States
- Hackensack Meridian School of Medicine, Nutley, NJ, United States
- Georgetown University Lombardi Comprehensive Cancer Center, Washington, DC, United States
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26
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Salazar SB, Pinheiro MJF, Sotti-Novais D, Soares AR, Lopes MM, Ferreira T, Rodrigues V, Fernandes F, Mira NP. Disclosing azole resistance mechanisms in resistant Candida glabrata strains encoding wild-type or gain-of-function CgPDR1 alleles through comparative genomics and transcriptomics. G3 (BETHESDA, MD.) 2022; 12:jkac110. [PMID: 35532173 PMCID: PMC9258547 DOI: 10.1093/g3journal/jkac110] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 04/25/2022] [Indexed: 12/03/2022]
Abstract
The pathogenic yeast Candida glabrata is intrinsically resilient to azoles and rapidly acquires resistance to these antifungals, in vitro and in vivo. In most cases azole-resistant C. glabrata clinical strains encode hyperactive CgPdr1 variants, however, resistant strains encoding wild-type CgPDR1 alleles have also been isolated, although remaining to be disclosed the underlying resistance mechanism. In this study, we scrutinized the mechanisms underlying resistance to azoles of 8 resistant clinical C. glabrata strains, identified along the course of epidemiological surveys undertaken in Portugal. Seven of the strains were found to encode CgPdr1 gain-of-function variants (I392M, E555K, G558C, and I803T) with the substitutions I392M and I803T being herein characterized as hyper-activating mutations for the first time. While cells expressing the wild-type CgPDR1 allele required the mediator subunit Gal11A to enhance tolerance to fluconazole, this was dispensable for cells expressing the I803T variant indicating that the CgPdr1 interactome is shaped by different gain-of-function substitutions. Genomic and transcriptomic profiling of the sole azole-resistant C. glabrata isolate encoding a wild-type CgPDR1 allele (ISTB218) revealed that under fluconazole stress this strain over-expresses various genes described to provide protection against this antifungal, while also showing reduced expression of genes described to increase sensitivity to these drugs. The overall role in driving the azole-resistance phenotype of the ISTB218 C. glabrata isolate played by these changes in the transcriptome and genome of the ISTB218 isolate are discussed shedding light into mechanisms of resistance that go beyond the CgPdr1-signalling pathway and that may alone, or in combination, pave the way for the acquisition of resistance to azoles in vivo.
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Affiliation(s)
- Sara B Salazar
- iBB, Institute for Bioengineering and Biosciences, Instituto Superior Técnico—Department of Bioengineering, Universidade de Lisboa, Lisboa 1049-001, Portugal
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Lisboa 1049-001, Portugal
| | - Maria Joana F Pinheiro
- iBB, Institute for Bioengineering and Biosciences, Instituto Superior Técnico—Department of Bioengineering, Universidade de Lisboa, Lisboa 1049-001, Portugal
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Lisboa 1049-001, Portugal
| | - Danielle Sotti-Novais
- iBB, Institute for Bioengineering and Biosciences, Instituto Superior Técnico—Department of Bioengineering, Universidade de Lisboa, Lisboa 1049-001, Portugal
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Lisboa 1049-001, Portugal
| | - Ana R Soares
- Department of Medical Sciences, Institute of Biomedicine (iBiMED), University of Aveiro, Aveiro 3810, Portugal
| | - Maria M Lopes
- Departamento de Microbiologia e Imunologia, Faculdade de Farmácia da Universidade de Lisboa, Lisboa 1649-003, Portugal
| | - Teresa Ferreira
- Laboratório de Microbiologia, Hospital Dona Estefânia (Centro Hospitalar Universitário Lisboa Central), Lisboa 1169-045, Portugal
| | - Vitória Rodrigues
- Seção de Microbiologia, Laboratório SYNLAB—Lisboa, Grupo SYNLAB Portugal, Lisboa 1070-061, Portugal
| | - Fábio Fernandes
- iBB, Institute for Bioengineering and Biosciences, Instituto Superior Técnico—Department of Bioengineering, Universidade de Lisboa, Lisboa 1049-001, Portugal
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Lisboa 1049-001, Portugal
| | - Nuno P Mira
- iBB, Institute for Bioengineering and Biosciences, Instituto Superior Técnico—Department of Bioengineering, Universidade de Lisboa, Lisboa 1049-001, Portugal
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Lisboa 1049-001, Portugal
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27
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Schrevens S, Durandau E, Tran VDT, Sanglard D. Using in vivo transcriptomics and RNA enrichment to identify genes involved in virulence of Candida glabrata. Virulence 2022; 13:1285-1303. [PMID: 35795910 PMCID: PMC9348041 DOI: 10.1080/21505594.2022.2095716] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Candida species are the most commonly isolated opportunistic fungal pathogens in humans. Candida albicans causes most of the diagnosed infections, closely followed by Candida glabrata. C. albicans is well studied, and many genes have been shown to be important for infection and colonization of the host. It is however less clear how C. glabrata infects the host. With the help of fungal RNA enrichment, we here investigated for the first time the transcriptomic profile of C. glabrata during urinary tract infection (UTI) in mice. In the UTI model, bladders and kidneys are major target organs and therefore fungal transcriptomes were addressed in these organs. Our results showed that, next to adhesins and proteases, nitrogen metabolism and regulation play a vital role during C. glabrata UTI. Genes involved in nitrogen metabolism were upregulated and among them we show that DUR1,2 (urea amidolyase) and GAP1 (amino acid permease) were important for virulence. Furthermore, we confirmed the importance of the glyoxylate cycle in the host and identified MLS1 (malate synthase) as an important gene necessary for C. glabrata virulence. In conclusion, our study shows with the support of in vivo transcriptomics how C. glabrata adapts to host conditions.
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Affiliation(s)
- Sanne Schrevens
- Institute of Microbiology, University of Lausanne and University Hospital, CH-1011 Lausanne, Switzerland
| | - Eric Durandau
- Institute of Microbiology, University of Lausanne and University Hospital, CH-1011 Lausanne, Switzerland
| | - Van Du T Tran
- Vital-IT Group, SIB Swiss Institute of Bioinformatics, CH-1015 Lausanne, Switzerland
| | - Dominique Sanglard
- Institute of Microbiology, University of Lausanne and University Hospital, CH-1011 Lausanne, Switzerland
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28
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Shahi G, Kumar M, Khandelwal NK, Banerjee A, Sarkar P, Kumari S, Esquivel BD, Chauhan N, Chattopadhyay A, White TC, Gaur NA, Singh A, Prasad R. Inositol Phosphoryl Transferase, Ipt1, Is a Critical Determinant of Azole Resistance and Virulence Phenotypes in Candida glabrata. J Fungi (Basel) 2022; 8:jof8070651. [PMID: 35887407 PMCID: PMC9322651 DOI: 10.3390/jof8070651] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 06/17/2022] [Accepted: 06/18/2022] [Indexed: 12/10/2022] Open
Abstract
In this study, we have specifically blocked a key step of sphingolipid (SL) biosynthesis in Candida glabrata by disruption of the orthologs of ScIpt1 and ScSkn1. Based on their close homology with S. cerevisiae counterparts, the proteins are predicted to catalyze the addition of a phosphorylinositol group onto mannosyl inositolphosphoryl ceramide (MIPC) to form mannosyl diinositolphosphoryl ceramide (M(IP)2C), which accounts for the majority of complex SL structures in S. cerevisiae membranes. High throughput lipidome analysis confirmed the accumulation of MIPC structures in ΔCgipt1 and ΔCgskn1 cells, albeit to lesser extent in the latter. Noticeably, ΔCgipt1 cells showed an increased susceptibility to azoles; however, ΔCgskn1 cells showed no significant changes in the drug susceptibility profiles. Interestingly, the azole susceptible phenotype of ΔCgipt1 cells seems to be independent of the ergosterol content. ΔCgipt1 cells displayed altered lipid homeostasis, increased membrane fluidity as well as high diffusion of radiolabeled fluconazole (3H-FLC), which could together influence the azole susceptibility of C. glabrata. Furthermore, in vivo experiments also confirmed compromised virulence of the ΔCgipt1 strain. Contrarily, specific functions of CgSkn1 remain unclear.
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Affiliation(s)
- Garima Shahi
- Amity Institute of Biotechnology and Integrative Science and Health, Amity University Gurgaon, Gurgaon 122412, India; (G.S.); (M.K.); (A.B.)
| | - Mohit Kumar
- Amity Institute of Biotechnology and Integrative Science and Health, Amity University Gurgaon, Gurgaon 122412, India; (G.S.); (M.K.); (A.B.)
- Yeast Biofuel Group, International Centre for Genetic Engineering and Biotechnology, New Delhi 110067, India; (S.K.); (N.A.G.)
| | | | - Atanu Banerjee
- Amity Institute of Biotechnology and Integrative Science and Health, Amity University Gurgaon, Gurgaon 122412, India; (G.S.); (M.K.); (A.B.)
| | - Parijat Sarkar
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500007, India; (P.S.); (A.C.)
| | - Sonam Kumari
- Yeast Biofuel Group, International Centre for Genetic Engineering and Biotechnology, New Delhi 110067, India; (S.K.); (N.A.G.)
| | - Brooke D. Esquivel
- School of Biological and Chemical Sciences, University of Missouri at Kansas City, Kansas City, MO 64110, USA; (B.D.E.); (T.C.W.)
| | - Neeraj Chauhan
- Department of Microbiology, Biochemistry and Molecular Genetics, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA;
| | - Amitabha Chattopadhyay
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500007, India; (P.S.); (A.C.)
| | - Theodore C. White
- School of Biological and Chemical Sciences, University of Missouri at Kansas City, Kansas City, MO 64110, USA; (B.D.E.); (T.C.W.)
| | - Naseem A. Gaur
- Yeast Biofuel Group, International Centre for Genetic Engineering and Biotechnology, New Delhi 110067, India; (S.K.); (N.A.G.)
| | - Ashutosh Singh
- Department of Biochemistry, University of Lucknow, Lucknow 226007, India
- Correspondence: (A.S.); (R.P.)
| | - Rajendra Prasad
- Amity Institute of Biotechnology and Integrative Science and Health, Amity University Gurgaon, Gurgaon 122412, India; (G.S.); (M.K.); (A.B.)
- Correspondence: (A.S.); (R.P.)
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29
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Using genomics to understand the mechanisms of virulence and drug resistance in fungal pathogens. Biochem Soc Trans 2022; 50:1259-1268. [PMID: 35713390 PMCID: PMC9246328 DOI: 10.1042/bst20211123] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 05/27/2022] [Accepted: 06/06/2022] [Indexed: 02/06/2023]
Abstract
Fungal pathogens pose an increasingly worrying threat to human health, food security and ecosystem diversity. To tackle fungal infections and improve current diagnostic and therapeutic tools it is necessary to understand virulence and antifungal drug resistance mechanisms in diverse species. Recent advances in genomics approaches have provided a suitable framework to understand these phenotypes, which ultimately depend on genetically encoded determinants. In this work, we review how the study of genome sequences has been key to ascertain the bases of virulence and drug resistance traits. We focus on the contribution of comparative genomics, population genomics and directed evolution studies. In addition, we discuss how different types of genomic mutations (small or structural variants) contribute to intraspecific differences in virulence or drug resistance. Finally, we review current challenges in the field and anticipate future directions to solve them. In summary, this work provides a short overview of how genomics can be used to understand virulence and drug resistance in fungal pathogens.
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30
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Pellaton N, Sanglard D, Lamoth F, Coste AT. How Yeast Antifungal Resistance Gene Analysis Is Essential to Validate Antifungal Susceptibility Testing Systems. Front Cell Infect Microbiol 2022; 12:859439. [PMID: 35601096 PMCID: PMC9114767 DOI: 10.3389/fcimb.2022.859439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 03/14/2022] [Indexed: 11/13/2022] Open
Abstract
ObjectivesThe antifungal susceptibility testing (AFST) of yeast pathogen alerts clinicians about the potential emergence of resistance. In this study, we compared two commercial microdilution AFST methods: Sensititre YeastOne read visually (YO) and MICRONAUT-AM read visually (MN) or spectrophotometrically (MNV), interpreted with Clinical and Laboratory Standards Institute and European Committee on Antimicrobial Susceptibility Testing criteria, respectively.MethodsOverall, 97 strains from 19 yeast species were measured for nine antifungal drugs including a total of 873 observations. First, the minimal inhibitory concentration (MIC) was compared between YO and MNV, and between MNV and MN, either directly or by assigning them to five susceptibility categories. Those categories were based on the number of MIC dilutions around the breakpoint or epidemiological cut-off reference values (ECOFFs or ECVs). Second, YO and MNV methods were evaluated for their ability to detect the elevation of MICs due to mutation in antifungal resistance genes, thanks to pairs or triplets of isogenic strains isolated from a single patient along a treatment previously analyzed for antifungal resistance gene mutations. Reproducibility measurement was evaluated, thanks to three quality control (QC) strains.ResultsYO and MNV direct MIC comparisons obtained a global agreement of 67%. Performing susceptibility category comparisons, only 22% and 49% of the MICs could be assigned to categories using breakpoints and ECOFFs/ECVs, respectively, and 40% could not be assigned due to the lack of criteria in both consortia. The YO and MN susceptibility categories gave accuracies as low as 50%, revealing the difficulty to implement this method of comparison. In contrast, using the antifungal resistance gene sequences as a gold standard, we demonstrated that both methods (YO and MN) were equally able to detect the acquisition of resistance in the Candida strains, even if MN showed a global lower MIC elevation than YO. Finally, no major differences in reproducibility were observed between the three AFST methods.ConclusionThis study demonstrates the valuable use of both commercial microdilution AFST methods to detect antifungal resistance due to point mutations in antifungal resistance genes. We highlighted the difficulty to conduct conclusive analyses without antifungal gene sequence data as a gold standard. Indeed, MIC comparisons taking into account the consortia criteria of interpretation remain difficult even after the effort of harmonization.
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Affiliation(s)
- Nicolas Pellaton
- Institute of Microbiology, University of Lausanne and University Hospital Center, Lausanne, Switzerland
| | - Dominique Sanglard
- Institute of Microbiology, University of Lausanne and University Hospital Center, Lausanne, Switzerland
| | - Frederic Lamoth
- Institute of Microbiology, University of Lausanne and University Hospital Center, Lausanne, Switzerland
- Infectious Diseases Service, Department of Medicine, Lausanne University Hospital, Lausanne, Switzerland
| | - Alix T. Coste
- Institute of Microbiology, University of Lausanne and University Hospital Center, Lausanne, Switzerland
- *Correspondence: Alix T. Coste,
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31
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Castanheira M, Deshpande LM, Davis AP, Carvalhaes CG, Pfaller MA. Azole Resistance in Candida glabrata Clinical Isolates from Global Surveillance is Associated with Efflux Overexpression. J Glob Antimicrob Resist 2022; 29:371-377. [DOI: 10.1016/j.jgar.2022.05.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 05/05/2022] [Accepted: 05/06/2022] [Indexed: 11/28/2022] Open
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32
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Nikolov VN, Malavia D, Kubota T. SWI/SNF and the histone chaperone Rtt106 drive expression of the Pleiotropic Drug Resistance network genes. Nat Commun 2022; 13:1968. [PMID: 35413952 PMCID: PMC9005695 DOI: 10.1038/s41467-022-29591-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 03/23/2022] [Indexed: 12/13/2022] Open
Abstract
The Pleiotropic Drug Resistance (PDR) network is central to the drug response in fungi, and its overactivation is associated with drug resistance. However, gene regulation of the PDR network is not well understood. Here, we show that the histone chaperone Rtt106 and the chromatin remodeller SWI/SNF control expression of the PDR network genes and confer drug resistance. In Saccharomyces cerevisiae, Rtt106 specifically localises to PDR network gene promoters dependent on transcription factor Pdr3, but not Pdr1, and is essential for Pdr3-mediated basal expression of the PDR network genes, while SWI/SNF is essential for both basal and drug-induced expression. Also in the pathogenic fungus Candida glabrata, Rtt106 and SWI/SNF regulate drug-induced PDR gene expression. Consistently, loss of Rtt106 or SWI/SNF sensitises drug-resistant S. cerevisiae mutants and C. glabrata to antifungal drugs. Since they cooperatively drive PDR network gene expression, Rtt106 and SWI/SNF represent potential therapeutic targets to combat antifungal resistance.
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Affiliation(s)
- Vladislav N Nikolov
- Institute of Medical Sciences, School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD, UK
| | - Dhara Malavia
- Institute of Medical Sciences, School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD, UK
- MRC Centre for Medical Mycology, Geoffrey Pope Building, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
| | - Takashi Kubota
- Institute of Medical Sciences, School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD, UK.
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33
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Shantal CJN, Juan CC, Lizbeth BUS, Carlos HGJ, Estela GPB. Candida glabrata is a successful pathogen: an artist manipulating the immune response. Microbiol Res 2022; 260:127038. [DOI: 10.1016/j.micres.2022.127038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Revised: 04/02/2022] [Accepted: 04/07/2022] [Indexed: 02/07/2023]
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34
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Bohner F, Papp C, Gácser A. The effect of antifungal resistance development on the virulence of Candida species. FEMS Yeast Res 2022; 22:6552956. [PMID: 35325128 PMCID: PMC9466593 DOI: 10.1093/femsyr/foac019] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 02/24/2022] [Accepted: 03/21/2022] [Indexed: 11/12/2022] Open
Abstract
In recent years, the relevance of diseases associated with fungal pathogens increased worldwide. Members of the Candida genus are responsible for the greatest number of fungal bloodstream infections every year. Epidemiological data consistently indicate a modest shift toward non-albicans species, albeit Candidaalbicans is still the most recognizable species within the genus. As a result, the number of clinically relevant pathogens has increased, and, despite their distinct pathogenicity features, the applicable antifungal agents remained the same. For bloodstream infections, only three classes of drugs are routinely used, namely polyenes, azoles and echinocandins. Antifungal resistance toward all three antifungal drug classes frequently occurs in clinical settings. Compared with the broad range of literature on virulence and antifungal resistance of Candida species separately, only a small portion of studies examined the effect of resistance on virulence. These studies found that resistance to polyenes and echinocandins concluded in significant decrease in the virulence in different Candida species. Meanwhile, in some cases, resistance to azole type antifungals resulted in increased virulence depending on the species and isolates. These findings underline the importance of studies aiming to dissect the connections of virulence and resistance in Candida species.
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Affiliation(s)
- Flora Bohner
- HCEMM-USZ Fungal Pathogens Research Group, Department of Microbiology, Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Csaba Papp
- HCEMM-USZ Fungal Pathogens Research Group, Department of Microbiology, Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Attila Gácser
- HCEMM-USZ Fungal Pathogens Research Group, Department of Microbiology, Faculty of Science and Informatics, University of Szeged, Szeged, Hungary.,MTA-SZTE "Lendület" Mycobiome Research Group, University of Szeged, Szeged, Hungary
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35
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Unmasking of CgYor1-Dependent Azole Resistance Mediated by Target of Rapamycin (TOR) and Calcineurin Signaling in Candida glabrata. mBio 2022; 13:e0354521. [PMID: 35038899 PMCID: PMC8764518 DOI: 10.1128/mbio.03545-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
In this study, 18 predicted membrane-localized ABC transporters of Candida glabrata were deleted individually to create a minilibrary of knockouts (KO). The transporter KOs were analyzed for their susceptibility toward antimycotic drugs. Although CgYOR1 has previously been reported to be upregulated in various azole-resistant clinical isolates of C. glabrata, deletion of this gene did not change the susceptibility to any of the tested azoles. Additionally, Cgyor1Δ showed no change in susceptibility toward oligomycin, which is otherwise a well-known substrate of Yor1 in other yeasts. The role of CgYor1 in azole susceptibility only became evident when the major transporter CgCDR1 gene was deleted. However, under nitrogen-depleted conditions, Cgyor1Δ demonstrated an azole-susceptible phenotype, independent of CgCdr1. Notably, Cgyor1Δ cells also showed increased susceptibility to target of rapamycin (TOR) and calcineurin inhibitors. Moreover, increased phytoceramide levels in Cgyor1Δ and the deletions of regulators downstream of TOR and the calcineurin signaling cascade (Cgypk1Δ, Cgypk2Δ, Cgckb1Δ, and Cgckb2Δ) in the Cgyor1Δ background and their associated fluconazole (FLC) susceptibility phenotypes confirmed their involvement. Collectively, our findings show that TOR and calcineurin signaling govern CgYor1-mediated azole susceptibility in C. glabrata. IMPORTANCE The increasing incidence of Candida glabrata infections in the last 40 years is a serious concern worldwide. These infections are usually associated with intrinsic azole resistance and increasing echinocandin resistance. Efflux pumps, especially ABC transporter upregulation, are one of the prominent mechanisms of azole resistance; however, only a few of them are characterized. In this study, we analyzed the mechanisms of azole resistance due to a multidrug resistance-associated protein (MRP) subfamily ABC transporter, CgYor1. We demonstrate for the first time that CgYor1 does not transport oligomycin but is involved in azole resistance. Under normal growing conditions its function is masked by major transporter CgCdr1; however, under nitrogen-depleted conditions, it displays its azole resistance function independently. Moreover, we propose that the azole susceptibility due to removal of CgYor1 is not due to its transport function but involves modulation of TOR and calcineurin cascades.
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36
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Ottilie S, Luth MR, Hellemann E, Goldgof GM, Vigil E, Kumar P, Cheung AL, Song M, Godinez-Macias KP, Carolino K, Yang J, Lopez G, Abraham M, Tarsio M, LeBlanc E, Whitesell L, Schenken J, Gunawan F, Patel R, Smith J, Love MS, Williams RM, McNamara CW, Gerwick WH, Ideker T, Suzuki Y, Wirth DF, Lukens AK, Kane PM, Cowen LE, Durrant JD, Winzeler EA. Adaptive laboratory evolution in S. cerevisiae highlights role of transcription factors in fungal xenobiotic resistance. Commun Biol 2022; 5:128. [PMID: 35149760 PMCID: PMC8837787 DOI: 10.1038/s42003-022-03076-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 01/21/2022] [Indexed: 12/24/2022] Open
Abstract
In vitro evolution and whole genome analysis were used to comprehensively identify the genetic determinants of chemical resistance in Saccharomyces cerevisiae. Sequence analysis identified many genes contributing to the resistance phenotype as well as numerous amino acids in potential targets that may play a role in compound binding. Our work shows that compound-target pairs can be conserved across multiple species. The set of 25 most frequently mutated genes was enriched for transcription factors, and for almost 25 percent of the compounds, resistance was mediated by one of 100 independently derived, gain-of-function SNVs found in a 170 amino acid domain in the two Zn2C6 transcription factors YRR1 and YRM1 (p < 1 × 10−100). This remarkable enrichment for transcription factors as drug resistance genes highlights their important role in the evolution of antifungal xenobiotic resistance and underscores the challenge to develop antifungal treatments that maintain potency. Ottilie et al. employ an experimental evolution approach to investigate the role of transcription factors in yeast chemical resistance. Most emergent mutations in resistant strains were enriched in transcription factor coding genes, highlighting their importance in drug resistance.
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Affiliation(s)
- Sabine Ottilie
- Department of Pediatrics, University of California, San Diego, Gilman Dr, La Jolla, CA, 92093, USA
| | - Madeline R Luth
- Department of Pediatrics, University of California, San Diego, Gilman Dr, La Jolla, CA, 92093, USA
| | - Erich Hellemann
- Department of Biological Sciences, University of Pittsburgh, 4249 Fifth Avenue, Pittsburgh, PA, 15260, USA
| | - Gregory M Goldgof
- Department of Pediatrics, University of California, San Diego, Gilman Dr, La Jolla, CA, 92093, USA
| | - Eddy Vigil
- Department of Pediatrics, University of California, San Diego, Gilman Dr, La Jolla, CA, 92093, USA
| | - Prianka Kumar
- Department of Pediatrics, University of California, San Diego, Gilman Dr, La Jolla, CA, 92093, USA
| | - Andrea L Cheung
- Department of Pediatrics, University of California, San Diego, Gilman Dr, La Jolla, CA, 92093, USA
| | - Miranda Song
- Department of Pediatrics, University of California, San Diego, Gilman Dr, La Jolla, CA, 92093, USA
| | - Karla P Godinez-Macias
- Department of Pediatrics, University of California, San Diego, Gilman Dr, La Jolla, CA, 92093, USA
| | - Krypton Carolino
- Department of Pediatrics, University of California, San Diego, Gilman Dr, La Jolla, CA, 92093, USA
| | - Jennifer Yang
- Department of Pediatrics, University of California, San Diego, Gilman Dr, La Jolla, CA, 92093, USA
| | - Gisel Lopez
- Department of Pediatrics, University of California, San Diego, Gilman Dr, La Jolla, CA, 92093, USA
| | - Matthew Abraham
- Department of Pediatrics, University of California, San Diego, Gilman Dr, La Jolla, CA, 92093, USA
| | - Maureen Tarsio
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York, NY, 13210, USA
| | - Emmanuelle LeBlanc
- Department of Molecular Genetics, University of Toronto, Toronto, ON, M5G 1M1, Canada
| | - Luke Whitesell
- Department of Molecular Genetics, University of Toronto, Toronto, ON, M5G 1M1, Canada
| | - Jake Schenken
- Department of Pediatrics, University of California, San Diego, Gilman Dr, La Jolla, CA, 92093, USA
| | - Felicia Gunawan
- Department of Pediatrics, University of California, San Diego, Gilman Dr, La Jolla, CA, 92093, USA
| | - Reysha Patel
- Department of Pediatrics, University of California, San Diego, Gilman Dr, La Jolla, CA, 92093, USA
| | - Joshua Smith
- Department of Pediatrics, University of California, San Diego, Gilman Dr, La Jolla, CA, 92093, USA
| | - Melissa S Love
- Calibr, a division of The Scripps Research Institutes, La Jolla, CA, 92037, USA
| | - Roy M Williams
- Department of Pediatrics, University of California, San Diego, Gilman Dr, La Jolla, CA, 92093, USA.,Aspen Neuroscience, San Diego, CA, 92121, USA
| | - Case W McNamara
- Calibr, a division of The Scripps Research Institutes, La Jolla, CA, 92037, USA
| | - William H Gerwick
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, La Jolla, CA, 92037, USA
| | - Trey Ideker
- Department of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Yo Suzuki
- Department of Synthetic Biology and Bioenergy, J. Craig Venter Institute, La Jolla, CA, 92037, USA
| | - Dyann F Wirth
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA.,Infectious Disease and Microbiome Program, Broad Institute, Cambridge, MA, 02142, USA
| | - Amanda K Lukens
- Infectious Disease and Microbiome Program, Broad Institute, Cambridge, MA, 02142, USA
| | - Patricia M Kane
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York, NY, 13210, USA
| | - Leah E Cowen
- Department of Molecular Genetics, University of Toronto, Toronto, ON, M5G 1M1, Canada
| | - Jacob D Durrant
- Department of Biological Sciences, University of Pittsburgh, 4249 Fifth Avenue, Pittsburgh, PA, 15260, USA
| | - Elizabeth A Winzeler
- Department of Pediatrics, University of California, San Diego, Gilman Dr, La Jolla, CA, 92093, USA.
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37
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Azole-resistant alleles of
ERG11
in
Candida glabrata
trigger activation of the Pdr1 and Upc2A transcription factors. Antimicrob Agents Chemother 2022; 66:e0209821. [DOI: 10.1128/aac.02098-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Azoles, the most commonly used antifungal drugs, specifically inhibit the fungal lanosterol α-14 demethylase enzyme, which is referred to as Erg11. Inhibition of Erg11 ultimately leads to a reduction in ergosterol production, an essential fungal membrane sterol. Many
Candida
species, such as
Candida albicans
, develop mutations in this enzyme which reduces the azole binding affinity and results in increased resistance.
Candida glabrata
is also a pathogenic yeast that has low intrinsic susceptibility to azole drugs and easily develops elevated resistance. In
C. glabrata
, these azole resistant mutations typically cause hyperactivity of the Pdr1 transcription factor and rarely lie within the
ERG11
gene. Here, we generated
C. glabrata
ERG11
mutations that were analogous to azole resistance alleles from
C. albicans
ERG11
. Three different Erg11 forms (Y141H, S410F, and the corresponding double mutant (DM)) conferred azole resistance in
C. glabrata
with the DM Erg11 form causing the strongest phenotype. The DM Erg11 also induced cross-resistance to amphotericin B and caspofungin. Resistance caused by the DM allele of
ERG11
imposed a fitness cost that was not observed with hyperactive
PDR1
alleles. Crucially, the presence of the DM
ERG11
allele was sufficient to activate the Pdr1 transcription factor in the absence of azole drugs. Our data indicate that azole resistance linked to changes in
ERG11
activity can involve cellular effects beyond an alteration in this key azole target enzyme. Understanding the physiology linking ergosterol biosynthesis with Pdr1-mediated regulation of azole resistance is crucial for ensuring the continued efficacy of azole drugs against
C. glabrata
.
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Vázquez-Franco N, Gutiérrez-Escobedo G, Juárez-Reyes A, Orta-Zavalza E, Castaño I, De Las Peñas A. Candida glabrata Hst1-Rfm1-Sum1 complex evolved to control virulence-related genes. Fungal Genet Biol 2021; 159:103656. [PMID: 34974188 DOI: 10.1016/j.fgb.2021.103656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 12/25/2021] [Accepted: 12/27/2021] [Indexed: 11/15/2022]
Abstract
C. glabrata is an opportunistic fungal pathogen and the second most common cause of opportunistic fungal infections in humans, that has evolved virulence factors to become a successful pathogen: strong resistance to oxidative stress, capable to adhere and form biofilms in human epithelial cells as well as to abiotic surfaces and high resistance to xenobiotics. Hst1 (a NAD+-dependent histone deacetylase), Sum1 (putative DNA binding protein) and Rfm1 (connector protein) form a complex (HRS-C) and control the resistance to oxidative stress, to xenobiotics (the antifungal fluconazole), and adherence to epithelial cells. Hst1 is functionally conserved within the Saccharomycetaceae family, Rfm1 shows a close phylogenetic relation within the Saccharomycetaceae family while Sum1 displays a distant phylogenetic relation with members of the family and is not conserved functionally. CDR1 encodes for an ABC transporter (resistance to fluconazole) negatively controlled by HRS-C, for which its binding site is located within 223 bp upstream from the ATG of CDR1. The absence of Hst1 and Sum1 renders the cells hyper-adherent, possibly due to the overexpression of AED1, EPA1, EPA22 and EPA6, all encoding for adhesins. Finally, in a neutrophil survival assay, HST1 and SUM1, are not required for survival. We propose that Sum1 in the HRS-C diverged functionally to control a set of genes implicated in virulence: adherence, resistance to xenobiotics and oxidative stress.
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Affiliation(s)
- Norma Vázquez-Franco
- IPICYT, División de Biología Molecular, Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa San José, #2055, Col. Lomas 4ª Sección, San Luis Potosí, San Luis Potosí 78216, Mexico
| | - Guadalupe Gutiérrez-Escobedo
- IPICYT, División de Biología Molecular, Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa San José, #2055, Col. Lomas 4ª Sección, San Luis Potosí, San Luis Potosí 78216, Mexico
| | - Alejandro Juárez-Reyes
- IPICYT, División de Biología Molecular, Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa San José, #2055, Col. Lomas 4ª Sección, San Luis Potosí, San Luis Potosí 78216, Mexico
| | - Emmanuel Orta-Zavalza
- Departamento de Ciencias Químico-Biológicas, Universidad Autónoma de Ciudad Juárez, Chihuahua, Mexico
| | - Irene Castaño
- IPICYT, División de Biología Molecular, Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa San José, #2055, Col. Lomas 4ª Sección, San Luis Potosí, San Luis Potosí 78216, Mexico
| | - Alejandro De Las Peñas
- IPICYT, División de Biología Molecular, Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa San José, #2055, Col. Lomas 4ª Sección, San Luis Potosí, San Luis Potosí 78216, Mexico.
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Ribeiro GF, Denes E, Heaney H, Childers DS. What 'Omics Can Tell Us About Antifungal Adaptation. FEMS Yeast Res 2021; 21:6484793. [PMID: 34958354 PMCID: PMC8755904 DOI: 10.1093/femsyr/foab070] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 12/22/2021] [Indexed: 12/01/2022] Open
Abstract
Invasive candidiasis, the most frequent healthcare-associated invasive fungal infection, is commonly caused by Candida albicans. However, in recent years other antifungal-resistant Candida species—namely Candida glabrata and Candidaauris—have emerged as a serious matter of concern. Much of our understanding of the mechanisms regulating antifungal resistance and tolerance relies on studies utilizing C. albicans, C. glabrataand the model yeast Saccharomyces cerevisiae. ‘Omics studies have been used to describe alterations in metabolic, genomic and transcriptomic expression profiles upon antifungal treatment of fungal cells. The physiological changes identified by these approaches could significantly affect fungal fitness in the host and survival during antifungal challenge, as well as provide further understanding of clinical resistance. Thus, this review aims to comparatively address ‘omics data for C. albicans, C. glabrata andS. cerevisiae published from 2000 to 2021 to identify what these technologies can tell us regarding cellular responses to antifungal therapy. We will also highlight possible effects on pathogen survival and identify future avenues for antifungal research.
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Affiliation(s)
- Gabriela Fior Ribeiro
- University of Aberdeen, Institute of Medical Sciences, Aberdeen Fungal Group, Aberdeen, UK, AB25 2ZD
| | - Eszter Denes
- University of Aberdeen, Institute of Medical Sciences, Aberdeen Fungal Group, Aberdeen, UK, AB25 2ZD
| | - Helen Heaney
- University of Aberdeen, Institute of Medical Sciences, Aberdeen Fungal Group, Aberdeen, UK, AB25 2ZD
| | - Delma S Childers
- University of Aberdeen, Institute of Medical Sciences, Aberdeen Fungal Group, Aberdeen, UK, AB25 2ZD
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40
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Ksiezopolska E, Schikora-Tamarit MÀ, Beyer R, Nunez-Rodriguez JC, Schüller C, Gabaldón T. Narrow mutational signatures drive acquisition of multidrug resistance in the fungal pathogen Candida glabrata. Curr Biol 2021; 31:5314-5326.e10. [PMID: 34699784 PMCID: PMC8660101 DOI: 10.1016/j.cub.2021.09.084] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 07/20/2021] [Accepted: 09/29/2021] [Indexed: 01/25/2023]
Abstract
Fungal infections are a growing medical concern, in part due to increased resistance to one or multiple antifungal drugs. However, the evolutionary processes underpinning the acquisition of antifungal drug resistance are poorly understood. Here, we used experimental microevolution to study the adaptation of the yeast pathogen Candida glabrata to fluconazole and anidulafungin, two widely used antifungal drugs with different modes of action. Our results show widespread ability of rapid adaptation to one or both drugs. Resistance, including multidrug resistance, is often acquired at moderate fitness costs and mediated by mutations in a limited set of genes that are recurrently and specifically mutated in strains adapted to each of the drugs. Importantly, we uncover a dual role of ERG3 mutations in resistance to anidulafungin and cross-resistance to fluconazole in a subset of anidulafungin-adapted strains. Our results shed light on the mutational paths leading to resistance and cross-resistance to antifungal drugs.
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Affiliation(s)
- Ewa Ksiezopolska
- Barcelona Supercomputing Centre (BSC-CNS), Life Sciences Department, Jordi Girona 29, 08034 Barcelona, Spain; Institute for Research in Biomedicine (IRB Barcelona), Mechanisms of Disease Program, The Barcelona Institute of Science and Technology, Baldiri Reixac 10, 08028 Barcelona, Spain
| | - Miquel Àngel Schikora-Tamarit
- Barcelona Supercomputing Centre (BSC-CNS), Life Sciences Department, Jordi Girona 29, 08034 Barcelona, Spain; Institute for Research in Biomedicine (IRB Barcelona), Mechanisms of Disease Program, The Barcelona Institute of Science and Technology, Baldiri Reixac 10, 08028 Barcelona, Spain
| | - Reinhard Beyer
- Institute of Microbial Genetics and Core Facility Bioactive Substances: Screening and Analysis, University of Natural Resources and Life Sciences, Vienna (BOKU), Konrad Lorenz Strasse 24, 3430 Tulln an der Donau, Austria
| | - Juan Carlos Nunez-Rodriguez
- Barcelona Supercomputing Centre (BSC-CNS), Life Sciences Department, Jordi Girona 29, 08034 Barcelona, Spain; Institute for Research in Biomedicine (IRB Barcelona), Mechanisms of Disease Program, The Barcelona Institute of Science and Technology, Baldiri Reixac 10, 08028 Barcelona, Spain
| | - Christoph Schüller
- Institute of Microbial Genetics and Core Facility Bioactive Substances: Screening and Analysis, University of Natural Resources and Life Sciences, Vienna (BOKU), Konrad Lorenz Strasse 24, 3430 Tulln an der Donau, Austria
| | - Toni Gabaldón
- Barcelona Supercomputing Centre (BSC-CNS), Life Sciences Department, Jordi Girona 29, 08034 Barcelona, Spain; Institute for Research in Biomedicine (IRB Barcelona), Mechanisms of Disease Program, The Barcelona Institute of Science and Technology, Baldiri Reixac 10, 08028 Barcelona, Spain; Catalan Institution for Research and Advanced Studies (ICREA), Passeig Lluis Companys 23, 08010 Barcelona, Spain.
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Wang Q, Li Y, Cai X, Li R, Zheng B, Yang E, Liang T, Yang X, Wan Z, Liu W. Two Sequential Clinical Isolates of Candida glabrata with Multidrug-Resistance to Posaconazole and Echinocandins. Antibiotics (Basel) 2021; 10:antibiotics10101217. [PMID: 34680798 PMCID: PMC8532709 DOI: 10.3390/antibiotics10101217] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 09/28/2021] [Accepted: 10/02/2021] [Indexed: 12/17/2022] Open
Abstract
Candida glabrata is one of the most prevalent causative pathogens of invasive candidiasis, and multidrug-resistant strains are emerging. We identified two clinical isolates of C. glabrata, BMU10720 and BMU10722 sequentially isolated from one patient with multidrug-resistance to posaconazole (POS), caspofungin (CAS), micafungin (MCF), and anidulafungin (ANF). Overexpression of ERG11 in BMU10720 and CDR1 in BMU10722 were detected at basal level. When exposed to POS, CDR1 was significantly up-regulated in both isolates compared with susceptible reference strain, while ERG11 was up-regulated considerably only in BMU10720. PDR1 sequencing revealed that both isolates harbored P76S, P143T, and D243N substitutions, while ERG11 was intact. Cdr1 inhibitor FK520 reversed POS-resistance by down-regulating ERG11 expression. FKS sequencing revealed that both isolates harbored S663P substitution in FKS2, and four single nucleotide polymorphisms (SNPs) existed in FKS2 genes between BMU10720 and BMU10722, while FKS1 was intact. Both FKS1 and FKS2 were up-regulated by CAS in BMU10720 and BMU10722. FK520 down-regulated FKS2 expression induced by CAS through inhibiting calcineurin, resulting in synergic effect with echinocandins as well as Congo Red and Calcofluor White, two cell wall-perturbing agents. In conclusion, the multidrug-resistance of C. glabrata isolates in our study was conferred by different mechanisms. CDR1 and ERG11 overexpression in one isolate and only CDR1 overexpression in the other isolate may mediate POS-resistance. S663P mutation in FKS2 and up-regulation of FKS2 may contribute to echinocandin-resistance in both isolates.
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Affiliation(s)
- Qiqi Wang
- Department of Dermatology and Venerology, Peking University First Hospital, Beijing 100034, China; (Q.W.); (R.L.); (T.L.); (X.Y.); (Z.W.)
- National Clinical Research Center for Skin and Immune Diseases, Beijing 100034, China
- Research Center for Medical Mycology, Peking University, Beijing 100034, China
- Beijing Key Laboratory of Molecular Diagnosis on Dermatoses, Beijing 100034, China
| | - Yun Li
- Institute of Clinical Pharmacology, Peking University First Hospital, Beijing 100034, China; (Y.L.); (B.Z.)
| | - Xuan Cai
- Department of Clinical Laboratory, Renmin Hospital of Wuhan University, Wuhan 430060, China;
| | - Ruoyu Li
- Department of Dermatology and Venerology, Peking University First Hospital, Beijing 100034, China; (Q.W.); (R.L.); (T.L.); (X.Y.); (Z.W.)
- National Clinical Research Center for Skin and Immune Diseases, Beijing 100034, China
- Research Center for Medical Mycology, Peking University, Beijing 100034, China
- Beijing Key Laboratory of Molecular Diagnosis on Dermatoses, Beijing 100034, China
| | - Bo Zheng
- Institute of Clinical Pharmacology, Peking University First Hospital, Beijing 100034, China; (Y.L.); (B.Z.)
| | - Ence Yang
- Department of Microbiology & Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China;
| | - Tianyu Liang
- Department of Dermatology and Venerology, Peking University First Hospital, Beijing 100034, China; (Q.W.); (R.L.); (T.L.); (X.Y.); (Z.W.)
- National Clinical Research Center for Skin and Immune Diseases, Beijing 100034, China
- Research Center for Medical Mycology, Peking University, Beijing 100034, China
- Beijing Key Laboratory of Molecular Diagnosis on Dermatoses, Beijing 100034, China
| | - Xinyu Yang
- Department of Dermatology and Venerology, Peking University First Hospital, Beijing 100034, China; (Q.W.); (R.L.); (T.L.); (X.Y.); (Z.W.)
- National Clinical Research Center for Skin and Immune Diseases, Beijing 100034, China
- Research Center for Medical Mycology, Peking University, Beijing 100034, China
- Beijing Key Laboratory of Molecular Diagnosis on Dermatoses, Beijing 100034, China
| | - Zhe Wan
- Department of Dermatology and Venerology, Peking University First Hospital, Beijing 100034, China; (Q.W.); (R.L.); (T.L.); (X.Y.); (Z.W.)
- National Clinical Research Center for Skin and Immune Diseases, Beijing 100034, China
- Research Center for Medical Mycology, Peking University, Beijing 100034, China
- Beijing Key Laboratory of Molecular Diagnosis on Dermatoses, Beijing 100034, China
| | - Wei Liu
- Department of Dermatology and Venerology, Peking University First Hospital, Beijing 100034, China; (Q.W.); (R.L.); (T.L.); (X.Y.); (Z.W.)
- National Clinical Research Center for Skin and Immune Diseases, Beijing 100034, China
- Research Center for Medical Mycology, Peking University, Beijing 100034, China
- Beijing Key Laboratory of Molecular Diagnosis on Dermatoses, Beijing 100034, China
- Correspondence: ; Tel.: +86-10-8357-3075
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Garcia-Rubio R, Jimenez-Ortigosa C, DeGregorio L, Quinteros C, Shor E, Perlin DS. Multifactorial Role of Mitochondria in Echinocandin Tolerance Revealed by Transcriptome Analysis of Drug-Tolerant Cells. mBio 2021; 12:e0195921. [PMID: 34372698 PMCID: PMC8406274 DOI: 10.1128/mbio.01959-21] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Fungal infections cause significant mortality and morbidity worldwide, and the limited existing antifungal reservoir is further weakened by the emergence of strains resistant to echinocandins, a first line of antifungal therapy. Candida glabrata is an opportunistic fungal pathogen that rapidly develops mutations in the echinocandin drug target β-1,3-glucan synthase (GS), which are associated with drug resistance and clinical failure. Although echinocandins are considered fungicidal in Candida sp., a subset of C. glabrata cells survive echinocandin exposure, forming a drug-tolerant cell reservoir, from which resistant mutations are thought to emerge. Despite their importance, the physiology of rare drug-tolerant cells is poorly understood. We used fluorescence-activated cell sorting to enrich for echinocandin-tolerant cells, followed by modified single-cell RNA sequencing to examine their transcriptional landscape. This analysis identified a transcriptional signature distinct from the stereotypical yeast environmental stress response and characterized by upregulation of pathways involved in chromosome structure and DNA topology and downregulation of oxidative stress responses, of which the latter was observed despite increased levels of reactive oxygen species. Further analyses implicated mitochondria in echinocandin tolerance, wherein inhibitors of mitochondrial complexes I and IV reduced echinocandin-mediated cell killing, but mutants lacking various mitochondrial components all showed an echinocandin hypotolerant phenotype. Finally, GS enzyme complexes purified from mitochondrial mutants exhibited normal in vitro inhibition kinetics, indicating that mitochondrial defects influence cell survival downstream of the drug-target interaction. Together, these results provide new insights into the C. glabrata response to echinocandins and reveal a multifactorial role of mitochondria in echinocandin tolerance. IMPORTANCE Echinocandin drugs are a first-line therapy to treat invasive candidiasis, which is a major source of morbidity and mortality worldwide. The opportunistic fungal pathogen Candida glabrata is a prominent bloodstream fungal pathogen, and it is notable for rapidly developing echinocandin-resistant strains associated with clinical failure. Echinocandin resistance is thought to emerge within a small echinocandin-tolerant subset of C. glabrata cells that are not killed by drug exposure, but mechanisms underlying echinocandin tolerance are still unknown. Here, we describe the unique transcriptional signature of echinocandin-tolerant cells and the results of follow-up analyses, which reveal a multifactorial role of mitochondria in C. glabrata echinocandin tolerance. In particular, although chemical inhibition of respiratory chain enzymes increased echinocandin tolerance, deletion of multiple mitochondrial components made C. glabrata cells hypotolerant to echinocandins. Together, these results provide new insights into the C. glabrata response to echinocandins and reveal the involvement of mitochondria in echinocandin tolerance.
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Affiliation(s)
- Rocio Garcia-Rubio
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, New Jersey, USA
| | | | - Lucius DeGregorio
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, New Jersey, USA
| | - Christopher Quinteros
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, New Jersey, USA
| | - Erika Shor
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, New Jersey, USA
- Department of Medical Sciences, Hackensack Meridian Health School of Medicine, Nutley, New Jersey, USA
| | - David S. Perlin
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, New Jersey, USA
- Department of Medical Sciences, Hackensack Meridian Health School of Medicine, Nutley, New Jersey, USA
- Lombardi Comprehensive Cancer Center, Department of Microbiology and Immunology, Georgetown University, Washington, DC, USA
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Won EJ, Choi MJ, Kim MN, Yong D, Lee WG, Uh Y, Kim TS, Byeon SA, Lee SY, Kim SH, Shin JH. Fluconazole-Resistant Candida glabrata Bloodstream Isolates, South Korea, 2008-2018. Emerg Infect Dis 2021; 27:779-788. [PMID: 33624581 PMCID: PMC7920659 DOI: 10.3201/eid2703.203482] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
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Abstract
Pathogenic fungi have several mechanisms of resistance to antifungal drugs, driven by the genetic plasticity and versatility of their homeostatic responses to stressful environmental cues. We critically review the molecular mechanisms of resistance and cellular adaptations of pathogenic fungi in response to antifungals and discuss the factors contributing to such resistance. We offer suggestions for the translational and clinical research agenda of this rapidly evolving and medically important field. A better understanding of antifungal resistance should assist in developing better detection tools and inform optimal strategies for preventing and treating refractory mycoses in the future.
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Affiliation(s)
- Ronen Ben-Ami
- Infectious Diseases Department, Sackler School of Medicine, Tel Aviv University, Tel Aviv Sourasky Medical Center, 6 Weizmann, Tel Aviv 64239, Israel
| | - Dimitrios P Kontoyiannis
- Infectious Diseases, University of Texas M D Anderson Cancer Center, 1515 Holcombe, Houston, TX 77030, USA.
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Two Functionally Redundant FK506-Binding Proteins Regulate Multidrug Resistance Gene Expression and Govern Azole Antifungal Resistance. Antimicrob Agents Chemother 2021; 65:AAC.02415-20. [PMID: 33722894 DOI: 10.1128/aac.02415-20] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Accepted: 03/06/2021] [Indexed: 12/14/2022] Open
Abstract
Increasing resistance to antifungal therapy is an impediment to the effective treatment of fungal infections. Candida glabrata is an opportunistic human fungal pathogen that is inherently less susceptible to cost-effective azole antifungals. Gain-of-function mutations in the Zn-finger pleiotropic drug resistance transcriptional activator-encoding gene CgPDR1 are the most prevalent causes of azole resistance in clinical settings. CgPDR1 is also transcriptionally activated upon azole exposure; however, factors governing CgPDR1 gene expression are not yet fully understood. Here, we have uncovered a novel role for two FK506-binding proteins, CgFpr3 and CgFpr4, in the regulation of the CgPDR1 regulon. We show that CgFpr3 and CgFpr4 possess a peptidyl-prolyl isomerase domain and act redundantly to control CgPDR1 expression, as a Cgfpr3Δ4Δ mutant displayed elevated expression of the CgPDR1 gene along with overexpression of its target genes, CgCDR1, CgCDR2, and CgSNQ2, which code for ATP-binding cassette multidrug transporters. Furthermore, CgFpr3 and CgFpr4 are required for the maintenance of histone H3 and H4 protein levels, and fluconazole exposure leads to elevated H3 and H4 protein levels. Consistent with the role of histone proteins in azole resistance, disruption of genes coding for the histone demethylase CgRph1 and the histone H3K36-specific methyltransferase CgSet2 leads to increased and decreased susceptibility to fluconazole, respectively, with the Cgrph1Δ mutant displaying significantly lower basal expression levels of the CgPDR1 and CgCDR1 genes. These data underscore a hitherto unknown role of histone methylation in modulating the most common azole antifungal resistance mechanism. Altogether, our findings establish a link between CgFpr-mediated histone homeostasis and CgPDR1 gene expression and implicate CgFpr in the virulence of C. glabrata.
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Abbes S, Sellami H, Neji S, Trabelsi H, Makni F, Ayadi A. Implication of efflux pumps and ERG11 genes in resistance of clinical Trichosporon asahii isolates to fluconazole. J Med Microbiol 2021; 70. [PMID: 33688802 DOI: 10.1099/jmm.0.001236] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Introduction. Trichosporon asahii has been recognized as an opportunistic agent having a limited sensitivity to antifungal treatment.Hypothesis/Gap Statement. Molecular mechanisms of azole resistance have been rarely reported for Trichosproron asahii. Similar to other fungi, we hypothesized that both ERG11 gene mutation and efflux pumps genes hyper-expression were implicated.Aim. The current work aimed to study the sensitivity of clinical T. asahii isolates to different antifungal agents and to explore their resistance mechanisms by molecular methods including real-time PCR and gene sequencing.Methods. The sensitivity of T. asahii isolates to fluconazole, amphotericin B and voriconazole was estimated by the Etest method. Real-time PCR was used to measure the relative expression of Pdr11, Mdr and ERG11 genes via the ACT1 housekeeping gene. Three pairs of primers were also chosen to sequence the ERG11 gene. This exploration was followed by statistical study including the receiver operating characteristic (ROC) curve analysis to identify a relationship between gene mean expression and the sensitivity of isolates.Results. In 31 clinical isolates, the resistance frequencies were 87, 16.1 and 3.2 %, respectively, for amphotericin B, fluconazole and voriconazole. Quantitative real-time PCR demonstrated that only Mdr over-expression was significantly associated with FCZ resistance confirmed by univariate statistical study and the ROC curve analysis (P <0.05). The ERG11 sequencing revealed two mutations H380G and S381A in TN325U11 (MIC FCZ=8 µg ml-1) and H437R in TN114U09 (MIC FCZ=256 µg ml-1) in highly conserved regions (close to the haem-binding domain) but their involvement in the resistance mechanism has not yet been assigned.Conclusion. T. asahii FCZ resistance mechanisms are proven to be much more complex and gene alteration sequence and/or expression can be involved. Only Mdr gene over-expression was significantly associated with FCZ resistance and no good correlation was observed between FCZ and VCZ MIC values and relative gene expression. ERG11 sequence alteration seems to play a major role in T. asahii FCZ resistance mechanism but their involvement needs further confirmation.
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Affiliation(s)
- S Abbes
- Fungal and Parasitic Molecular Biology Laboratory, School of Medicine, University of Sfax, Sfax, Tunisia
| | - H Sellami
- Fungal and Parasitic Molecular Biology Laboratory, School of Medicine, University of Sfax, Sfax, Tunisia
| | - S Neji
- Fungal and Parasitic Molecular Biology Laboratory, School of Medicine, University of Sfax, Sfax, Tunisia
| | - H Trabelsi
- Fungal and Parasitic Molecular Biology Laboratory, School of Medicine, University of Sfax, Sfax, Tunisia
| | - F Makni
- Fungal and Parasitic Molecular Biology Laboratory, School of Medicine, University of Sfax, Sfax, Tunisia
| | - A Ayadi
- Fungal and Parasitic Molecular Biology Laboratory, School of Medicine, University of Sfax, Sfax, Tunisia
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Arastehfar A, Gabaldón T, Garcia-Rubio R, Jenks JD, Hoenigl M, Salzer HJF, Ilkit M, Lass-Flörl C, Perlin DS. Drug-Resistant Fungi: An Emerging Challenge Threatening Our Limited Antifungal Armamentarium. Antibiotics (Basel) 2020; 9:antibiotics9120877. [PMID: 33302565 PMCID: PMC7764418 DOI: 10.3390/antibiotics9120877] [Citation(s) in RCA: 91] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 11/02/2020] [Accepted: 12/03/2020] [Indexed: 12/14/2022] Open
Abstract
The high clinical mortality and economic burden posed by invasive fungal infections (IFIs), along with significant agricultural crop loss caused by various fungal species, has resulted in the widespread use of antifungal agents. Selective drug pressure, fungal attributes, and host- and drug-related factors have counteracted the efficacy of the limited systemic antifungal drugs and changed the epidemiological landscape of IFIs. Species belonging to Candida, Aspergillus, Cryptococcus, and Pneumocystis are among the fungal pathogens showing notable rates of antifungal resistance. Drug-resistant fungi from the environment are increasingly identified in clinical settings. Furthermore, we have a limited understanding of drug class-specific resistance mechanisms in emerging Candida species. The establishment of antifungal stewardship programs in both clinical and agricultural fields and the inclusion of species identification, antifungal susceptibility testing, and therapeutic drug monitoring practices in the clinic can minimize the emergence of drug-resistant fungi. New antifungal drugs featuring promising therapeutic profiles have great promise to treat drug-resistant fungi in the clinical setting. Mitigating antifungal tolerance, a prelude to the emergence of resistance, also requires the development of effective and fungal-specific adjuvants to be used in combination with systemic antifungals.
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Affiliation(s)
- Amir Arastehfar
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ 07110, USA; (A.A.); (R.G.-R.)
| | - Toni Gabaldón
- Life Sciences Programme, Supercomputing Center (BSC-CNS), Jordi Girona, 08034 Barcelona, Spain;
- Mechanisms of Disease Programme, Institute for Research in Biomedicine (IRB), 08024 Barcelona, Spain
- Catalan Institution for Research and Advanced Studies. Pg. Lluís Companys 23, 08010 Barcelona, Spain
| | - Rocio Garcia-Rubio
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ 07110, USA; (A.A.); (R.G.-R.)
| | - Jeffrey D. Jenks
- Department of Medicine, University of California San Diego, San Diego, CA 92103, USA;
- Clinical and Translational Fungal-Working Group, University of California San Diego, La Jolla, CA 92093, USA;
- Division of Infectious Diseases and Global Public Health, Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA
| | - Martin Hoenigl
- Clinical and Translational Fungal-Working Group, University of California San Diego, La Jolla, CA 92093, USA;
- Division of Infectious Diseases and Global Public Health, Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA
- Section of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Medical University of Graz, 8036 Graz, Austria
| | | | - Macit Ilkit
- Division of Mycology, University of Çukurova, 01330 Adana, Turkey
- Correspondence: (M.I.); (D.S.P.); Tel.: +90-532-286-0099 (M.I.); +1-201-880-3100 (D.S.P.)
| | - Cornelia Lass-Flörl
- Institute of Hygiene and Medical Microbiology, Medical University of Innsbruck, 6020 Innsbruck, Austria;
| | - David S. Perlin
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ 07110, USA; (A.A.); (R.G.-R.)
- Correspondence: (M.I.); (D.S.P.); Tel.: +90-532-286-0099 (M.I.); +1-201-880-3100 (D.S.P.)
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Evaluation of Two Commercial Broth Microdilution Methods Using Different Interpretive Criteria for the Detection of Molecular Mechanisms of Acquired Azole and Echinocandin Resistance in Four Common Candida Species. Antimicrob Agents Chemother 2020; 64:AAC.00740-20. [PMID: 32900684 DOI: 10.1128/aac.00740-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 08/31/2020] [Indexed: 01/05/2023] Open
Abstract
The abilities of the new Vitek 2 AST-YS08 (YS08) and Sensititre YeastOne (SYO) systems to detect the resistances of Candida isolates to azoles and echinocandins were evaluated. In total, 292 isolates, including 28 Candida albicans (6 Erg11 and 2 Fks mutants), 57 Candida parapsilosis (26 Erg11 mutants), 24 Candida tropicalis (10 Erg11 and 1 Fks mutants), and 183 Candida glabrata (39 Pdr1 and 13 Fks mutants) isolates, were tested. The categorical agreements (CAs) between the Clinical and Laboratory Standards Institute (CLSI) method and YS08 fluconazole MICs obtained using clinical breakpoints were 92.4% (C. albicans), 96.5% (C. parapsilosis), and 87.0% (C. tropicalis), and the CAs between the CLSI and SYO MICs were 92.3% (C. albicans), 77.2% (C. parapsilosis), 100% (C. tropicalis), and 98.9% (C. glabrata). For C. glabrata, the CAs with the CLSI micafungin MICs were 92.4% and 55.5% for the YS08 micafungin and caspofungin MICs, respectively; they were 100%, 95.6%, and 98.9% for the SYO micafungin, caspofungin, and anidulafungin MICs, respectively. YS08 does not provide fluconazole data for C. glabrata; the CA with the CLSI fluconazole MIC was 97.8% for the YS08 voriconazole MIC, using an epidemiological cutoff value (ECV) of 0.5 μg/ml. Increased CAs with the CLSI MIC were observed for the YS08 MIC using CLSI ECVs (for fluconazole and C. tropicalis, 100%; for micafungin and C. glabrata, 98.9%) and for the SYO MIC using method-specific ECVs (for fluconazole and C. parapsilosis, 91.2%; for caspofungin and C. glabrata, 98.9%). Therefore, the YS08 and SYO systems may have different abilities to detect mechanisms of azole and echinocandin resistance in four Candida species; the use of method-specific ECVs may improve the performance of both systems.
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Farquhar KS, Flohr H, Charlebois DA. Advancing Antimicrobial Resistance Research Through Quantitative Modeling and Synthetic Biology. Front Bioeng Biotechnol 2020; 8:583415. [PMID: 33072732 PMCID: PMC7530828 DOI: 10.3389/fbioe.2020.583415] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 09/02/2020] [Indexed: 11/13/2022] Open
Abstract
Antimicrobial resistance (AMR) is an emerging global health crisis that is undermining advances in modern medicine and, if unmitigated, threatens to kill 10 million people per year worldwide by 2050. Research over the last decade has demonstrated that the differences between genetically identical cells in the same environment can lead to drug resistance. Fluctuations in gene expression, modulated by gene regulatory networks, can lead to non-genetic heterogeneity that results in the fractional killing of microbial populations causing drug therapies to fail; this non-genetic drug resistance can enhance the probability of acquiring genetic drug resistance mutations. Mathematical models of gene networks can elucidate general principles underlying drug resistance, predict the evolution of resistance, and guide drug resistance experiments in the laboratory. Cells genetically engineered to carry synthetic gene networks regulating drug resistance genes allow for controlled, quantitative experiments on the role of non-genetic heterogeneity in the development of drug resistance. In this perspective article, we emphasize the contributions that mathematical, computational, and synthetic gene network models play in advancing our understanding of AMR to discover effective therapies against drug-resistant infections.
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Affiliation(s)
| | - Harold Flohr
- Department of Physics, University of Alberta, Edmonton, AB, Canada
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Simonicova L, Moye-Rowley WS. Functional information from clinically-derived drug resistant forms of the Candida glabrata Pdr1 transcription factor. PLoS Genet 2020; 16:e1009005. [PMID: 32841236 PMCID: PMC7473514 DOI: 10.1371/journal.pgen.1009005] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 09/04/2020] [Accepted: 07/22/2020] [Indexed: 02/02/2023] Open
Abstract
Azole drugs are the most frequently used antifungal agents. The pathogenic yeast Candida glabrata acquires resistance to azole drugs via single amino acid substitution mutations eliciting a gain-of-function (GOF) hyperactive phenotype in the Pdr1 transcription factor. These GOF mutants constitutively drive high transcription of target genes such as the ATP-binding cassette transporter-encoding CDR1 locus. Previous characterization of Pdr1 has demonstrated that this factor is negatively controlled by the action of a central regulatory domain (CRD) of ~700 amino acids, in which GOF mutations are often found. Our earlier experiments demonstrated that a Pdr1 derivative in which the CRD was deleted gave rise to a transcriptional regulator that could not be maintained as the sole copy of PDR1 in the cell owing to its toxically high activity. Using a set of GOF PDR1 alleles from azole-resistant clinical isolates, we have analyzed the mechanisms acting to repress Pdr1 transcriptional activity. Our data support the view that Pdr1-dependent transactivation is mediated by a complex network of transcriptional coactivators interacting with the extreme C-terminal part of Pdr1. These coactivators include but are not limited to the Mediator component Med15A. Activity of this C-terminal domain is controlled by the CRD and requires multiple regions across the C-terminus for normal function. We also provide genetic evidence for an element within the transactivation domain that mediates the interaction of Pdr1 with coactivators on one hand while restricting Pdr1 activity on the other hand. These data indicate that GOF mutations in PDR1 block nonidentical negative inputs that would otherwise restrain Pdr1 transcriptional activation. The strong C-terminal transactivation domain of Pdr1 uses multiple different protein regions to recruit coactivators. Resistance to antibiotics is a major threat to the continued use of these lifesaving chemotherapeutic drugs. This problem is especially acute in the case of antifungal drugs as only 3 classes of these compounds exist. The pathogenic yeast Candida glabrata acquires resistance to the azole class of antifungal drugs by developing hyperactive alleles of the PDR1 gene, encoding a major inducer of azole resistance. We provide evidence that these hyperactive mutant proteins identify different negative inputs that would otherwise repress the transcriptional activity of Pdr1. Mutational analysis of the extreme C-terminus of Pdr1 indicated that this region exhibited multiple different interactions with coactivator proteins required for normal transcriptional activation of target gene expression. The data reported here shed light on the complicated nature of regulation of Pdr1 activity and identify domains in this protein that are bifunctional in their role to ensure normal factor activity. A detailed understanding of the molecular control of Pdr1 will allow strategies to be devised to reverse the azole resistance triggered by mutant forms of this protein.
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Affiliation(s)
- Lucia Simonicova
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, IA, United States of America
| | - W. Scott Moye-Rowley
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, IA, United States of America
- * E-mail:
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