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Kumawat M, Nabi B, Daswani M, Viquar I, Pal N, Sharma P, Tiwari S, Sarma DK, Shubham S, Kumar M. Role of bacterial efflux pump proteins in antibiotic resistance across microbial species. Microb Pathog 2023:106182. [PMID: 37263448 DOI: 10.1016/j.micpath.2023.106182] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 05/24/2023] [Accepted: 05/30/2023] [Indexed: 06/03/2023]
Abstract
Efflux proteins are transporter molecules that actively pump out a variety of substrates, including antibiotics, from cells to the environment. They are found in both Gram-positive and Gram-negative bacteria and eukaryotic cells. Based on their protein sequence homology, energy source, and overall structure, efflux proteins can be divided into seven groups. Multidrug efflux pumps are transmembrane proteins produced by microbes to enhance their survival in harsh environments and contribute to antibiotic resistance. These pumps are present in all bacterial genomes studied, indicating their ancestral origins. Many bacterial genes encoding efflux pumps are involved in transport, a significant contributor to antibiotic resistance in microbes. Efflux pumps are widely implicated in the extrusion of clinically relevant antibiotics from cells to the extracellular environment and, as such, represent a significant challenge to antimicrobial therapy. This review aims to provide an overview of the structures and mechanisms of action, substrate profiles, regulation, and possible inhibition of clinically relevant efflux pumps. Additionally, recent advances in research and the pharmacological exploitation of efflux pump inhibitors as a promising intervention for combating drug resistance will be discussed.
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Affiliation(s)
- Manoj Kumawat
- Department of Microbiology, ICMR- National Institute for Research in Environmental Health, Bhopal, 462030, India
| | - Bilkees Nabi
- Department of Biochemistry & Biochemical Engineering, SHUATS, Allahabad, 211007, India
| | - Muskan Daswani
- Department of Biotechnology, SantHirdaram Girls College, Bhopal, 462030, India
| | - Iqra Viquar
- Department of Biotechnology, SantHirdaram Girls College, Bhopal, 462030, India
| | - Namrata Pal
- Department of Microbiology, ICMR- National Institute for Research in Environmental Health, Bhopal, 462030, India
| | - Poonam Sharma
- Department of Microbiology, ICMR- National Institute for Research in Environmental Health, Bhopal, 462030, India
| | - Shikha Tiwari
- Department of Microbiology, ICMR- National Institute for Research in Environmental Health, Bhopal, 462030, India
| | - Devojit Kumar Sarma
- Department of Microbiology, ICMR- National Institute for Research in Environmental Health, Bhopal, 462030, India
| | - Swasti Shubham
- Department of Microbiology, ICMR- National Institute for Research in Environmental Health, Bhopal, 462030, India
| | - Manoj Kumar
- Department of Microbiology, ICMR- National Institute for Research in Environmental Health, Bhopal, 462030, India.
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Biermann AR, Hogan DA. Transcriptional Response of Candida auris to the Mrr1 Inducers Methylglyoxal and Benomyl. mSphere 2022; 7:e0012422. [PMID: 35473297 PMCID: PMC9241502 DOI: 10.1128/msphere.00124-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 03/18/2022] [Indexed: 11/20/2022] Open
Abstract
Candida auris is an urgent threat to human health due to its rapid spread in health care settings and its repeated development of multidrug resistance. Diseases that increase risk for C. auris infection, such as diabetes, kidney failure, or immunocompromising conditions, are associated with elevated levels of methylglyoxal (MG), a reactive dicarbonyl compound derived from several metabolic processes. In other Candida species, expression of MG reductase enzymes that catabolize and detoxify MG are controlled by Mrr1, a multidrug resistance-associated transcription factor, and MG induces Mrr1 activity. Here, we used transcriptomics and genetic assays to determine that C. auris MRR1a contributes to MG resistance, and that the main Mrr1a targets are an MG reductase and MDR1, which encodes a drug efflux protein. The C. auris Mrr1a regulon is smaller than Mrr1 regulons described in other species. In addition to MG, benomyl (BEN), a known Mrr1 stimulus, induces C. auris Mrr1 activity, and characterization of the MRR1a-dependent and -independent transcriptional responses revealed substantial overlap in genes that were differentially expressed in response to each compound. Additionally, we found that an MRR1 allele specific to one C. auris phylogenetic clade, clade III, encodes a hyperactive Mrr1 variant, and this activity correlated with higher MG resistance. C. auris MRR1a alleles were functional in Candida lusitaniae and were inducible by BEN, but not by MG, suggesting that the two Mrr1 inducers act via different mechanisms. Together, the data presented in this work contribute to the understanding of Mrr1 activity and MG resistance in C. auris. IMPORTANCE Candida auris is a fungal pathogen that has spread since its identification in 2009 and is of concern due to its high incidence of resistance against multiple classes of antifungal drugs. In other Candida species, the transcription factor Mrr1 plays a major role in resistance against azole antifungals and other toxins. More recently, Mrr1 has been recognized to contribute to resistance to methylglyoxal (MG), a toxic metabolic product that is often elevated in different disease states. MG can activate Mrr1 and its induction of Mdr1 which can protect against diverse challenges. The significance of this work lies in showing that MG is also an inducer of Mrr1 in C. auris, and that one of the major pathogenic C. auris lineages has an activating Mrr1 mutation that confers protection against MG.
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Affiliation(s)
- Amy R. Biermann
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Deborah A. Hogan
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
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Uthayakumar D, Sharma J, Wensing L, Shapiro RS. CRISPR-Based Genetic Manipulation of Candida Species: Historical Perspectives and Current Approaches. Front Genome Ed 2021; 2:606281. [PMID: 34713231 PMCID: PMC8525362 DOI: 10.3389/fgeed.2020.606281] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 12/09/2020] [Indexed: 12/26/2022] Open
Abstract
The Candida genus encompasses a diverse group of ascomycete fungi that have captured the attention of the scientific community, due to both their role in pathogenesis and emerging applications in biotechnology; the development of gene editing tools such as CRISPR, to analyze fungal genetics and perform functional genomic studies in these organisms, is essential to fully understand and exploit this genus, to further advance antifungal drug discovery and industrial value. However, genetic manipulation of Candida species has been met with several distinctive barriers to progress, such as unconventional codon usage in some species, as well as the absence of a complete sexual cycle in its diploid members. Despite these challenges, the last few decades have witnessed an expansion of the Candida genetic toolbox, allowing for diverse genome editing applications that range from introducing a single point mutation to generating large-scale mutant libraries for functional genomic studies. Clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 technology is among the most recent of these advancements, bringing unparalleled versatility and precision to genetic manipulation of Candida species. Since its initial applications in Candida albicans, CRISPR-Cas9 platforms are rapidly evolving to permit efficient gene editing in other members of the genus. The technology has proven useful in elucidating the pathogenesis and host-pathogen interactions of medically relevant Candida species, and has led to novel insights on antifungal drug susceptibility and resistance, as well as innovative treatment strategies. CRISPR-Cas9 tools have also been exploited to uncover potential applications of Candida species in industrial contexts. This review is intended to provide a historical overview of genetic approaches used to study the Candida genus and to discuss the state of the art of CRISPR-based genetic manipulation of Candida species, highlighting its contributions to deciphering the biology of this genus, as well as providing perspectives for the future of Candida genetics.
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Affiliation(s)
- Deeva Uthayakumar
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
| | - Jehoshua Sharma
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
| | - Lauren Wensing
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
| | - Rebecca S Shapiro
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
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Lu H, Shrivastava M, Whiteway M, Jiang Y. Candida albicans targets that potentially synergize with fluconazole. Crit Rev Microbiol 2021; 47:323-337. [PMID: 33587857 DOI: 10.1080/1040841x.2021.1884641] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Fluconazole has characteristics that make it widely used in the clinical treatment of C. albicans infections. However, fluconazole has only a fungistatic activity in C. albicans, therefore, in the long-term treatment of C. albicans infection with fluconazole, C. albicans has the potential to acquire fluconazole resistance. A promising approach to increase fluconazole's efficacy is identifying potential targets of drugs that can enhance the antifungal effect of fluconazole, or even make the drug fungicidal. In this review, we systematically provide a global overview of potential targets of drugs synergistic with fluconazole in C. albicans, identify new avenues for research on fluconazole potentiation, and highlight the promise of combinatorial strategies with fluconazole in combatting C. albicans infections.
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Affiliation(s)
- Hui Lu
- Department of Pharmacology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China
| | | | - Malcolm Whiteway
- Department of Biology, Concordia University, Montreal, QC, Canada
| | - Yuanying Jiang
- Department of Pharmacology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China
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Aguilar-Marcelino L, Al-Ani LKT, Freitas Soares FED, Moreira ALE, Téllez-Téllez M, Castañeda-Ramírez GS, Lourdes Acosta-Urdapilleta MD, Díaz-Godínez G, Pineda-Alegría JA. Formation, Resistance, and Pathogenicity of Fungal Biofilms: Current Trends and Future Challenges. Fungal Biol 2021. [DOI: 10.1007/978-3-030-60659-6_18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Biermann AR, Demers EG, Hogan DA. Mrr1 regulation of methylglyoxal catabolism and methylglyoxal-induced fluconazole resistance in Candida lusitaniae. Mol Microbiol 2020; 115:116-130. [PMID: 33319423 DOI: 10.1111/mmi.14604] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 08/26/2020] [Accepted: 09/05/2020] [Indexed: 12/11/2022]
Abstract
Transcription factor Mrr1, best known for its regulation of Candida azole resistance genes such as MDR1, regulates other genes that are poorly characterized. Among the other Mrr1-regulated genes are putative methylglyoxal reductases. Methylglyoxal (MG) is a toxic metabolite that is elevated in diabetes, uremia, and sepsis, which are diseases that increase the risk for candidiasis, and MG serves as a regulatory signal in diverse organisms. Our studies in Clavispora lusitaniae, also known as Candida lusitaniae, showed that Mrr1 regulates expression of two paralogous MG reductases, MGD1 and MGD2, and that both participate in MG resistance and MG catabolism. Exogenous MG increased Mrr1-dependent expression of MGD1 and MGD2 as well as expression of MDR1, which encodes an efflux pump that exports fluconazole. MG improved growth in the presence of fluconazole and this was largely Mrr1-dependent with contributions from a secondary transcription factor, Cap1. Increased fluconazole resistance was also observed in mutants lacking Glo1, a Mrr1-independent MG catabolic enzyme. Isolates from other Candida species displayed heterogeneity in MG resistance and MG stimulation of azole resistance. We propose endogenous and host-derived MG can induce MDR1 and other Mrr1-regulated genes causing increased drug resistance, which may contribute to some instances of fungal treatment failure.
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Affiliation(s)
- Amy R Biermann
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, NH, USA
| | - Elora G Demers
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, NH, USA
| | - Deborah A Hogan
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, NH, USA
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Análisis cuantitativo de la expresión de genes de resistencia a fluconazol en cepas de Candida albicans aisladas al ingreso de adultos mayores a una unidad de cuidados intensivos de Manizales, Colombia. BIOMÉDICA 2020; 40:153-165. [PMID: 32220171 PMCID: PMC7357389 DOI: 10.7705/biomedica.4723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Indexed: 11/21/2022]
Abstract
Introducción. Las infecciones oportunistas asociadas con Candida albicans han tenido gran repercusión en la salud pública por la mortalidad que generan en determinados grupos poblacionales. Aunque existen tratamientos farmacológicos disponibles, es evidente el aumento de la resistencia desarrollada por el agente patógeno, por lo que la determinación de los mecanismos de resistencia de las cepas presentes en las áreas hospitalarias es importante, ya que permitiría plantear mejores esquemas de tratamiento. Objetivo. Analizar la expresión de los genes ERG11, CDR1 y MDR1 en cepas de C. albicans aisladas de adultos mayores a su ingreso en la unidad de cuidados intensivos del Hospital Santa Sofía de Manizales, Colombia. Materiales y métodos. Se seleccionaron 29 muestras (21 resistentes y 8 sensibles) y se conformaron dos grupos de trabajo, uno de muestras con exposición al fluconazol y el otro sin esta. El ARN extraído se cuantificó mediante reacción en cadena de la polimerasa con transcriptasa inversa en tiempo real (RT-qPCR). Resultados. Se encontraron diferencias significativas en la expresión del gen MDR1 en el grupo de cepas de C. albicans resistentes. Dos de las cepas resistentes (104 y 62-2) expuestas al antifúngico presentaron valores muy elevados en la expresión de este gen. La expresión del ERG11 y del CDR1 no fue significativa en los grupos estudiados. Conclusión. El aumento de sobreexpresión del gen MDR1 indica que este puede ser el responsable de la resistencia; sin embargo, algunas cepas resistentes no sobreexpresaron los genes analizados, lo que indica que puede haber otros genes involucrados en la resistencia de las cepas estudiadas.
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Silva LN, de Mello TP, de Souza Ramos L, Branquinha MH, Dos Santos ALS. New and Promising Chemotherapeutics for Emerging Infections Involving Drug-resistant Non-albicans Candida Species. Curr Top Med Chem 2020; 19:2527-2553. [PMID: 31654512 DOI: 10.2174/1568026619666191025152412] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 02/13/2019] [Accepted: 02/16/2019] [Indexed: 02/06/2023]
Abstract
Fungal infections are a veritable public health problem worldwide. The increasing number of patient populations at risk (e.g. transplanted individuals, cancer patients, and HIV-infected people), as well as the use of antifungal agents for prophylaxis in medicine, have favored the emergence of previously rare or newly identified fungal species. Indeed, novel antifungal resistance patterns have been observed, including environmental sources and the emergence of simultaneous resistance to different antifungal classes, especially in Candida spp., which are known for the multidrug-resistance (MDR) profile. In order to circumvent this alarming scenario, the international researchers' community is engaged in discovering new, potent, and promising compounds to be used in a near future to treat resistant fungal infections in hospital settings on a global scale. In this context, many compounds with antifungal action from both natural and synthetic sources are currently under clinical development, including those that target either ergosterol or β(1,3)-D-glucan, presenting clear evidence of pharmacologic/pharmacokinetic advantages over currently available drugs against these two well-known fungal target structures. Among these are the tetrazoles VT-1129, VT-1161, and VT-1598, the echinocandin CD101, and the glucan synthase inhibitor SCY-078. In this review, we compiled the most recent antifungal compounds that are currently in clinical trials of development and described the potential outcomes against emerging and rare Candida species, with a focus on C. auris, C. dubliniensis, C. glabrata, C. guilliermondii, C. haemulonii, and C. rugosa. In addition to possibly overcoming the limitations of currently available antifungals, new investigational chemical agents that can enhance the classic antifungal activity, thereby reversing previously resistant phenotypes, were also highlighted. While novel and increasingly MDR non-albicans Candida species continue to emerge worldwide, novel strategies for rapid identification and treatment are needed to combat these life-threatening opportunistic fungal infections.
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Affiliation(s)
- Laura Nunes Silva
- Laboratorio de Estudos Avancados de Microrganismos Emergentes e Resistentes, Departamento de Microbiologia Geral, Instituto de Microbiologia Paulo de Goes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Thaís Pereira de Mello
- Laboratorio de Estudos Avancados de Microrganismos Emergentes e Resistentes, Departamento de Microbiologia Geral, Instituto de Microbiologia Paulo de Goes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Lívia de Souza Ramos
- Laboratorio de Estudos Avancados de Microrganismos Emergentes e Resistentes, Departamento de Microbiologia Geral, Instituto de Microbiologia Paulo de Goes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Marta Helena Branquinha
- Laboratorio de Estudos Avancados de Microrganismos Emergentes e Resistentes, Departamento de Microbiologia Geral, Instituto de Microbiologia Paulo de Goes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - André Luis Souza Dos Santos
- Laboratorio de Estudos Avancados de Microrganismos Emergentes e Resistentes, Departamento de Microbiologia Geral, Instituto de Microbiologia Paulo de Goes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.,Programa de Pós-Graduação em Bioquímica, Instituto de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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Liu N, Wu S, Dawood DH, Tang G, Zhang C, Liang J, Chen Y, Ma Z. The b-ZIP transcription factor FgTfmI is required for the fungicide phenamacril tolerance and pathogenecity in Fusarium graminearum. PEST MANAGEMENT SCIENCE 2019; 75:3312-3322. [PMID: 31025482 DOI: 10.1002/ps.5454] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 04/22/2019] [Accepted: 04/22/2019] [Indexed: 06/09/2023]
Abstract
BACKGROUND Fusarium head blight (FHB) is a devastating disease of cereal crops worldwide mainly caused by Fusarium graminearum. Due to the unavailability of FHB-resistant wheat cultivars, chemical fungicide application is currently the most effective approach for controlling FHB now. In the last few years, a novel cyanoacrylate fungicide, phenamacril, has been widely used in China for FHB disease management. In previous studies, we identified that myosin I (FgMyo1) is the target of phenamacril and is essential for mycotoxin deoxynivalenol (DON) biosynthesis and fungal growth. However, the regulation of FgMYO1 gene expression is still largely unknown. RESULTS In this study, we identified a b-ZIP transcription factor, FgTfmI, which regulates the mRNA expression of FgMYO1 upon phenamacril treatment. The FgTfmI directly binds to the promoter region of FgMYO1, and is required for the upregulation of FgMYO1 in response to phenamacril treatment. The deletion mutant of FgTFMI (ΔFgTfmI) displayed a slight growth defect, while it showed hypersensitivity to phenamacril, but not to other tested fungicides. FgTfmI also contributed to DON biosynthesis and the infection process in planta. CONCLUSIONS The transcription factor FgTfmI plays an important role in regulating transcription of the genes involved in phenamacril tolerance, DON biosynthesis and virulence in F. graminearum. © 2019 Society of Chemical Industry.
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Affiliation(s)
- Na Liu
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
- Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Zhejiang University, Hangzhou, China
| | - Siqi Wu
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
- Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Zhejiang University, Hangzhou, China
| | - Dawood H Dawood
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
- Department of Agriculture Chemistry, Faculty of Agriculture, Mansoura University, Mansoura, Egypt
| | - Guangfei Tang
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
- Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Zhejiang University, Hangzhou, China
| | - Chengqi Zhang
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Jingting Liang
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Yun Chen
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
- Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Zhejiang University, Hangzhou, China
| | - Zhonghua Ma
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
- Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Zhejiang University, Hangzhou, China
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Moreno A, Banerjee A, Prasad R, Falson P. PDR-like ABC systems in pathogenic fungi. Res Microbiol 2019; 170:417-425. [PMID: 31562919 DOI: 10.1016/j.resmic.2019.09.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 09/12/2019] [Accepted: 09/16/2019] [Indexed: 01/23/2023]
Abstract
ABC transporters of the Pleiotropic Drug Resistance (PDR) family are the main actors of antifungal resistance in pathogenic fungi. While their involvement in clinical resistant strains has been proven, their transport mechanism remains unclear. Notably, one hallmark of PDR transporters is their asymmetry, with one canonical nucleotide-binding site capable of ATP hydrolysis while the other site is not. Recent publications reviewed here show that the so-called "deviant" site is of crucial importance for drug transport and is a step towards alleviating the mystery around the existence of non-catalytic binding sites.
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Affiliation(s)
- Alexis Moreno
- Drug Resistance & Membrane Proteins Group, Molecular Microbiology and Structural Biochemistry Laboratory, CNRS-Lyon 1 University Research Lab n° 5086, Institut de Biologie et Chimie des Protéines, Lyon, France.
| | - Atanu Banerjee
- Amity Institute of Biotechnology and Amity Institute of Integrative Sciences and Health, Amity University Haryana, Gurgaon, India.
| | - Rajendra Prasad
- Amity Institute of Biotechnology and Amity Institute of Integrative Sciences and Health, Amity University Haryana, Gurgaon, India.
| | - Pierre Falson
- Drug Resistance & Membrane Proteins Group, Molecular Microbiology and Structural Biochemistry Laboratory, CNRS-Lyon 1 University Research Lab n° 5086, Institut de Biologie et Chimie des Protéines, Lyon, France.
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Evolution of drug resistance in an antifungal-naive chronic Candida lusitaniae infection. Proc Natl Acad Sci U S A 2018; 115:12040-12045. [PMID: 30389707 PMCID: PMC6255150 DOI: 10.1073/pnas.1807698115] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Management of the limited number of antimicrobials currently available requires the identification of infections that contain drug-resistant isolates and the discovery of factors that promote the evolution of drug resistance. Here, we report a single fungal infection in which we have identified numerous subpopulations that differ in their alleles of a single gene that impacts drug resistance. The diversity at this locus was markedly greater than the reported heterogeneity of alleles conferring antibiotic resistance in bacterial infections. Analysis of genomes from hundreds of Clavispora (Candida) lusitaniae isolates, through individual and pooled isolate sequencing, from a single individual with cystic fibrosis revealed at least 25 nonsynonymous mutations in MRR1, which encodes a transcription factor capable of inducing fluconazole (FLZ) resistance in Candida species. Isolates with high-activity Mrr1 variants were resistant to FLZ due to elevated expression of the MDR1-encoded efflux pump. We found that high Mrr1-regulated Mdr1 activity protected against host and bacterial factors, suggesting drug resistance can be selected for indirectly and perhaps explaining the Mrr1 heterogeneity in this individual who had no prior azole exposure. Regional analysis of C. lusitaniae populations from the upper and lower lobes of the right lung suggested intermingling of subpopulations throughout. Our retrospective characterization of sputum and lung populations by pooled sequencing found that alleles that confer FLZ resistance were a minority in each pool, possibly explaining why they were undetected before unsuccessful FLZ therapy. New susceptibility testing regimes may detect problematical drug-resistant subpopulations in heterogeneous single-species infections.
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Bayraktar S, Duran N, Duran GG, Eryilmaz N, Aslan H, Önlen C, Özer B. Identification of medically important Candida species by polymerase chain reaction-restriction fragment length polymorphism analysis of the rDNA ITS1 and ITS2 regions. Indian J Med Microbiol 2018; 35:535-542. [PMID: 29405146 DOI: 10.4103/ijmm.ijmm_17_102] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
AIM We aimed to identify the distribution of species in candidal strains isolated from clinical samples and restriction fragment length polymorphism (RFLP) method based on Msp I and Bln I restrictive enzyme cuts of polymerase chain reaction (PCR) products after the amplification of ITS1 and ITS2 regions of rDNA genotypically. MATERIALS AND METHODS One hundred and fifty candidal strains isolated from various clinical samples were studies/ included. Phenotypic species assessment was performed using automated VITEK-2 system and kit used with the biochemical tests. Common genomic region amplification peculiar to candidal strains was carried out using ITS1 and ITS2 primer pairs. After the amplification, PCR products were cut with Msp I and Bln I restriction enzymes for species identification. RESULTS The majority of Candida isolates were isolated from urine (78.6%) while other isolates were composed of strains isolated from swab, wound, blood and other samples by 11.3%, 3.3%, 2% and 4.7%, respectively. The result of RFLP analysis carried out with Msp I and Bln I restriction enzymes showed that candidal strains were Candida albicans by 45.3%, Candida glabrata by 19.3%, Candida tropicalis by 14.6%, Candida parapsilosis by 5.3%, Candida krusei by 5.3%, Candida lusitaniae by 0.6% and other candidal strains by 9.3%. CONCLUSION When the ability to identify Candida to species level of phenotypic and PCR-RFLP methods was assessed, a great difference was found between these two methods. It may be argued that Msp I and Bln I restriction enzyme fragments can be used in the identification of medically important Candida species. Further studies are needed to develop this kind of restriction profile to be used in the identification of candidal strains.
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Affiliation(s)
- Suphi Bayraktar
- Department of Microbiology, Medical Faculty, Mustafa Kemal University, Hatay, Turkey
| | - Nizami Duran
- Department of Microbiology, Medical Faculty, Mustafa Kemal University, Hatay, Turkey
| | - Gülay Gülbol Duran
- Department of Medical Biology, Medical Faculty, Mustafa Kemal University, Hatay, Turkey
| | - Naciye Eryilmaz
- Department of Microbiology, Medical Faculty, Mustafa Kemal University, Hatay, Turkey
| | - Hayat Aslan
- Department of Microbiology, Medical Faculty, Mustafa Kemal University, Hatay, Turkey
| | - Cansu Önlen
- Department of Microbiology, Medical Faculty, Mustafa Kemal University, Hatay, Turkey
| | - Burçin Özer
- Department of Microbiology, Medical Faculty, Mustafa Kemal University, Hatay, Turkey
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Host-Pathogen Interactions Mediated by MDR Transporters in Fungi: As Pleiotropic as it Gets! Genes (Basel) 2018; 9:genes9070332. [PMID: 30004464 PMCID: PMC6071111 DOI: 10.3390/genes9070332] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 06/21/2018] [Accepted: 06/27/2018] [Indexed: 12/12/2022] Open
Abstract
Fungal infections caused by Candida, Aspergillus, and Cryptococcus species are an increasing problem worldwide, associated with very high mortality rates. The successful prevalence of these human pathogens is due to their ability to thrive in stressful host niche colonization sites, to tolerate host immune system-induced stress, and to resist antifungal drugs. This review focuses on the key role played by multidrug resistance (MDR) transporters, belonging to the ATP-binding cassette (ABC), and the major facilitator superfamilies (MFS), in mediating fungal resistance to pathogenesis-related stresses. These clearly include the extrusion of antifungal drugs, with C. albicans CDR1 and MDR1 genes, and corresponding homologs in other fungal pathogens, playing a key role in this phenomenon. More recently, however, clues on the transcriptional regulation and physiological roles of MDR transporters, including the transport of lipids, ions, and small metabolites, have emerged, linking these transporters to important pathogenesis features, such as resistance to host niche environments, biofilm formation, immune system evasion, and virulence. The wider view of the activity of MDR transporters provided in this review highlights their relevance beyond drug resistance and the need to develop therapeutic strategies that successfully face the challenges posed by the pleiotropic nature of these transporters.
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Targeting Candida spp. to develop antifungal agents. Drug Discov Today 2018; 23:802-814. [PMID: 29353694 DOI: 10.1016/j.drudis.2018.01.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Revised: 12/09/2017] [Accepted: 01/04/2018] [Indexed: 01/15/2023]
Abstract
Invasive fungal infections are a complex challenge throughout the world because of their high incidence, mainly in critically ill patients, and high mortality rates. The antifungal agents currently available are limited; thus, there is a need for the rapid development of new drugs. In silico methods are a modern strategy to explore interactions between new compounds and specific fungal targets, but they depend on precise genetic information. Here, we discuss the main Candida spp. target genes, including information about null mutants, virulence, cytolocalization, co-regulatory genes, and compounds that are related to protein expression. These data will provide a basis for the future in silico development of antifungal drugs.
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15
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Detection of Cryptic Candida Species Recognized as Human Pathogens Through Molecular Biology Techniques. CURRENT FUNGAL INFECTION REPORTS 2017. [DOI: 10.1007/s12281-017-0294-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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16
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Resistance to antifungal therapies. Essays Biochem 2017; 61:157-166. [DOI: 10.1042/ebc20160067] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 01/02/2017] [Accepted: 01/05/2017] [Indexed: 11/17/2022]
Abstract
The evolution of antifungal resistance among fungal pathogens has rendered the limited arsenal of antifungal drugs futile. Considering the recent rise in the number of nosocomial fungal infections in immunocompromised patients, the emerging clinical multidrug resistance (MDR) has become a matter of grave concern for medical professionals. Despite advances in therapeutic interventions, it has not yet been possible to devise convincing strategies to combat antifungal resistance. Comprehensive understanding of the molecular mechanisms of antifungal resistance is essential for identification of novel targets that do not promote or delay emergence of drug resistance. The present study discusses features and limitations of the currently available antifungals, mechanisms of antifungal resistance and highlights the emerging therapeutic strategies that could be deployed to combat MDR.
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Abstract
Resistance to antifungal drugs is an increasingly significant clinical problem. The most common antifungal resistance encountered is efflux pump-mediated resistance of Candida species to azole drugs. One approach to overcome this resistance is to inhibit the pumps and chemosensitize resistant strains to azole drugs. Drug discovery targeting fungal efflux pumps could thus result in the development of azole-enhancing combination therapy. Heterologous expression of fungal efflux pumps in Saccharomyces cerevisiae provides a versatile system for screening for pump inhibitors. Fungal efflux pumps transport a range of xenobiotics including fluorescent compounds. This enables the use of fluorescence-based detection, as well as growth inhibition assays, in screens to discover compounds targeting efflux-mediated antifungal drug resistance. A variety of medium- and high-throughput screens have been used to identify a number of chemical entities that inhibit fungal efflux pumps.
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Hernando-Amado S, Blanco P, Alcalde-Rico M, Corona F, Reales-Calderón JA, Sánchez MB, Martínez JL. Multidrug efflux pumps as main players in intrinsic and acquired resistance to antimicrobials. Drug Resist Updat 2016; 28:13-27. [PMID: 27620952 DOI: 10.1016/j.drup.2016.06.007] [Citation(s) in RCA: 117] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 05/31/2016] [Accepted: 06/23/2016] [Indexed: 12/31/2022]
Abstract
Multidrug efflux pumps constitute a group of transporters that are ubiquitously found in any organism. In addition to other functions with relevance for the cell physiology, efflux pumps contribute to the resistance to compounds used for treating different diseases, including resistance to anticancer drugs, antibiotics or antifungal compounds. In the case of antimicrobials, efflux pumps are major players in both intrinsic and acquired resistance to drugs currently in use for the treatment of infectious diseases. One important aspect not fully explored of efflux pumps consists on the identification of effectors able to induce their expression. Indeed, whereas the analysis of clinical isolates have shown that mutants overexpressing these resistance elements are frequently found, less is known on the conditions that may trigger expression of efflux pumps, hence leading to transient induction of resistance in vivo, a situation that is barely detectable using classical susceptibility tests. In the current article we review the structure and mechanisms of regulation of the expression of bacterial and fungal efflux pumps, with a particular focus in those for which a role in clinically relevant resistance has been reported.
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Affiliation(s)
- Sara Hernando-Amado
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, CSIC, Darwin 3, Cantoblanco, 28049 Madrid, Spain
| | - Paula Blanco
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, CSIC, Darwin 3, Cantoblanco, 28049 Madrid, Spain
| | - Manuel Alcalde-Rico
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, CSIC, Darwin 3, Cantoblanco, 28049 Madrid, Spain
| | - Fernando Corona
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, CSIC, Darwin 3, Cantoblanco, 28049 Madrid, Spain
| | - Jose A Reales-Calderón
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, CSIC, Darwin 3, Cantoblanco, 28049 Madrid, Spain
| | - María B Sánchez
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, CSIC, Darwin 3, Cantoblanco, 28049 Madrid, Spain
| | - José L Martínez
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, CSIC, Darwin 3, Cantoblanco, 28049 Madrid, Spain.
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Assessing the potential of four cathelicidins for the management of mouse candidiasis and Candida albicans biofilms. Biochimie 2016; 121:268-77. [DOI: 10.1016/j.biochi.2015.11.028] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 11/29/2015] [Indexed: 11/22/2022]
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20
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Gonçalves SS, Souza ACR, Chowdhary A, Meis JF, Colombo AL. Epidemiology and molecular mechanisms of antifungal resistance in CandidaandAspergillus. Mycoses 2016; 59:198-219. [DOI: 10.1111/myc.12469] [Citation(s) in RCA: 112] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2015] [Revised: 12/14/2015] [Accepted: 12/18/2015] [Indexed: 12/15/2022]
Affiliation(s)
- Sarah Santos Gonçalves
- Laboratório Especial de Micologia, Disciplina de Infectologia, Escola Paulista de Medicina; Universidade Federal de São Paulo; São Paulo SP Brazil
| | - Ana Carolina Remondi Souza
- Laboratório Especial de Micologia, Disciplina de Infectologia, Escola Paulista de Medicina; Universidade Federal de São Paulo; São Paulo SP Brazil
| | - Anuradha Chowdhary
- Department of Medical Mycology; Vallabhbhai Patel Chest Institute; University of Delhi; Delhi India
| | - Jacques F. Meis
- Department of Medical Microbiology and Infectious Diseases; Canisius Wilhelmina Hospital; Nijmegen the Netherlands
- Department of Medical Microbiology; Radboud University Medical Centre; Nijmegen the Netherlands
| | - Arnaldo Lopes Colombo
- Laboratório Especial de Micologia, Disciplina de Infectologia, Escola Paulista de Medicina; Universidade Federal de São Paulo; São Paulo SP Brazil
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21
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Gonçalves C, Coelho MA, Salema-Oom M, Gonçalves P. Stepwise Functional Evolution in a Fungal Sugar Transporter Family. Mol Biol Evol 2015; 33:352-66. [DOI: 10.1093/molbev/msv220] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
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22
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Souza ACR, Fuchs BB, Pinhati HMS, Siqueira RA, Hagen F, Meis JF, Mylonakis E, Colombo AL. Candida parapsilosis Resistance to Fluconazole: Molecular Mechanisms and In Vivo Impact in Infected Galleria mellonella Larvae. Antimicrob Agents Chemother 2015; 59:6581-7. [PMID: 26259795 PMCID: PMC4576033 DOI: 10.1128/aac.01177-15] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 08/02/2015] [Indexed: 01/07/2023] Open
Abstract
Candida parapsilosis is the main non-albicans Candida species isolated from patients in Latin America. Mutations in the ERG11 gene and overexpression of membrane transporter proteins have been linked to fluconazole resistance. The aim of this study was to evaluate the molecular mechanisms in fluconazole-resistant strains of C. parapsilosis isolated from critically ill patients. The identities of the nine collected C. parapsilosis isolates at the species level were confirmed through molecular identification with a TaqMan qPCR assay. The clonal origin of the strains was checked by microsatellite typing. The Galleria mellonella infection model was used to confirm in vitro resistance. We assessed the presence of ERG11 mutations, as well as the expression of ERG11 and two additional genes that contribute to antifungal resistance (CDR1 and MDR1), by using real-time quantitative PCR. All of the C. parapsilosis (sensu stricto) isolates tested exhibited fluconazole MICs between 8 and 16 μg/ml. The in vitro data were confirmed by the failure of fluconazole in the treatment of G. mellonella infected with fluconazole-resistant strains of C. parapsilosis. Sequencing of the ERG11 gene revealed a common mutation leading to a Y132F amino acid substitution in all of the isolates, a finding consistent with their clonal origin. After fluconazole exposure, overexpression was noted for ERG11, CDR1, and MDR1 in 9/9, 9/9, and 2/9 strains, respectively. We demonstrated that a combination of molecular mechanisms, including the presence of point mutations in the ERG11 gene, overexpression of ERG11, and genes encoding efflux pumps, are involved in fluconazole resistance in C. parapsilosis.
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Affiliation(s)
- Ana Carolina R Souza
- Laboratório Especial de Micologia, Disciplina de Infectologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brazil
| | - Beth Burgwyn Fuchs
- Division of Infectious Diseases, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island, USA
| | - Henrique M S Pinhati
- Universidade de Brasília, Brasília, DF, Brazil Hospital Santa Luzia, Brasília, DF, Brazil
| | - Ricardo A Siqueira
- Laboratório Especial de Micologia, Disciplina de Infectologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brazil
| | - Ferry Hagen
- Department of Medical Microbiology and Infectious Diseases, Canisius-Wilhelmina Hospital, Nijmegen, Netherlands
| | - Jacques F Meis
- Department of Medical Microbiology and Infectious Diseases, Canisius-Wilhelmina Hospital, Nijmegen, Netherlands Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, Netherlands
| | - Eleftherios Mylonakis
- Division of Infectious Diseases, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island, USA
| | - Arnaldo L Colombo
- Laboratório Especial de Micologia, Disciplina de Infectologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brazil
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Optimization of submerged fermentation conditions for immunosuppressant mycophenolic acid production by Penicillium roqueforti isolated from blue-molded cheeses: enhanced production by ultraviolet and gamma irradiation. World J Microbiol Biotechnol 2014; 30:2625-38. [DOI: 10.1007/s11274-014-1685-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Accepted: 06/04/2014] [Indexed: 10/25/2022]
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24
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Phylogenetic and syntenic analyses of the 12-spanner drug:H(+) antiporter family 1 (DHA1) in pathogenic Candida species: evolution of MDR1 and FLU1 genes. Genomics 2014; 104:45-57. [PMID: 24907457 DOI: 10.1016/j.ygeno.2014.05.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Revised: 05/11/2014] [Accepted: 05/28/2014] [Indexed: 12/22/2022]
Abstract
Candida albicans and other pathogenic Candida species can develop resistance to clinical fungicides through active drug export mediated by multidrug efflux pumps, in particular by members of the drug:H(+) antiporter family 1 (DHA1). The DHA1 proteins encoded in the genomes of 31 hemiascomycetous strains from 25 species were identified and homology relationships between these proteins and the functionally characterised DHA1 in the model yeast Saccharomyces cerevisiae were established. Gene neighbourhood analysis allowed the reconstruction of sixteen DHA1 lineages conserved during the CTG complex species evolution. The evolutionary history of C. albicans MDR1 and FLU1 genes and Candida dubliniensis, Candida tropicalis and Candida parapsilosis MDR1 genes was detailed. Candida genomes show an abundant number of MDR1 and FLU1 homologues but the chromosome environment where MDR1 homologues reside was poorly conserved during evolution. Gene duplication and loss are major mechanisms underlying the evolution of the DHA1 genes in Candida species.
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25
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Costa C, Dias PJ, Sá-Correia I, Teixeira MC. MFS multidrug transporters in pathogenic fungi: do they have real clinical impact? Front Physiol 2014; 5:197. [PMID: 24904431 PMCID: PMC4035561 DOI: 10.3389/fphys.2014.00197] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Accepted: 05/09/2014] [Indexed: 11/16/2022] Open
Abstract
Infections caused by opportunistic fungal pathogens have reached concerning numbers due to the increase of the immunocrompromised human population and to the development of antifungal resistance. This resistance is often attributed to the action of multidrug efflux pumps, belonging to the ATP-binding cassette (ABC) superfamily and the major facilitator superfamily (MFS). Although many studies have focused on the role of ABC multidrug efflux transporters, little is still known on the part played by the Drug:H+ Antiporter (DHA) family of the MFS in this context. This review summarizes current knowledge on the role in antifungal drug resistance, mode of action and phylogenetic relations of DHA transporters, from the model yeast S. cerevisiae to pathogenic yeasts and filamentous fungi. Through the compilation of the predicted DHA transporters in the medically relevant Candida albicans, C. glabrata, C. parapsilosis, C. lusitaniae, C. tropicalis, C. guilliermondii, Cryptococcus neoformans, and Aspergillus fumigatus species, the fact that only 5% of the DHA transporters from these organisms have been characterized so far is evidenced. The role of these transporters in antifungal drug resistance and in pathogen-host interaction is described and their clinical relevance discussed. Given the knowledge gathered for these few DHA transporters, the need to carry out a systematic characterization of the DHA multidrug efflux pumps in fungal pathogens, with emphasis on their clinical relevance, is highlighted.
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Affiliation(s)
- Catarina Costa
- Biological Sciences Research Group, Department of Bioengineering, Instituto Superior Técnico, IBB - Institute for Biotechnology and Bioengineering, Universidade de Lisboa Lisbon, Portugal
| | - Paulo J Dias
- Biological Sciences Research Group, Department of Bioengineering, Instituto Superior Técnico, IBB - Institute for Biotechnology and Bioengineering, Universidade de Lisboa Lisbon, Portugal
| | - Isabel Sá-Correia
- Biological Sciences Research Group, Department of Bioengineering, Instituto Superior Técnico, IBB - Institute for Biotechnology and Bioengineering, Universidade de Lisboa Lisbon, Portugal
| | - Miguel C Teixeira
- Biological Sciences Research Group, Department of Bioengineering, Instituto Superior Técnico, IBB - Institute for Biotechnology and Bioengineering, Universidade de Lisboa Lisbon, Portugal
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26
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Soto SM. Role of efflux pumps in the antibiotic resistance of bacteria embedded in a biofilm. Virulence 2013; 4:223-9. [PMID: 23380871 PMCID: PMC3711980 DOI: 10.4161/viru.23724] [Citation(s) in RCA: 254] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2012] [Revised: 01/22/2013] [Accepted: 01/23/2013] [Indexed: 02/08/2023] Open
Abstract
Biofilms are complex microbial associations anchored to abiotic or biotic surfaces, embedded in extracellular matrix produced by the biofilms themselves where they interact with each other and the environment. One of the main properties of biofilms is their capacity to be more resistant to antimicrobial agents than planktonic cells. Efflux pumps have been reported as one of the mechanisms responsible for the antimicrobial resistance in biofilm structures. Evidence of the role of efflux pump in biofilm resistance has been found in several microorganisms such as Pseudomonas aeruginosa, Escherichia coli and Candida albicans. However, in spite of the studies on the importance of efflux pumps in biofilm growth and about their relevance in antimicrobial resistance forming biofilm, the exact role of these efflux systems has not been determined as yet.
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Affiliation(s)
- Sara M Soto
- Barcelona Centre for International Health Research (CRESIB, Hospital Clinic-University of Barcelona), Barcelona, Spain.
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27
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Armentano RA, Cooke KL, Wickes BL. Disseminated mycotic infection caused byWesterdykellaspecies in a German Shepherd Dog. J Am Vet Med Assoc 2013; 242:381-7. [DOI: 10.2460/javma.242.3.381] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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28
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Huang M, Kao KC. Population dynamics and the evolution of antifungal drug resistance in Candida albicans. FEMS Microbiol Lett 2012; 333:85-93. [PMID: 22540673 DOI: 10.1111/j.1574-6968.2012.02587.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Revised: 04/25/2012] [Accepted: 04/26/2012] [Indexed: 12/01/2022] Open
Abstract
Candida albicans is an important human fungal pathogen. Resistance to all major antifungal agents has been observed in clinical isolates of Candida spp. and is a major clinical challenge. The rise and expansion of drug-resistant mutants during exposure to antifungal agents occurs through a process of adaptive evolution, with potentially complex population dynamics. Understanding the population dynamics during the emergence of drug resistance is important for determining the fundamental principles of how fungal pathogens evolve for resistance. While few detailed reports that focus on the population dynamics of C. albicans currently exist, several important features on the population structure and adaptive landscape can be elucidated from existing evolutionary studies in in vivo and in vitro systems.
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Affiliation(s)
- Mian Huang
- Department of Chemical Engineering, Texas A&M University, College Station, TX 77843-3122, USA
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30
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Papon N, Courdavault V, Clastre M, Simkin AJ, Crèche J, Giglioli-Guivarc’h N. Deus ex Candida genetics: overcoming the hurdles for the development of a molecular toolbox in the CTG clade. Microbiology (Reading) 2012; 158:585-600. [DOI: 10.1099/mic.0.055244-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Nicolas Papon
- EA2106, Biomolécules et Biotechnologies Végétales, Université François-Rabelais de Tours, France
| | - Vincent Courdavault
- EA2106, Biomolécules et Biotechnologies Végétales, Université François-Rabelais de Tours, France
| | - Marc Clastre
- EA2106, Biomolécules et Biotechnologies Végétales, Université François-Rabelais de Tours, France
| | - Andrew J. Simkin
- EA2106, Biomolécules et Biotechnologies Végétales, Université François-Rabelais de Tours, France
| | - Joël Crèche
- EA2106, Biomolécules et Biotechnologies Végétales, Université François-Rabelais de Tours, France
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The monoamine oxidase A inhibitor clorgyline is a broad-spectrum inhibitor of fungal ABC and MFS transporter efflux pump activities which reverses the azole resistance of Candida albicans and Candida glabrata clinical isolates. Antimicrob Agents Chemother 2011; 56:1508-15. [PMID: 22203607 DOI: 10.1128/aac.05706-11] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Resistance to the commonly used azole antifungal fluconazole (FLC) can develop due to overexpression of ATP-binding cassette (ABC) and major facilitator superfamily (MFS) plasma membrane transporters. An approach to overcoming this resistance is to identify inhibitors of these efflux pumps. We have developed a pump assay suitable for high-throughput screening (HTS) that uses recombinant Saccharomyces cerevisiae strains hyperexpressing individual transporters from the opportunistic fungal pathogen Candida albicans. The recombinant strains possess greater resistance to azoles and other pump substrates than the parental host strain. A flow cytometry-based HTS, which measured increased intracellular retention of the fluorescent pump substrate rhodamine 6G (R6G) within yeast cells, was used to screen the Prestwick Chemical Library (PCL) of 1,200 marketed drugs. Nine compounds were identified as hits, and the monoamine oxidase A inhibitor (MAOI) clorgyline was identified as an inhibitor of two C. albicans ABC efflux pumps, CaCdr1p and CaCdr2p. Secondary in vitro assays confirmed inhibition of pump-mediated efflux by clorgyline. Clorgyline also reversed the FLC resistance of S. cerevisiae strains expressing other individual fungal ABC transporters (Candida glabrata Cdr1p or Candida krusei Abc1p) or the C. albicans MFS transporter Mdr1p. Recombinant strains were also chemosensitized by clorgyline to other azoles (itraconazole and miconazole). Importantly, clorgyline showed synergy with FLC against FLC-resistant C. albicans clinical isolates and a C. glabrata strain and inhibited R6G efflux from a FLC-resistant C. albicans clinical isolate. Clorgyline is a novel broad-spectrum inhibitor of two classes of fungal efflux pumps that acts synergistically with azoles against azole-resistant C. albicans and C. glabrata strains.
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Antifungal resistance and new strategies to control fungal infections. Int J Microbiol 2011; 2012:713687. [PMID: 22187560 PMCID: PMC3236459 DOI: 10.1155/2012/713687] [Citation(s) in RCA: 262] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Accepted: 09/06/2011] [Indexed: 11/28/2022] Open
Abstract
Despite improvement of antifungal therapies over the last 30 years, the phenomenon of antifungal resistance is still of major concern in clinical practice. In the last 10 years the molecular mechanisms underlying this phenomenon were extensively unraveled. In this paper, after a brief overview of currently available antifungals, molecular mechanisms of antifungal resistance will be detailed. It appears that major mechanisms of resistance are essential due to the deregulation of antifungal resistance effector genes. This deregulation is a consequence of point mutations occurring in transcriptional regulators of these effector genes. Resistance can also follow the emergence of point mutations directly in the genes coding antifungal targets. In addition we further describe new strategies currently undertaken to discover alternative therapy targets and antifungals. Identification of new antifungals is essentially achieved by the screening of natural or synthetic chemical compound collections. Discovery of new putative antifungal targets is performed through genome-wide approaches for a better understanding of the human pathogenic fungi biology.
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Huang M, McClellan M, Berman J, Kao KC. Evolutionary dynamics of Candida albicans during in vitro evolution. EUKARYOTIC CELL 2011; 10:1413-21. [PMID: 21890821 PMCID: PMC3209058 DOI: 10.1128/ec.05168-11] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Accepted: 08/22/2011] [Indexed: 12/29/2022]
Abstract
While mechanisms of resistance to major antifungal agents have been characterized in Candida albicans, little is known about the evolutionary trajectories during the emergence of drug resistance. Here, we examined the evolutionary dynamics of C. albicans that evolved in vitro in the presence or absence of fluconazole using the visualizing evolution in real-time (VERT) method, a novel experimental approach that facilitates the systematic isolation of adaptive mutants that arise in the population. We found an increase in the frequency of adaptive events in the presence of fluconazole compared to the no-drug controls. Analysis of the evolutionary dynamics revealed that mutations that led to increased drug resistance appeared frequently and that mutants with increased levels of resistance arose in independent lineages. Interestingly, most adaptive mutants with increased fitness in the presence of the drug did not exhibit a significant fitness decrease in the absence of the drug, supporting the idea that rapid resistance can arise from mutations in strains maintained in the population prior to exposure to the drug.
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Affiliation(s)
- Mian Huang
- Department of Chemical Engineering, Texas A&M University, College Station, Texas
| | - Mark McClellan
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota
| | - Judith Berman
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota
| | - Katy C. Kao
- Department of Chemical Engineering, Texas A&M University, College Station, Texas
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Diagnosis of Antifungal Drug Resistance Mechanisms in Fungal Pathogens: Transcriptional Gene Regulation. CURRENT FUNGAL INFECTION REPORTS 2011. [DOI: 10.1007/s12281-011-0055-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Borecká S, Pinjon E, Sullivan DJ, Kuchler K, Blaško J, Kulková N, Bujdáková H. Cdr2p contributes to fluconazole resistance in Candida dubliniensis clinical isolates. Can J Microbiol 2011; 57:416-26. [PMID: 21542785 DOI: 10.1139/w11-025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Abstract
The development of resistance to azole antifungals used in the treatment of fungal infections can be a serious medical problem. Here, we investigate the molecular mechanisms associated with reduced susceptibility to fluconazole in clinical isolates of Candida dubliniensis , showing evidence of the trailing growth phenomenon. The changes in membrane sterol composition were studied in the presence of subinhibitory fluconazole concentrations. Despite lanosterol and eburicol accumulating as the most prevalent sterols after fluconazole treatment, these ergosterol precursors still support growth of Candida isolates. The overexpression of ABC transporters was demonstrated by immunoblotting employing specific antibodies against Cdr1p and Cdr2p. The presence of a full-length 170 kDa protein Cdr1p was detected in two isolates, while a truncated form of Cdr1p with the molecular mass of 85 kDa was observed in isolate 966/3(2). Notably, Cdr2p was detected in this isolate, and the expression of this transporter was modulated by subinhibitory concentrations of fluconazole. These results suggest that C. dubliniensis can display the trailing growth phenomenon, and such isolates express similar molecular mechanisms like that of fluconazole-resistant isolates and can therefore be associated with recurrent infections.
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Affiliation(s)
- Silvia Borecká
- Comenius University in Bratislava, Department of Microbiology and Virology, Mlynská dolina, Bratislava, Slovak Republic
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Coleman DC, Moran GP, McManus BA, Sullivan DJ. Mechanisms of antifungal drug resistance in Candida dubliniensis. Future Microbiol 2010; 5:935-49. [PMID: 20521937 DOI: 10.2217/fmb.10.51] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Candida dubliniensis was first described in 1995 and is the most closely related species to the predominant human fungal pathogen Candida albicans. C. dubliniensis is significantly less prevalent and less pathogenic than C. albicans and is primarily associated with infections in HIV-infected individuals and other immunocompromised cohorts. The population structure of C. dubliniensis consists of three well-defined major clades and is significantly less diverse than C. albicans. The majority of C. dubliniensis isolates are susceptible to antifungal drugs commonly used to treat Candida infections. To date only two major patterns of antifungal drug resistance have been identified and the molecular mechanisms of these are very similar to the resistance mechanisms that have been described previously in C. albicans. However, significant differences are evident in the predominant antifungal drug mechanisms employed by C. dubliniensis, differences that reflect its more clonal nature, its lower prevalence and characteristics of its genome, the complete sequence of which has only recently been determined.
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Affiliation(s)
- David C Coleman
- Microbiology Research Unit, Division of Oral Biosciences, Dublin Dental School & Hospital, University of Dublin, Trinity College Dublin, Dublin 2, Republic of Ireland.
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Barker KS, Rogers PD. Recent insights into the mechanisms of antifungal resistance. Curr Infect Dis Rep 2010; 8:449-56. [PMID: 17064638 DOI: 10.1007/s11908-006-0019-3] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The incidence of fungal infections has increased in recent years, particularly among immunocompromised individuals. Treatment of invasive fungal infections has been hampered by a limited number of available antifungal agents and both intrinsic and acquired resistance to these agents among many fungal pathogens. Therefore, much interest has focused on elucidating the molecular basis for antifungal resistance. Recent efforts have increased our understanding of this process, including the transcriptional regulation of azole resistance in Candida spp, mechanisms of intrinsic resistance to amphotericin B, and mechanisms of acquired resistance to the new echinocandin class of antifungal agents. This review discusses these and other newly clarified resistance mechanisms, as well as the direction of future antifungal resistance research. Despite these advances, undiscovered resistance determinants exist, and resistance to newer agents likely will continue to emerge.
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Affiliation(s)
- Katherine S Barker
- Room 304 West Patient Tower, LeBonheur Children's Medical Center, 50 North Dunlap Street, Memphis, TN 38103, USA
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38
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Morschhäuser J. Regulation of multidrug resistance in pathogenic fungi. Fungal Genet Biol 2010; 47:94-106. [DOI: 10.1016/j.fgb.2009.08.002] [Citation(s) in RCA: 215] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2009] [Revised: 07/21/2009] [Accepted: 08/02/2009] [Indexed: 12/21/2022]
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Sanglard D, Coste A, Ferrari S. Antifungal drug resistance mechanisms in fungal pathogens from the perspective of transcriptional gene regulation. FEMS Yeast Res 2009; 9:1029-50. [PMID: 19799636 DOI: 10.1111/j.1567-1364.2009.00578.x] [Citation(s) in RCA: 179] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Fungi are primitive eukaryotes and have adapted to a variety of niches during evolution. Some fungal species may interact with other life forms (plants, insects, mammals), but are considered as pathogens when they cause mild to severe diseases. Chemical control strategies have emerged with the development of several drugs with antifungal activity against pathogenic fungi. Antifungal agents have demonstrated their efficacy by improving patient health in medicine. However, fungi have counteracted antifungal agents in several cases by developing resistance mechanisms. These mechanisms rely on drug resistance genes including multidrug transporters and drug targets. Their regulation is crucial for the development of antifungal drug resistance and therefore transcriptional factors critical for their regulation are being characterized. Recent genome-wide studies have revealed complex regulatory circuits involving these genetic and transcriptional regulators. Here, we review the current understanding of the transcriptional regulation of drug resistance genes from several fungal pathogens including Candida and Aspergillus species.
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Affiliation(s)
- Dominique Sanglard
- Institute of Microbiology, University of Lausanne and University Hospital Center, 1011 Lausanne, Switzerland.
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40
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Abstract
Pathogens must be able to overcome both host defenses and antimicrobial treatment in order to successfully infect and maintain colonization of the host. One way fungi accomplish this feat and overcome intercellular toxin accumulation is efflux pumps, in particular ATP-binding cassette transporters and transporters of the major facilitator superfamily. Members of these two superfamilies remove many toxic compounds by coupling transport with ATP hydrolysis or a proton gradient, respectively. Fungal genomes encode a plethora of members of these families of transporters compared to other organisms. In this review we discuss the role these two fungal superfamilies of transporters play in virulence and resistance to antifungal agents. These efflux transporters are responsible not only for export of compounds involved in pathogenesis such as secondary metabolites, but also export of host-derived antimicrobial compounds. In addition, we examine the current knowledge of these transporters in resistance of pathogens to clinically relevant antifungal agents.
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Affiliation(s)
- Jeffrey J. Coleman
- Division of Infectious Diseases, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Eleftherios Mylonakis
- Division of Infectious Diseases, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
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41
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Alani F, Grove JA, Anderson WA, Moo-Young M. Mycophenolic acid production in solid-state fermentation using a packed-bed bioreactor. Biochem Eng J 2009. [DOI: 10.1016/j.bej.2008.11.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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42
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Diwischek F, Morschhäuser J, Holzgrabe U. Cerulenin analogues as inhibitors of efflux pumps in drug-resistant Candida albicans. Arch Pharm (Weinheim) 2009; 342:150-64. [PMID: 19253321 DOI: 10.1002/ardp.200800160] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Overexpression of the ABC transporters Cdr1 and Cdr2 or the major facilitator Mdr1 causes multidrug resistance in the human fungal pathogen Candida albicans. The fatty acid synthesis inhibitor cerulenin and the structurally unrelated Golgi transport inhibitor brefeldin A are substrates for both types of efflux pumps in Candida albicans. In an effort to overcome efflux pump-mediated drug resistance in Candida albicans, cerulenin analogues were generated using a variety of synthesis pathways. The so obtained cerulenin derivatives were tested on multidrug-resistant Candida albicans isolates which constitutively overexpress either Mdr1 or Cdr1 and Cdr2. Some of these compounds were found to decrease Mdr1-mediated resistance to brefeldin A up to eightfold compared to the control.
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Affiliation(s)
- Florian Diwischek
- Institut für Pharmazie und Lebensmittelchemie, Universität Würzburg, Würzburg, Germany
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43
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Sá-Correia I, dos Santos SC, Teixeira MC, Cabrito TR, Mira NP. Drug:H+ antiporters in chemical stress response in yeast. Trends Microbiol 2008; 17:22-31. [PMID: 19062291 DOI: 10.1016/j.tim.2008.09.007] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2008] [Revised: 08/03/2008] [Accepted: 09/19/2008] [Indexed: 10/21/2022]
Abstract
The emergence of widespread multidrug resistance (MDR) is a serious challenge for therapeutics, food-preservation and crop protection. Frequently, MDR is a result of the action of drug-efflux pumps, which are able to catalyze the extrusion of unrelated chemical compounds. This review summarizes the current knowledge on the Saccharomyces cerevisiae drug:H+ antiporters of the major facilitator superfamily (MFS), a group of MDR transporters that is still characterized poorly in eukaryotes. Particular focus is given here to the physiological role and expression regulation of these transporters, while we provide a unified view of new data emerging from functional genomics approaches. Although traditionally described as drug pumps, evidence reviewed here corroborates the hypothesis that several MFS-MDR transporters might have a natural substrate and that drug transport might occur only fortuitously or opportunistically. Their role in MDR might even result from the transport of endogenous metabolites that affect the partition of cytotoxic compounds indirectly. Finally, the extrapolation of the gathered knowledge on the MDR phenomenon in yeast to pathogenic fungi and higher eukaryotes is discussed.
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Affiliation(s)
- Isabel Sá-Correia
- Institute for Biotechnology and Bioengineering, Centre for Biological and Chemical Engineering, Instituto Superior Técnico, 1049-001 Lisboa, Portugal.
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Gain-of-function mutations in the transcription factor MRR1 are responsible for overexpression of the MDR1 efflux pump in fluconazole-resistant Candida dubliniensis strains. Antimicrob Agents Chemother 2008; 52:4274-80. [PMID: 18809934 DOI: 10.1128/aac.00740-08] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Candida dubliniensis, a yeast that is closely related to Candida albicans, can rapidly develop resistance to the commonly used antifungal agent fluconazole in vitro and in vivo during antimycotic therapy. Fluconazole resistance in C. dubliniensis is usually caused by constitutive overexpression of the MDR1 gene, which encodes a multidrug efflux pump of the major facilitator superfamily. The zinc cluster transcription factor Mrr1p has recently been shown to control MDR1 expression in C. albicans in response to inducing stimuli, and gain-of-function mutations in the MRR1 gene result in constitutive upregulation of the MDR1 efflux pump. We identified a gene with a high degree of similarity to C. albicans MRR1 (CaMRR1) in the C. dubliniensis genome sequence. When C. dubliniensis MRR1 (CdMRR1) was expressed in C. albicans mrr1Delta mutants, it restored benomyl-inducible MDR1 expression, demonstrating that CdMRR1 is the ortholog of CaMRR1. To investigate whether MDR1 overexpression in C. dubliniensis is caused by mutations in MRR1, we sequenced the MRR1 alleles from a fluconazole-resistant, clinical C. dubliniensis isolate and a matched, fluconazole-susceptible isolate from the same patient as well as those from four in vitro-generated, fluconazole-resistant C. dubliniensis strains derived from two different C. dubliniensis isolates. We found that all five resistant strains contained single nucleotide substitutions or small in-frame deletions that resulted in amino acid changes in Mrr1p. Expression of these mutated alleles in C. albicans resulted in the constitutive activation of the MDR1 promoter and multidrug resistance. Therefore, mutations in MRR1 are the major cause of MDR1 upregulation in both C. albicans and C. dubliniensis, demonstrating that the transcription factor Mrr1p plays a central role in the development of drug resistance in these human fungal pathogens.
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45
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Borecká-Melkusová S, Moran GP, Sullivan DJ, Kucharíková S, Chorvát D, Bujdáková H. The expression of genes involved in the ergosterol biosynthesis pathway in Candida albicans and Candida dubliniensis biofilms exposed to fluconazole. Mycoses 2008; 52:118-28. [PMID: 18627475 DOI: 10.1111/j.1439-0507.2008.01550.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The expression of the ERG1, ERG3, ERG7, ERG9, ERG11 and ERG25 genes in response to incubation with fluconazole and biofilm formation was investigated using reverse-transcription PCR and real-time PCR in Candida albicans and Candida dubliniensis clinical isolates. The viability of biofilm was measured using an 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) reduction assay and confocal scanning laser microscopy (CSLM). Expression of the ERG11 gene was found to be low or moderate and it was regulated by fluconazole addition more so than by biofilm formation. Very low or non-detectable expression of ERG1, ERG7 and ERG25 genes was detected in C. albicans. The expression of the ERG9 increased in the presence of fluconazole in some isolates. Following incubation with fluconazole, formation of biofilm by C. dubliniensis was coupled with up-regulation of the ERG3 and ERG25 genes as have been observed previously in C. albicans. Planktonic cells of both Candida species released from biofilm displayed similar resistance mechanisms to fluconazole like attached cells. The XTT reduction assay and CSLM revealed that although incubation with fluconazole decreased the biofilm thickness, these were still comprised metabolically active cells able to disseminate and produce biofilm. Our data indicate that biofilm represents a highly adapted community reflecting the individuality of clinical isolates.
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Affiliation(s)
- Silvia Borecká-Melkusová
- Department of Microbiology and Virology, Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia.
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46
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Dunkel N, Blass J, Rogers PD, Morschhäuser J. Mutations in the multi-drug resistance regulator MRR1, followed by loss of heterozygosity, are the main cause of MDR1 overexpression in fluconazole-resistant Candida albicans strains. Mol Microbiol 2008; 69:827-40. [PMID: 18577180 DOI: 10.1111/j.1365-2958.2008.06309.x] [Citation(s) in RCA: 191] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Overexpression of the MDR1 gene, encoding a multi-drug efflux pump of the major facilitator superfamily, is a major cause of resistance to the widely used antifungal agent fluconazole and other toxic substances in the fungal pathogen Candida albicans. We found that all tested clinical and in vitro generated C. albicans strains that had become fluconazole-resistant by constitutive MDR1 upregulation contained mutations in the MRR1 gene, which encodes a transcription factor that controls MDR1 expression. Introduction of the mutated alleles into a drug-susceptible C. albicans strain resulted in activation of the MDR1 promoter and multi-drug resistance, confirming that the amino acid substitutions in Mrr1p were gain-of-function mutations that rendered the transcription factor constitutively active. The majority of the MDR1 overexpressing strains had become homozygous for the mutated MRR1 alleles, demonstrating that the increased resistance level conferred by two gain-of-function alleles provides sufficient advantage to select for the loss of heterozygosity in the presence of fluconazole both in vitro and within the human host during therapy. Loss of heterozygosity usually occurred by mitotic recombination between the two chromosome 3 homologues on which MRR1 is located, but evidence for complete loss of one chromosome and duplication of the chromosome containing the mutated MRR1 allele was also obtained in two in vitro generated fluconazole-resistant strains. These results demonstrate that gain-of-function mutations in MRR1 are the major, if not the sole, mechanism of MDR1 overexpression in fluconazole-resistant strains and that this transcription factor plays a central role in the development of drug resistance in C. albicans.
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Affiliation(s)
- Nico Dunkel
- Institut für Molekulare Infektionsbiologie, Universität Würzburg, Würzburg, Germany
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47
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Morschhäuser J, Barker KS, Liu TT, BlaB-Warmuth J, Homayouni R, Rogers PD. The transcription factor Mrr1p controls expression of the MDR1 efflux pump and mediates multidrug resistance in Candida albicans. PLoS Pathog 2008; 3:e164. [PMID: 17983269 PMCID: PMC2048531 DOI: 10.1371/journal.ppat.0030164] [Citation(s) in RCA: 241] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2007] [Accepted: 09/20/2007] [Indexed: 11/18/2022] Open
Abstract
Constitutive overexpression of the MDR1 (multidrug resistance) gene, which encodes a multidrug efflux pump of the major facilitator superfamily, is a frequent cause of resistance to fluconazole and other toxic compounds in clinical Candida albicans strains, but the mechanism of MDR1 upregulation has not been resolved. By genome-wide gene expression analysis we have identified a zinc cluster transcription factor, designated as MRR1 (multidrug resistance regulator), that was coordinately upregulated with MDR1 in drug-resistant, clinical C. albicans isolates. Inactivation of MRR1 in two such drug-resistant isolates abolished both MDR1 expression and multidrug resistance. Sequence analysis of the MRR1 alleles of two matched drug-sensitive and drug-resistant C. albicans isolate pairs showed that the resistant isolates had become homozygous for MRR1 alleles that contained single nucleotide substitutions, resulting in a P683S exchange in one isolate and a G997V substitution in the other isolate. Introduction of these mutated alleles into a drug-susceptible C. albicans strain resulted in constitutive MDR1 overexpression and multidrug resistance. By comparing the transcriptional profiles of drug-resistant C. albicans isolates and mrr1Δ mutants derived from them and of C. albicans strains carrying wild-type and mutated MRR1 alleles, we defined the target genes that are controlled by Mrr1p. Many of the Mrr1p target genes encode oxidoreductases, whose upregulation in fluconazole-resistant isolates may help to prevent cell damage resulting from the generation of toxic molecules in the presence of fluconazole and thereby contribute to drug resistance. The identification of MRR1 as the central regulator of the MDR1 efflux pump and the elucidation of the mutations that have occurred in fluconazole-resistant, clinical C. albicans isolates and result in constitutive activity of this trancription factor provide detailed insights into the molecular basis of multidrug resistance in this important human fungal pathogen. The Candida albicans MDR1 (multidrug resistance) gene encodes a multidrug efflux pump of the major facilitator superfamily that is constitutively overexpressed in many fluconazole-resistant strains. Although MDR1 overexpression is a major cause of resistance to this widely used antifungal agent and other metabolic inhibitors, so far the molecular basis of MDR1 upregulation in resistant strains has remained elusive. By comparing the transcription profiles of MDR1 overexpressing, clinical C. albicans isolates and matched, drug-susceptible isolates from the same patients, we identified a transcription factor, termed multidrug resistance regulator 1 (MRR1), which was upregulated in all resistant isolates and turned out to be a central regulator of MDR1 expression. Resistant isolates contained point mutations in MRR1, which rendered the transcription factor constitutively active. Introduction of these mutated alleles into a susceptible strain caused MDR1 overexpression und multidrug resistance. Inactivation of MRR1 in clinical isolates abolished MDR1 expression and affected fluconazole resistance even more strongly than deletion of the MDR1 efflux pump itself, indicating that additional Mrr1p target genes, which were identified by genome-wide gene expression analysis, contribute to fluconazole resistance. These findings provide detailed insights into the molecular basis of multidrug resistance in one of the most important human fungal pathogens.
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Affiliation(s)
- Joachim Morschhäuser
- Institut für Molekulare Infektionsbiologie, Universität Würzburg, Würzburg, Germany.
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48
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Salgado-Parreño FJ, Alcoba-Flórez J, Arias A, Moragues MD, Quindós G, Pontón J, Arévalo MP. In VitroActivities of Voriconazole and Five Licensed Antifungal Agents AgainstCandida dubliniensis:Comparison of CLSI M27-A2, Sensititre YeastOne, Disk Diffusion, and Etest Methods. Microb Drug Resist 2006; 12:246-51. [PMID: 17227209 DOI: 10.1089/mdr.2006.12.246] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
We compared the in vitro activity of six antifungal agents against 62 isolates of Candida dubliniensis by the Clinical Laboratory Standards Institute (CLSI [formerly National Committee for the Clinical Laboratory Standards]) M27-A2, Sensititre YeastOne, disk diffusion, and Etest methods and we studied the effect of the time of reading. For the azoles, voriconazole was the most potent in vitro followed by fluconazole, ketoconazole, and itraconazole. All the isolates were susceptible to amphotericin B and flucytosine. The highest rate of resistance was obtained against itraconazole with a high number of isolates defined as susceptible dose-dependent. At 24 hr, 100% of the isolates were susceptible to ketoconazole, amphotericin B, and flucytosine, 98% susceptible to voriconazole and fluconazole, and 95% for itraconazole. At 48 hr, 100% of the isolates remained susceptible for flucytosine and amphotericin B, 95% for voriconazole, 93% for fluconazole, 90% for ketoconazole, and 82% for itraconazole. The agreement between the CLSI and the other methods was better at 24 than 48 hr.
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Affiliation(s)
- F J Salgado-Parreño
- Departamento de Medicina Preventiva y Salud Pública, Facultad de Medicina, Universidad de La Laguna, Tenerife, Spain
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Hiller D, Sanglard D, Morschhäuser J. Overexpression of the MDR1 gene is sufficient to confer increased resistance to toxic compounds in Candida albicans. Antimicrob Agents Chemother 2006; 50:1365-71. [PMID: 16569853 PMCID: PMC1426927 DOI: 10.1128/aac.50.4.1365-1371.2006] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Overexpression of MDR1, which encodes a membrane transport protein of the major facilitator superfamily, is one mechanism by which the human fungal pathogen Candida albicans can develop increased resistance to the antifungal drug fluconazole and other toxic compounds. In clinical C. albicans isolates, constitutive MDR1 overexpression is accompanied by the upregulation of other genes, but it is not known if these additional alterations are required for Mdr1p function and drug resistance. To investigate whether MDR1 overexpression is sufficient to confer a drug-resistant phenotype in C. albicans, we expressed the MDR1 gene from the strong ADH1 promoter in C. albicans laboratory strains that did not express the endogenous MDR1 gene as well as in a fluconazole-resistant clinical C. albicans isolate in which the endogenous MDR1 alleles had been deleted and in a matched fluconazole-susceptible isolate from the same patient. Forced MDR1 overexpression resulted in increased resistance to the putative Mdr1p substrates cerulenin and brefeldin A, and this resistance did not depend on the additional alterations which occurred during drug resistance development in the clinical isolates. In contrast, artificial expression of the MDR1 gene from the ADH1 promoter did not enhance or only slightly enhanced fluconazole resistance, presumably because Mdr1p expression levels in the transformants were considerably lower than those observed in the fluconazole-resistant clinical isolate. These results demonstrate that MDR1 overexpression in C. albicans is sufficient to confer resistance to some toxic compounds that are substrates of this efflux pump but that the degree of resistance depends on the Mdr1p expression level.
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Affiliation(s)
- Davina Hiller
- Institut für Molekulare Infektionsbiologie, Universität Würzburg, Röntgenring 11, D-97070 Würzburg, Germany, and Institute of Microbiology, University Hospital Lausanne, Switzerland
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50
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Cernicka J, Subik J. Resistance mechanisms in fluconazole-resistant Candida albicans isolates from vaginal candidiasis. Int J Antimicrob Agents 2006; 27:403-8. [PMID: 16621465 DOI: 10.1016/j.ijantimicag.2005.12.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2005] [Accepted: 12/08/2005] [Indexed: 11/18/2022]
Abstract
Candida albicans is the most frequently identified yeast species causing mycotic vaginitis. A significant number of vaginal yeast isolates are resistant to azole antifungal agents in vitro. Here we investigated the molecular mechanisms of resistance in 22 randomly selected fluconazole-resistant vaginal C. albicans isolates. Twelve isolates in this collection were found to be cross-resistant to itraconazole and 15 to voriconazole. Most of them also displayed decreased susceptibility to terbinafine. Northern blot analyses revealed overexpression of the MDR1 gene in all isolates, which in some isolates was accompanied by elevated levels of CDR1/CDR2 and ERG11 expression. Sequence analysis of the polymerase chain reaction-amplified ERG11 gene of selected azole-resistant isolates identified D116E and V488I amino acid alterations in Erg11p that are known to be conserved in fluconazole-resistant strains. The results demonstrate that decreased susceptibilities of vaginal yeast isolates to clinically used azole derivatives are the result of a combination of several molecular mechanisms involving drug efflux and alterations in the structure or cellular amount of 14-alpha-lanosterol demethylase.
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Affiliation(s)
- Jana Cernicka
- Comenius University in Bratislava, Faculty of Natural Sciences, Department of Microbiology and Virology, Mlynska dolina B-2, 842 15 Bratislava 4, Slovak Republic
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