151
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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: 260] [Impact Index Per Article: 20.0] [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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152
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Kumar R, Chadha S, Saraswat D, Bajwa JS, Li RA, Conti HR, Edgerton M. Histatin 5 uptake by Candida albicans utilizes polyamine transporters Dur3 and Dur31 proteins. J Biol Chem 2011; 286:43748-43758. [PMID: 22033918 DOI: 10.1074/jbc.m111.311175] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Histatin 5 (Hst 5) is a salivary gland-secreted cationic peptide with potent fungicidal activity against Candida albicans. Hst 5 kills fungal cells following intracellular translocation, although its selective transport mechanism is unknown. C. albicans cells grown in the presence of polyamines were resistant to Hst 5 due to reduced intracellular uptake, suggesting that this cationic peptide may enter candidal cells through native yeast polyamine transporters. Based upon homology to known Saccharomyces cerevisiae polyamine permeases, we identified six C. albicans Dur polyamine transporter family members and propose a new nomenclature. Gene deletion mutants were constructed for C. albicans polyamine transporters Dur3, Dur31, Dur33, Dur34, and were tested for Hst 5 sensitivity and uptake of spermidine. We found spermidine uptake and Hst 5 mediated killing were decreased significantly in Δdur3, Δdur31, and Δdur3/Δdur31 strains; whereas a DUR3 overexpression strain increased Hst 5 sensitivity and higher spermidine uptake. Treatment of cells with a spermidine synthase inhibitor increased spermidine uptake and Hst 5 killing, whereas protonophores and cold treatment reduced spermidine uptake. Inhibition assays showed that Hst 5 is a competitive analog of spermidine for uptake into C. albicans cells, and that Hst 5 Ki values were increased by 80-fold in Δdur3/Δdur31 cells. Thus, Dur3p and Dur31p are preferential spermidine transporters used by Hst 5 for its entry into candidal cells. Understanding of polyamine transporter-mediated internalization of Hst 5 provides new insights into the uptake mechanism for C. albicans toxicity, and further suggests design for targeted fungal therapeutic agents.
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Affiliation(s)
- Rohitashw Kumar
- Department of Oral Biology, School of Dental Medicine, University at Buffalo, Buffalo, New York 14214
| | - Sonia Chadha
- Department of Oral Biology, School of Dental Medicine, University at Buffalo, Buffalo, New York 14214; Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Mumbai 400085, India
| | - Darpan Saraswat
- Department of Oral Biology, School of Dental Medicine, University at Buffalo, Buffalo, New York 14214
| | - Jashanjot Singh Bajwa
- Department of Oral Biology, School of Dental Medicine, University at Buffalo, Buffalo, New York 14214
| | - Rui A Li
- Department of Oral Biology, School of Dental Medicine, University at Buffalo, Buffalo, New York 14214
| | - Heather R Conti
- Department of Oral Biology, School of Dental Medicine, University at Buffalo, Buffalo, New York 14214
| | - Mira Edgerton
- Department of Oral Biology, School of Dental Medicine, University at Buffalo, Buffalo, New York 14214.
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153
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Paulsen JL, Bendel SD, Anderson AC. Crystal structures of Candida albicans dihydrofolate reductase bound to propargyl-linked antifolates reveal the flexibility of active site loop residues critical for ligand potency and selectivity. Chem Biol Drug Des 2011; 78:505-12. [PMID: 21726415 PMCID: PMC3171590 DOI: 10.1111/j.1747-0285.2011.01169.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Candida albicans and Candida glabrata cause fungal bloodstream infections that are associated with significant mortality. As part of an effort to develop potent and selective antifolates that target dihydrofolate reductase (DHFR) from Candida species, we report three ternary crystal structures of C. albicans DHFR (CaDHFR) bound to novel propargyl-linked analogs. Consistent with earlier modeling results, these structures show that hydrophobic pockets in the binding site may be exploited to increase ligand potency. The crystal structures also confirm that loop residues Thr 58- Phe 66, which flank the active site and influence ligand potency and selectivity, adopt multiple conformations. To aid the development of a dual Candida spp. inhibitor, three new crystal structures of C. glabrata DHFR (CgDHFR) bound to similar ligands as those bound in the ternary structures of CaDHFR are also reported here. Loop residues 58-66 in CgDHFR and human DHFR are 1 and 3 Å closer to the folate binding site, respectively, than loop residues in CaDHFR, suggesting that a properly size ligand could be a potent and selective dual inhibitor of CaDHFR and CgDHFR.
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Affiliation(s)
| | | | - Amy C. Anderson
- Corresponding author: Amy C. Anderson, Dept. of Pharmaceutical Sciences, University of Connecticut, 69 N. Eagleville Rd., Storrs, CT 06269, , phone: (860)486-6145, fax: (860)486-6857
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154
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Borah S, Shivarathri R, Kaur R. The Rho1 GTPase-activating protein CgBem2 is required for survival of azole stress in Candida glabrata. J Biol Chem 2011; 286:34311-24. [PMID: 21832071 PMCID: PMC3190821 DOI: 10.1074/jbc.m111.264671] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Revised: 07/19/2011] [Indexed: 12/13/2022] Open
Abstract
Invasive fungal infections are common clinical complications of neonates, critically ill, and immunocompromised patients worldwide. Candida species are the leading cause of disseminated fungal infections, with Candida albicans being the most prevalent species. Candida glabrata, the second/third most common cause of candidemia, shows reduced susceptibility to a widely used antifungal drug fluconazole. Here, we present findings from a screen of 9134 C. glabrata Tn7 insertion mutants for altered survival profiles in the presence of fluconazole. We have identified two components of RNA polymerase II mediator complex, three players of Rho GTPase-mediated signaling cascade, and two proteins implicated in actin cytoskeleton biogenesis and ergosterol biosynthesis that are required to sustain viability during fluconazole stress. We show that exposure to fluconazole leads to activation of the protein kinase C (PKC)-mediated cell wall integrity pathway in C. glabrata. Our data demonstrate that disruption of a RhoGAP (GTPase activating protein) domain-containing protein, CgBem2, results in bud-emergence defects, azole susceptibility, and constitutive activation of CgRho1-regulated CgPkc1 signaling cascade and cell wall-related phenotypes. The viability loss of Cgbem2Δ mutant upon fluconazole treatment could be partially rescued by the PKC inhibitor staurosporine. Additionally, we present evidence that CgBEM2 is required for the transcriptional activation of genes encoding multidrug efflux pumps in response to fluconazole exposure. Last, we report that Hsp90 inhibitor geldanamycin renders fluconazole a fungicidal drug in C. glabrata.
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Affiliation(s)
- Sapan Borah
- From the Centre for DNA Fingerprinting and Diagnostics, Building 7, Gruhakalpa, 5-4-399/B, Nampally, Hyderabad 500001, India
| | - Raju Shivarathri
- From the Centre for DNA Fingerprinting and Diagnostics, Building 7, Gruhakalpa, 5-4-399/B, Nampally, Hyderabad 500001, India
| | - Rupinder Kaur
- From the Centre for DNA Fingerprinting and Diagnostics, Building 7, Gruhakalpa, 5-4-399/B, Nampally, Hyderabad 500001, India
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155
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Tanabe K, Lamping E, Nagi M, Okawada A, Holmes AR, Miyazaki Y, Cannon RD, Monk BC, Niimi M. Chimeras of Candida albicans Cdr1p and Cdr2p reveal features of pleiotropic drug resistance transporter structure and function. Mol Microbiol 2011; 82:416-33. [PMID: 21895791 DOI: 10.1111/j.1365-2958.2011.07820.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Members of the pleiotropic drug resistance (PDR) family of ATP binding cassette (ABC) transporters consist of two homologous halves, each containing a nucleotide binding domain (NBD) and a transmembrane domain (TMD). The PDR transporters efflux a variety of hydrophobic xenobiotics and despite the frequent association of their overexpression with the multidrug resistance of fungal pathogens, the transport mechanism of these transporters is poorly understood. Twenty-eight chimeric constructs between Candida albicans Cdr1p (CaCdr1p) and Cdr2p (CaCdr2p), two closely related but functionally distinguishable PDR transporters, were expressed in Saccharomyces cerevisiae. All chimeras expressed equally well, localized properly at the plasma membrane, retained their transport ability, but their substrate and inhibitor specificities differed significantly between individual constructs. A detailed characterization of these proteins revealed structural features that contribute to their substrate specificities and their transport mechanism. It appears that most transmembrane spans of CaCdr1p and CaCdr2p provide or affect multiple, probably overlapping, substrate and inhibitor binding site(s) similar to mammalian ABC transporters. The NBDs, in particular NBD1 and/or the ∼150 amino acids N-terminal to NBD1, can also modulate the substrate specificities of CaCdr1p and CaCdr2p.
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Affiliation(s)
- Koichi Tanabe
- Department of Bioactive Molecules, National Institute of Infectious Diseases, Tokyo 162-8640, Japan
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156
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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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157
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Prates RA, Kato IT, Ribeiro MS, Tegos GP, Hamblin MR. Influence of multidrug efflux systems on methylene blue-mediated photodynamic inactivation of Candida albicans. J Antimicrob Chemother 2011; 66:1525-32. [PMID: 21525022 DOI: 10.1093/jac/dkr160] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
OBJECTIVES To investigate whether the major fungal multidrug efflux systems (MESs) affect the efficiency of methylene blue (MB)-mediated antimicrobial photodynamic inactivation (APDI) in pathogenic fungi and test specific inhibitors of these efflux systems to potentiate APDI. METHODS Candida albicans wild-type and mutants that overexpressed two classes of MESs [ATP-binding cassette (ABC) and major facilitator superfamily (MFS)] were tested for APDI using MB as the photosensitizer with and without addition of MES inhibitors. The uptake and cytoplasm localization of photosensitizer were achieved using laser confocal microscopy. RESULTS ABC MES overexpression reduced MB accumulation and APDI killing more than MFS MES overexpression. Furthermore, by combining MB APDI with the ABC inhibitor verapamil, fungal killing and MB uptake were potentiated, while by combining MB APDI with the MFS inhibitor INF(271), fungal killing and MB uptake were inhibited. This latter surprising finding may be explained by the hypothesis that the MFS channel can also serve as an uptake mechanism for MB. CONCLUSIONS The ABC pumps are directly implicated in MB efflux from the cell cytoplasm. Both the influx and efflux of MB may be regulated by MFS systems, and blocking this gate before incubation with MB can decrease the uptake and APDI effects. An ABC inhibitor could be usefully combined with MB APDI for treating C. albicans infections.
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Affiliation(s)
- Renato A Prates
- Center for Lasers and Applications, IPEN-CNEN/SP, São Paulo, SP 05508-000, Brazil
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158
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Oxidative stress response and virulence factors in Candida glabrata clinical isolates. Folia Microbiol (Praha) 2011; 56:116-21. [PMID: 21416384 DOI: 10.1007/s12223-011-0016-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2010] [Accepted: 01/17/2011] [Indexed: 01/19/2023]
Abstract
We determined the susceptibility to oxidative stress and assessed the four virulence factors of the 38 Candida glabrata clinical isolates originating from two teaching hospitals in Slovakia. All the isolates were susceptible to hydrogen peroxide, diamide, and 7-chlorotetrazolo[5,1-c]benzo[1,2,4]triazine (CTBT) inducing an increased formation of reactive oxygen species in fungal cells. The mean relative cell surface hydrophobicity (CSH) of isolates was 21.9, ranging from 1.92 to 56.96. All isolates showed biofilm formation. A high biofilm formation was observed among 60.5% of isolates. Positive correlations were observed between biofilm formation and moderate values of CSHs. The 76.3% and 84.2% of isolates displayed varying degrees of proteinase and phospholipase activity, respectively. These results demonstrate a differential distribution of factors contributing to virulence of C. glabrata clinical isolates and point to their significance in pathogenesis that would be targeted by novel antifungals.
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159
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Ferrari S, Sanguinetti M, Torelli R, Posteraro B, Sanglard D. Contribution of CgPDR1-regulated genes in enhanced virulence of azole-resistant Candida glabrata. PLoS One 2011; 6:e17589. [PMID: 21408004 PMCID: PMC3052359 DOI: 10.1371/journal.pone.0017589] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Accepted: 01/27/2011] [Indexed: 12/20/2022] Open
Abstract
In Candida glabrata, the transcription factor CgPdr1 is involved
in resistance to azole antifungals via upregulation of ATP binding cassette
(ABC)-transporter genes including at least CgCDR1,
CgCDR2 and CgSNQ2. A high diversity of GOF
(gain-of-function) mutations in CgPDR1 exists for the
upregulation of ABC-transporters. These mutations enhance C.
glabrata virulence in animal models, thus indicating that
CgPDR1 might regulate the expression of yet unidentified
virulence factors. We hypothesized that CgPdr1-dependent virulence factor(s)
should be commonly regulated by all GOF mutations in CgPDR1. As
deduced from transcript profiling with microarrays, a high number of genes (up
to 385) were differentially regulated by a selected number (7) of GOF mutations
expressed in the same genetic background. Surprisingly, the transcriptional
profiles resulting from expression of GOF mutations showed minimal overlap in
co-regulated genes. Only two genes, CgCDR1 and
PUP1 (for PDR1upregulated and encoding a mitochondrial protein), were
commonly upregulated by all tested GOFs. While both genes mediated azole
resistance, although to different extents, their deletions in an azole-resistant
isolate led to a reduction of virulence and decreased tissue burden as compared
to clinical parents. As expected from their role in C. glabrata
virulence, the two genes were expressed as well in vitro and
in vivo. The individual overexpression of these two genes
in a CgPDR1-independent manner could partially restore
phenotypes obtained in clinical isolates. These data therefore demonstrate that
at least these two CgPDR1-dependent and -upregulated genes
contribute to the enhanced virulence of C. glabrata that
acquired azole resistance.
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Affiliation(s)
- Sélène Ferrari
- Institute of Microbiology, University of
Lausanne and University Hospital Center, Lausanne, Switzerland
| | | | - Riccardo Torelli
- Institute of Microbiology, Università
Cattolica del Sacro Cuore, Rome, Italy
| | - Brunella Posteraro
- Institute of Microbiology, Università
Cattolica del Sacro Cuore, Rome, Italy
| | - Dominique Sanglard
- Institute of Microbiology, University of
Lausanne and University Hospital Center, Lausanne, Switzerland
- * E-mail:
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160
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Microbiological screening of Irish patients with autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy reveals persistence of Candida albicans strains, gradual reduction in susceptibility to azoles, and incidences of clinical signs of oral candidiasis without culture evidence. J Clin Microbiol 2011; 49:1879-89. [PMID: 21367996 DOI: 10.1128/jcm.00026-11] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Patients with autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) are prone to chronic mucocutaneous candidiasis, which is often treated with azoles. The purpose of this study was to characterize the oral Candida populations from 16 Irish APECED patients, who comprise approximately half the total number identified in Ireland, and to examine the effect of intermittent antifungal therapy on the azole susceptibility patterns of Candida isolates. Patients attended between one and four clinical evaluations over a 5-year period, providing oral rinses and/or oral swab samples each time. Candida was recovered from 14/16 patients, and Candida albicans was the only Candida species identified. Interestingly, clinical diagnosis of candidiasis did not correlate with microbiological evidence of Candida infection at 7/22 (32%) clinical assessments. Multilocus sequence typing analysis of C. albicans isolates recovered from the same patients on separate occasions identified the same sequence type each time. Fluconazole resistance was detected in isolates from one patient, and isolates exhibiting a progressive reduction in itraconazole and/or fluconazole susceptibility were identified in a further 3/16 patients, in each case correlating with the upregulation of CDR- and MDR-encoded efflux pumps. Mutations were also identified in the ERG11 and the TAC1 genes of isolates from these four patients; some of these mutations have previously been associated with azole resistance. The findings suggest that alternative Candida treatment options, other than azoles such as chlorhexidine, should be considered in APECED patients and that clinical diagnosis of oral candidiasis should be confirmed by culture prior to the commencement of anti-Candida therapy.
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161
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Loss of mitochondrial functions associated with azole resistance in Candida glabrata results in enhanced virulence in mice. Antimicrob Agents Chemother 2011; 55:1852-60. [PMID: 21321146 DOI: 10.1128/aac.01271-10] [Citation(s) in RCA: 108] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Mitochondrial dysfunction is one of the possible mechanisms by which azole resistance can occur in Candida glabrata. Cells with mitochondrial DNA deficiency (so-called "petite mutants") upregulate ATP binding cassette (ABC) transporter genes and thus display increased resistance to azoles. Isolation of such C. glabrata mutants from patients receiving antifungal therapy or prophylaxis has been rarely reported. In this study, we characterized two sequential and related C. glabrata isolates recovered from the same patient undergoing azole therapy. The first isolate (BPY40) was azole susceptible (fluconazole MIC, 4 μg/ml), and the second (BPY41) was azole resistant (fluconazole MIC, >256 μg/ml). BPY41 exhibited mitochondrial dysfunction and upregulation of the ABC transporter genes C. glabrata CDR1 (CgCDR1), CgCDR2, and CgSNQ2. We next assessed whether mitochondrial dysfunction conferred a selective advantage during host infection by testing the virulence of BPY40 and BPY41 in mice. Surprisingly, even with in vitro growth deficiency compared to BPY40, BPY41 was more virulent (as judged by mortality and fungal tissue burden) than BPY40 in both systemic and vaginal murine infection models. The increased virulence of the petite mutant correlated with a drastic gain of fitness in mice compared to that of its parental isolate. To understand this unexpected feature, genome-wide changes in gene expression driven by the petite mutation were analyzed by use of microarrays during in vitro growth. Enrichment of specific biological processes (oxido-reductive metabolism and the stress response) was observed in BPY41, all of which was consistent with mitochondrial dysfunction. Finally, some genes involved in cell wall remodelling were upregulated in BPY41 compared to BPY40, which may partially explain the enhanced virulence of BPY41. In conclusion, this study shows for the first time that mitochondrial dysfunction selected in vivo under azole therapy, even if strongly affecting in vitro growth characteristics, can confer a selective advantage under host conditions, allowing the C. glabrata mutant to be more virulent than wild-type isolates.
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162
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Tscherner M, Schwarzmüller T, Kuchler K. Pathogenesis and Antifungal Drug Resistance of the Human Fungal Pathogen Candida glabrata. Pharmaceuticals (Basel) 2011. [PMCID: PMC4052548 DOI: 10.3390/ph4010169] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Candida glabrata is a major opportunistic human fungal pathogen causing superficial as well as systemic infections in immunocompromised individuals and several other patient cohorts. C. glabrata represents the second most prevalent cause of candidemia and a better understanding of its virulence and drug resistance mechanisms is thus of high medical relevance. In contrast to the diploid dimorphic pathogen C. albicans, whose ability to undergo filamentation is considered a major virulence trait, C. glabrata has a haploid genome and lacks the ability to switch to filamentous growth. A major impediment for the clinical therapy of C. glabrata infections is its high intrinsic resistance to several antifungal drugs, especially azoles. Further, the development of antifungal resistance, particularly during prolonged and prophylactic therapies is diminishing efficacies of therapeutic interventions. In addition, C. glabrata harbors a large repertoire of adhesins involved in the adherence to host epithelia. Interestingly, genome plasticity, phenotypic switching or the remarkable ability to persist and survive inside host immune cells further contribute to the pathogenicity of C. glabrata. In this comprehensive review, we want to emphasize and discuss the mechanisms underlying virulence and drug resistance of C. glabrata, and discuss its ability to escape from the host immune surveillance or persist inside host cells.
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Affiliation(s)
| | | | - Karl Kuchler
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +43-1-4277-61807; Fax: +43-1-4277-9618
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163
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Overcoming the heterologous bias: An in vivo functional analysis of multidrug efflux transporter, CgCdr1p in matched pair clinical isolates of Candida glabrata. Biochem Biophys Res Commun 2011; 404:357-63. [DOI: 10.1016/j.bbrc.2010.11.123] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Accepted: 11/27/2010] [Indexed: 11/20/2022]
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164
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Genomewide expression profile analysis of the Candida glabrata Pdr1 regulon. EUKARYOTIC CELL 2010; 10:373-83. [PMID: 21193550 DOI: 10.1128/ec.00073-10] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The ABC transporters Candida glabrata Cdr1 (CgCdr1), CgPdh1, and CgSnq2 are known to mediate azole resistance in the pathogenic fungus C. glabrata. Activating mutations in CgPDR1, a zinc cluster transcription factor, result in constitutive upregulation of these ABC transporter genes but to various degrees. We examined the genomewide gene expression profiles of two matched azole-susceptible and -resistant C. glabrata clinical isolate pairs. Of the differentially expressed genes identified in the gene expression profiles for these two matched pairs, there were 28 genes commonly upregulated with CgCDR1 in both isolate sets including YOR1, LCB5, RTA1, POG1, HFD1, and several members of the FLO gene family of flocculation genes. We then sequenced CgPDR1 from each susceptible and resistant isolate and found two novel activating mutations that conferred increased resistance when they were expressed in a common background strain in which CgPDR1 had been disrupted. Microarray analysis comparing these reengineered strains to their respective parent strains identified a set of commonly differentially expressed genes, including CgCDR1, YOR1, and YIM1, as well as genes uniquely regulated by specific mutations. Our results demonstrate that while CgPdr1 activates a broad repertoire of genes, specific activating mutations result in the activation of discrete subsets of this repertoire.
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165
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Goffa E, Bialkova A, Batova M, Dzugasova V, Subik J. A yeast cell-based system for screening Candida glabrata multidrug resistance reversal agents and selection of loss-of-function pdr1 mutants. FEMS Yeast Res 2010; 11:155-9. [PMID: 21129149 DOI: 10.1111/j.1567-1364.2010.00702.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
In the pathogenic yeast Candida glabrata, multidrug resistance is associated with the overexpression of drug efflux pumps caused by gain-of-function mutations in the CgPDR1 gene. CgPdr1p transcription factor, which activates the expression of several drug efflux transporter genes, is considered to be a promising target for compounds sensitizing the multidrug-resistant yeast cells. Here, we describe a cell-based screening system for detecting the inhibitory activity of compounds interfering with the CgPdr1p function in a heterologous genetic background of the hypersensitive Saccharomyces cerevisiae mutant strain. The screening is based on the ability to abrogate the growth defect of cells suffering from the galactose-induced and CgPdr1p-driven overexpression of a dominant lethal pma1(D378N) allele placed under the control of the ScPDR5 promoter. The system allows rapid identification of multidrug resistance reversal agents inhibiting the CgPdr1p activity or loss-of-function Cgpdr1 mutations, and is amenable to high-throughput screening on solid or liquid media.
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Affiliation(s)
- Eduard Goffa
- Department of Microbiology and Virology, Faculty of Natural Sciences, Comenius University in Bratislava, Bratislava, Slovak Republic
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166
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Regulation of the CgPdr1 transcription factor from the pathogen Candida glabrata. EUKARYOTIC CELL 2010; 10:187-97. [PMID: 21131438 DOI: 10.1128/ec.00277-10] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Candida glabrata is an opportunistic human pathogen that is increasingly associated with candidemia, owing in part to the intrinsic and acquired high tolerance the organism exhibits for the important clinical antifungal drug fluconazole. This elevated fluconazole resistance often develops through gain-of-function mutations in the zinc cluster-containing transcriptional regulator C. glabrata Pdr1 (CgPdr1). CgPdr1 induces the expression of an ATP-binding cassette (ABC) transporter-encoding gene, CgCDR1. Saccharomyces cerevisiae has two CgPdr1 homologues called ScPdr1 and ScPdr3. These factors control the expression of an ABC transporter-encoding gene called ScPDR5, which encodes a homologue of CgCDR1. Loss of the mitochondrial genome (ρ(0) cell) or overexpression of the mitochondrial enzyme ScPsd1 induces ScPDR5 expression in a strictly ScPdr3-dependent fashion. ScPdr3 requires the presence of a transcriptional Mediator subunit called Gal11 (Med15) to fully induce ScPDR5 transcription in response to ρ(0) signaling. ScPdr1 does not respond to either ρ(0) signals or ScPsd1 overproduction. In this study, we employed transcriptional fusions between CgPdr1 target promoters, like CgCDR1, to demonstrate that CgPdr1 stimulates gene expression via binding to elements called pleiotropic drug response elements (PDREs). Deletion mapping and electrophoretic mobility shift assays demonstrated that a single PDRE in the CgCDR1 promoter was capable of supporting ρ(0)-induced gene expression. Removal of one of the two ScGal11 homologues from C. glabrata caused a major defect in drug-induced expression of CgCDR1 but had a quantitatively minor effect on ρ(0)-stimulated transcription. These data demonstrate that CgPdr1 appears to combine features of ScPdr1 and ScPdr3 to produce a transcription factor with chimeric regulatory properties.
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167
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Wild-type MIC distributions, epidemiological cutoff values and species-specific clinical breakpoints for fluconazole and Candida: Time for harmonization of CLSI and EUCAST broth microdilution methods. Drug Resist Updat 2010; 13:180-95. [PMID: 21050800 DOI: 10.1016/j.drup.2010.09.002] [Citation(s) in RCA: 225] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2010] [Revised: 09/21/2010] [Accepted: 09/22/2010] [Indexed: 11/22/2022]
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168
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169
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Loureiro Y Penha CV, Kubitschek PHB, Larcher G, Perales J, Rodriguez León I, Lopes-Bezerra LM, Bouchara JP. Proteomic analysis of cytosolic proteins associated with petite mutations in Candida glabrata. Braz J Med Biol Res 2010; 43:1203-14. [PMID: 21085892 DOI: 10.1590/s0100-879x2010007500125] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Accepted: 10/21/2010] [Indexed: 11/22/2022] Open
Abstract
The incidence of superficial or deep-seated infections due to Candida glabrata has increased markedly, probably because of the low intrinsic susceptibility of this microorganism to azole antifungals and its relatively high propensity to acquire azole resistance. To determine changes in the C. glabrata proteome associated with petite mutations, cytosolic extracts from an azole-resistant petite mutant of C. glabrata induced by exposure to ethidium bromide, and from its azole-susceptible parent isolate were compared by two-dimensional polyacrylamide gel electrophoresis. Proteins of interest were identified by peptide mass fingerprinting or sequence tagging using a matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometer. Tryptic peptides from a total of 160 Coomassie-positive spots were analyzed for each strain. Sixty-five different proteins were identified in the cytosolic extracts of the parent strain and 58 in the petite mutant. Among the proteins identified, 10 were higher in the mutant strain, whereas 23 were lower compared to the parent strain. The results revealed a significant decrease in the enzymes associated with the metabolic rate of mutant cells such as aconitase, transaldolase, and pyruvate kinase, and changes in the levels of specific heat shock proteins. Moreover, transketolase, aconitase and catalase activity measurements decreased significantly in the ethidium bromide-induced petite mutant. These data may be useful for designing experiments to obtain a better understanding of the nuclear response to impairment of mitochondrial function associated with this mutation in C. glabrata.
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Affiliation(s)
- C V Loureiro Y Penha
- Instituto de Biologia Roberto Alcântara Gomes, Universidade do Estado do Rio de Janeiro, RJ, Brasil.
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170
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Siikala E, Rautemaa R, Richardson M, Saxen H, Bowyer P, Sanglard D. Persistent Candida albicans colonization and molecular mechanisms of azole resistance in autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) patients. J Antimicrob Chemother 2010; 65:2505-13. [PMID: 20876623 DOI: 10.1093/jac/dkq354] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
OBJECTIVES Patients with autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED, APS-I) suffer from chronic candidosis caused mainly by Candida albicans, and repeated courses of azole antifungals have led to the development of resistance in the APECED patient population in Finland. The aim of our study was to address whether the patients are persistently colonized with the same or genetically closely related strains, whether epidemic strains are present and which molecular mechanisms account for azole resistance. METHODS Sets of C. albicans (n = 19) isolates from nine APECED patients reported with decreased susceptibility to fluconazole isolated up to 9 years apart were included. The strains were typed by multilocus sequence typing. CDR1/2, MDR1 and ERG11 mRNA expression was analysed by northern blotting and Cdr1, Cdr2 and Mdr1 protein expression by western blotting, and TAC1 and ERG11 genes were sequenced. RESULTS All seven patients with multiple C. albicans isolates analysed were persistently colonized with the same or a genetically closely related strain for a mean of 5 years. All patients were colonized with different strains and no epidemic strains were found. The major molecular mechanisms behind the azole resistance were mutations in TAC1 contributing to overexpression of CDR1 and CDR2. Six new TAC1 mutations were found, one of which (N740S) is likely to be a gain-of-function mutation. Most isolates were found to have gained multiple TAC1 and ERG11 point mutations. CONCLUSIONS Despite clinically successful treatment leading to relief of symptoms, colonization by C. albicans strains is persistent within APECED patients. Microevolution and point mutations occur within strains, leading to the development of azole-resistant isolates.
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Affiliation(s)
- Emilia Siikala
- Department of Bacteriology and Immunology, Haartman Institute, University of Helsinki, Helsinki, Finland.
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171
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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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172
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Novel acid phosphatase in Candida glabrata suggests selective pressure and niche specialization in the phosphate signal transduction pathway. Genetics 2010; 186:885-95. [PMID: 20739710 DOI: 10.1534/genetics.110.120824] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Evolution through natural selection suggests unnecessary genes are lost. We observed that the yeast Candida glabrata lost the gene encoding a phosphate-repressible acid phosphatase (PHO5) present in many yeasts including Saccharomyces cerevisiae. However, C. glabrata still had phosphate starvation-inducible phosphatase activity. Screening a C. glabrata genomic library, we identified CgPMU2, a member of a three-gene family that contains a phosphomutase-like domain. This small-scale gene duplication event could allow for sub- or neofunctionalization. On the basis of phylogenetic and biochemical characterizations, CgPMU2 has neofunctionalized to become a broad range, phosphate starvation-regulated acid phosphatase, which functionally replaces PHO5 in this pathogenic yeast. We determined that CgPmu2, unlike ScPho5, is not able to hydrolyze phytic acid (inositol hexakisphosphate). Phytic acid is present in fruits and seeds where S. cerevisiae grows, but is not abundant in mammalian tissues where C. glabrata grows. We demonstrated that C. glabrata is limited from an environment where phytic acid is the only source of phosphate. Our work suggests that during evolutionary time, the selection for the ancestral PHO5 was lost and that C. glabrata neofunctionalized a weak phosphatase to replace PHO5. Convergent evolution of a phosphate starvation-inducible acid phosphatase in C. glabrata relative to most yeast species provides an example of how small changes in signal transduction pathways can mediate genetic isolation and uncovers a potential speciation gene.
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173
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Tsai HF, Sammons LR, Zhang X, Suffis SD, Su Q, Myers TG, Marr KA, Bennett JE. Microarray and molecular analyses of the azole resistance mechanism in Candida glabrata oropharyngeal isolates. Antimicrob Agents Chemother 2010; 54:3308-17. [PMID: 20547810 PMCID: PMC2916311 DOI: 10.1128/aac.00535-10] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2010] [Revised: 05/15/2010] [Accepted: 05/30/2010] [Indexed: 12/24/2022] Open
Abstract
DNA microarrays were used to analyze Candida glabrata oropharyngeal isolates from seven hematopoietic stem cell transplant recipients whose isolates developed azole resistance while the recipients received fluconazole prophylaxis. Transcriptional profiling of the paired isolates revealed 19 genes upregulated in the majority of resistant isolates compared to their paired susceptible isolates. All seven resistant isolates had greater than 2-fold upregulation of C. glabrata PDR1 (CgPDR1), a master transcriptional regulator of the pleiotropic drug resistance (PDR) network, and all seven resistant isolates showed upregulation of known CgPDR1 target genes. The altered transcriptome can be explained in part by the observation that all seven resistant isolates had acquired a single nonsynonymous mutation in their CgPDR1 open reading frame. Four mutations occurred in the regulatory domain (L280P, L344S, G348A, and S391L) and one in the activation domain (G943S), while two mutations (N764I and R772I) occurred in an undefined region. Association of azole resistance and the CgPDR1 mutations was investigated in the same genetic background by introducing the CgPDR1 sequences from one sensitive isolate and five resistant isolates into a laboratory azole-hypersusceptible strain (Cgpdr1 strain) via integrative transformation. The Cgpdr1 strain was restored to wild-type fluconazole susceptibility when transformed with CgPDR1 from the susceptible isolate but became resistant when transformed with CgPDR1 from the resistant isolates. However, despite the identical genetic backgrounds, upregulation of CgPDR1 and CgPDR1 target genes varied between the five transformants, independent of the domain locations in which the mutations occurred. In summary, gain-of-function mutations in CgPDR1 contributed to the clinical azole resistance, but different mutations had various degrees of impact on the CgPDR1 target genes.
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Affiliation(s)
- Huei-Fung Tsai
- Clinical Mycology Section, Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, Genomic Technologies Section, Research Technologies Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Lindsay R. Sammons
- Clinical Mycology Section, Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, Genomic Technologies Section, Research Technologies Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Xiaozhen Zhang
- Clinical Mycology Section, Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, Genomic Technologies Section, Research Technologies Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Sara D. Suffis
- Clinical Mycology Section, Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, Genomic Technologies Section, Research Technologies Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Qin Su
- Clinical Mycology Section, Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, Genomic Technologies Section, Research Technologies Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Timothy G. Myers
- Clinical Mycology Section, Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, Genomic Technologies Section, Research Technologies Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Kieren A. Marr
- Clinical Mycology Section, Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, Genomic Technologies Section, Research Technologies Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - John E. Bennett
- Clinical Mycology Section, Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, Genomic Technologies Section, Research Technologies Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
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174
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Kuo D, Tan K, Zinman G, Ravasi T, Bar-Joseph Z, Ideker T. Evolutionary divergence in the fungal response to fluconazole revealed by soft clustering. Genome Biol 2010; 11:R77. [PMID: 20653936 PMCID: PMC2926788 DOI: 10.1186/gb-2010-11-7-r77] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Revised: 07/09/2010] [Accepted: 07/23/2010] [Indexed: 11/25/2022] Open
Abstract
Background Fungal infections are an emerging health risk, especially those involving yeast that are resistant to antifungal agents. To understand the range of mechanisms by which yeasts can respond to anti-fungals, we compared gene expression patterns across three evolutionarily distant species - Saccharomyces cerevisiae, Candida glabrata and Kluyveromyces lactis - over time following fluconazole exposure. Results Conserved and diverged expression patterns were identified using a novel soft clustering algorithm that concurrently clusters data from all species while incorporating sequence orthology. The analysis suggests complementary strategies for coping with ergosterol depletion by azoles - Saccharomyces imports exogenous ergosterol, Candida exports fluconazole, while Kluyveromyces does neither, leading to extreme sensitivity. In support of this hypothesis we find that only Saccharomyces becomes more azole resistant in ergosterol-supplemented media; that this depends on sterol importers Aus1 and Pdr11; and that transgenic expression of sterol importers in Kluyveromyces alleviates its drug sensitivity. Conclusions We have compared the dynamic transcriptional responses of three diverse yeast species to fluconazole treatment using a novel clustering algorithm. This approach revealed significant divergence among regulatory programs associated with fluconazole sensitivity. In future, such approaches might be used to survey a wider range of species, drug concentrations and stimuli to reveal conserved and divergent molecular response pathways.
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Affiliation(s)
- Dwight Kuo
- Department of Bioengineering, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
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175
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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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176
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Niimi M, Firth NA, Cannon RD. Antifungal drug resistance of oral fungi. Odontology 2010; 98:15-25. [PMID: 20155503 DOI: 10.1007/s10266-009-0118-3] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2009] [Accepted: 11/28/2009] [Indexed: 01/19/2023]
Abstract
Fungi comprise a minor component of the oral microbiota but give rise to oral disease in a significant proportion of the population. The most common form of oral fungal disease is oral candidiasis, which has a number of presentations. The mainstay for the treatment of oral candidiasis is the use of polyenes, such as nystatin and amphotericin B, and azoles including miconazole, fluconazole, and itraconazole. Resistance of fungi to polyenes is rare, but some Candida species, such as Candida glabrata and C. krusei, are innately less susceptible to azoles, and C. albicans can acquire azole resistance. The main mechanism of high-level fungal azole resistance, measured in vitro, is energy-dependent drug efflux. Most fungi in the oral cavity, however, are present in multispecies biofilms that typically demonstrate an antifungal resistance phenotype. This resistance is the result of multiple factors including the expression of efflux pumps in the fungal cell membrane, biofilm matrix permeability, and a stress response in the fungal cell. Removal of dental biofilms, or treatments to prevent biofilm development in combination with antifungal drugs, may enable better treatment and prevention of oral fungal disease.
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Affiliation(s)
- Masakazu Niimi
- Department of Oral Sciences, School of Dentistry, University of Otago, 310 Great King Street, Dunedin, 9016, New Zealand
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177
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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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178
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Lamping E, Baret PV, Holmes AR, Monk BC, Goffeau A, Cannon RD. Fungal PDR transporters: Phylogeny, topology, motifs and function. Fungal Genet Biol 2010; 47:127-42. [PMID: 19857594 PMCID: PMC2814995 DOI: 10.1016/j.fgb.2009.10.007] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Accepted: 10/15/2009] [Indexed: 10/20/2022]
Abstract
The overexpression of pleiotropic drug resistance (PDR) efflux pumps of the ATP-binding cassette (ABC) transporter superfamily frequently correlates with multidrug resistance. Phylogenetic analysis of 349 full-size ( approximately 160kDa) PDR proteins (Pdrps) from 55 fungal species, including major fungal pathogens, identified nine separate protein clusters (A-G, H1a/H1b and H2). Fungal, plant and human ABCG-family Pdrps possess a nucleotide-binding domain [NBD] and a transmembrane domain [TMD] in a family-defining 'reverse' ABC transporter topology [NBD-TMD] that is duplicated [NBD-TMD](2) in full-size fungal and plant Pdrps. Although full-size Pdrps have similar halves indicating early gene duplication/fusion, they show asymmetry of their NBDs and extracellular loops (ELs). Members of cluster F are most symmetric and may be closely related to the evolutionary ancestor of Pdrps. Unique structural elements are predicted, new PDR-specific motifs identified, and the significance of these and other structural features discussed.
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Affiliation(s)
- Erwin Lamping
- Department of Oral Sciences, University of Otago, Dunedin, New Zealand
| | | | - Ann R. Holmes
- Department of Oral Sciences, University of Otago, Dunedin, New Zealand
| | - Brian C. Monk
- Department of Oral Sciences, University of Otago, Dunedin, New Zealand
| | - Andre Goffeau
- Université catholique de Louvain, Louvain-la-Neuve, Belgium
| | - Richard D. Cannon
- Department of Oral Sciences, University of Otago, Dunedin, New Zealand
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179
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Pfaller MA, Messer SA, Hollis RJ, Boyken L, Tendolkar S, Kroeger J, Diekema DJ. Variation in susceptibility of bloodstream isolates of Candida glabrata to fluconazole according to patient age and geographic location in the United States in 2001 to 2007. J Clin Microbiol 2009; 47:3185-90. [PMID: 19656983 PMCID: PMC2756923 DOI: 10.1128/jcm.00946-09] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Revised: 07/18/2009] [Accepted: 07/29/2009] [Indexed: 11/20/2022] Open
Abstract
We examined the susceptibilities to fluconazole of 642 bloodstream infection (BSI) isolates of Candida glabrata and grouped the isolates by patient age and geographic location within the United States. Susceptibility of C. glabrata to fluconazole was lowest in the northeast region (46%) and was highest in the west (76%). The frequencies of isolation and of fluconazole resistance among C. glabrata BSI isolates were higher in the present study (years 2001 to 2007) than in a previous study conducted from 1992 to 2001. Whereas the frequency of C. glabrata increased with patient age, the rate of fluconazole resistance declined. The oldest age group (> or = 80 years) had the highest proportion of BSI isolates that were C. glabrata (32%) and the lowest rate of fluconazole resistance (5%).
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Affiliation(s)
- M A Pfaller
- Medical Microbiology Division, Department of Pathology, University of Iowa College of Medicine, Iowa City, IA 52242, USA.
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180
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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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181
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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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182
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Reliability of the Vitek 2 yeast susceptibility test for detection of in vitro resistance to fluconazole and voriconazole in clinical isolates of Candida albicans and Candida glabrata. J Clin Microbiol 2009; 47:1927-30. [PMID: 19403774 DOI: 10.1128/jcm.02070-08] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Vitek 2 yeast susceptibility test was evaluated by testing 122 Candida isolates against fluconazole and voriconazole. Excellent categorical agreement with the CLSI broth microdilution method was observed (97.5% for both the azoles). Moreover, the Vitek 2 system was able to identify all but 2 of 59 investigated fluconazole-resistant organisms.
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183
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Cannon RD, Lamping E, Holmes AR, Niimi K, Baret PV, Keniya MV, Tanabe K, Niimi M, Goffeau A, Monk BC. Efflux-mediated antifungal drug resistance. Clin Microbiol Rev 2009; 22:291-321, Table of Contents. [PMID: 19366916 PMCID: PMC2668233 DOI: 10.1128/cmr.00051-08] [Citation(s) in RCA: 385] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Fungi cause serious infections in the immunocompromised and debilitated, and the incidence of invasive mycoses has increased significantly over the last 3 decades. Slow diagnosis and the relatively few classes of antifungal drugs result in high attributable mortality for systemic fungal infections. Azole antifungals are commonly used for fungal infections, but azole resistance can be a problem for some patient groups. High-level, clinically significant azole resistance usually involves overexpression of plasma membrane efflux pumps belonging to the ATP-binding cassette (ABC) or the major facilitator superfamily class of transporters. The heterologous expression of efflux pumps in model systems, such Saccharomyces cerevisiae, has enabled the functional analysis of efflux pumps from a variety of fungi. Phylogenetic analysis of the ABC pleiotropic drug resistance family has provided a new view of the evolution of this important class of efflux pumps. There are several ways in which the clinical significance of efflux-mediated antifungal drug resistance can be mitigated. Alternative antifungal drugs, such as the echinocandins, that are not efflux pump substrates provide one option. Potential therapeutic approaches that could overcome azole resistance include targeting efflux pump transcriptional regulators and fungal stress response pathways, blockade of energy supply, and direct inhibition of efflux pumps.
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Affiliation(s)
- Richard D Cannon
- Department of Oral Sciences, School of Dentistry, University of Otago, P.O. Box 647, Dunedin 9054, New Zealand.
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184
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Moon CJ, Shin JH, Kim DW, Kee SJ, Kim SH, Shin MG, Suh SP, Ryang DW. Species-Specific Differences in Rhodamine 6G Accumulation of Candida Isolates Detected by Flow Cytometric Analysis. Ann Lab Med 2009; 29:127-34. [DOI: 10.3343/kjlm.2009.29.2.127] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Affiliation(s)
- Chang Jin Moon
- Department of Laboratory Medicine, Chonnam National University Medical School, Gwangju, Korea
| | - Jong Hee Shin
- Department of Laboratory Medicine, Chonnam National University Medical School, Gwangju, Korea
| | - Da Woon Kim
- Department of Laboratory Medicine, Chonnam National University Medical School, Gwangju, Korea
| | - Seung Jung Kee
- Department of Laboratory Medicine, Chonnam National University Medical School, Gwangju, Korea
| | - Soo Hyun Kim
- Department of Laboratory Medicine, Chonnam National University Medical School, Gwangju, Korea
| | - Myung Geun Shin
- Department of Laboratory Medicine, Chonnam National University Medical School, Gwangju, Korea
| | - Soon Pal Suh
- Department of Laboratory Medicine, Chonnam National University Medical School, Gwangju, Korea
| | - Dong Wook Ryang
- Department of Laboratory Medicine, Chonnam National University Medical School, Gwangju, Korea
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185
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Batová M, Dzugasová V, Borecká S, Goffa E, Oblasová Z, Subík J. Molecular and phenotypic analysis of mutations causing anionic phospholipid deficiency in closely related yeast species. Folia Microbiol (Praha) 2009; 54:30-6. [PMID: 19330542 DOI: 10.1007/s12223-009-0005-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2008] [Revised: 10/20/2008] [Indexed: 10/21/2022]
Abstract
The pel1 mutation in Saccharomyces cerevisiae and the Cgpgs1Delta mutation in Candida glabrata result in deficiency of mitochondrial phosphatidylglycerolphosphate synthase and lack of two anionic phospholipids, phosphatidylglycerol and cardiolipin. DNA sequence analysis of the PCR-amplified pel1 mutant allele revealed that the pel1 mutation resulted from a single amino-acid substitution (Glu(463)Lys) in the C-terminal part of encoded enzyme. The CgPGS1 gene cloned in a centromeric pFL38 vector functionally complemented the pel1 mutation in S. cerevisiae. Likewise, the ScPGS1 gene cloned in pCgACU5 plasmid fully complemented the Cgpgs1Delta mutation in C. glabrata. This mutation increased the cell surface hydrophobicity and decreased biofilm formation. These results support a close evolutionary relatedness of S. cerevisiae and C. glabrata and point to the relationship between expression of virulence factors and anionic phospholipid deficiency in pathogenic C. glabrata.
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Affiliation(s)
- M Batová
- Department of Microbiology and Virology, Comenius University, Bratislava, Slovakia
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186
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Kolaczkowski M, Kolaczkowska A, Stermitz FR. Modulation of the Antifungal Activity of New Medicinal Plant Extracts Active onCandida glabrataby the Major Transporters and Regulators of the Pleiotropic Drug-Resistance Network inSaccharomyces cerevisiae. Microb Drug Resist 2009; 15:11-7. [DOI: 10.1089/mdr.2009.0854] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
| | - Anna Kolaczkowska
- Faculty of Veterinary Medicine, Wroclaw University of Environmental and Life Sciences, Wroclaw, Poland
| | - Frank R. Stermitz
- Department of Chemistry, Colorado State University, Fort Collins, Colorado
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187
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Mutations in the CgPDR1 and CgERG11 genes in azole-resistant Candida glabrata clinical isolates from Slovakia. Int J Antimicrob Agents 2009; 33:574-8. [PMID: 19196495 DOI: 10.1016/j.ijantimicag.2008.11.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2008] [Revised: 11/21/2008] [Accepted: 11/24/2008] [Indexed: 11/22/2022]
Abstract
Candida glabrata is an important human pathogen that is naturally less susceptible to antimycotics compared with Candida albicans. Ten unmatched C. glabrata clinical isolates were selected from a collection of isolates exhibiting decreased susceptibilities to azole antifungals. Overexpression of the CgPDR1 gene, encoding the main multidrug resistance transcription factor, and its target genes CgCDR1 and CgCDR2, coding for drug efflux transporters, was observed in six fluconazole-resistant isolates. Sequence analysis of the polymerase chain reaction (PCR)-amplified DNA fragments of each isolate's CgPDR1 gene was used to identify two novel L347F and H576Y mutations in CgPdr1p. These proved to be responsible for fluconazole resistance in transformants of the C. glabrata pdr1Delta mutant strain. Five isolates harbouring the H576Y mutation also contained the mutation E502V in CgErg11p 14C-lanosterol-demethylase. Heterologous expression of the CgERG11 mutant allele did not provide evidence for its involvement in azole resistance. In four fluconazole-sensitive isolates that were itraconazole-resistant, slightly enhanced CgCDR2 expression was observed. No upregulation of the CgERG11 gene was observed in any of the ten isolates. The results demonstrate that decreased susceptibilities of C. glabrata clinical isolates to azole antifungals mainly results from gain-of-function mutations in the gene encoding the CgPdr1p transcription factor.
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188
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Ferrari S, Ischer F, Calabrese D, Posteraro B, Sanguinetti M, Fadda G, Rohde B, Bauser C, Bader O, Sanglard D. Gain of function mutations in CgPDR1 of Candida glabrata not only mediate antifungal resistance but also enhance virulence. PLoS Pathog 2009; 5:e1000268. [PMID: 19148266 PMCID: PMC2607542 DOI: 10.1371/journal.ppat.1000268] [Citation(s) in RCA: 209] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2008] [Accepted: 12/15/2008] [Indexed: 11/20/2022] Open
Abstract
CgPdr1p is a Candida glabrata Zn(2)-Cys(6) transcription factor involved in the regulation of the ABC-transporter genes CgCDR1, CgCDR2, and CgSNQ2, which are mediators of azole resistance. Single-point mutations in CgPDR1 are known to increase the expression of at least CgCDR1 and CgCDR2 and thus to contribute to azole resistance of clinical isolates. In this study, we investigated the incidence of CgPDR1 mutations in a large collection of clinical isolates and tested their relevance, not only to azole resistance in vitro and in vivo, but also to virulence. The comparison of CgPDR1 alleles from azole-susceptible and azole-resistant matched isolates enabled the identification of 57 amino acid substitutions, each positioned in distinct CgPDR1 alleles. These substitutions, which could be grouped into three different “hot spots,” were gain of function (GOF) mutations since they conferred hyperactivity to CgPdr1p revealed by constitutive high expression of ABC-transporter genes. Interestingly, the major transporters involved in azole resistance (CgCDR1, CgCDR2, and CgSNQ2) were not always coordinately expressed in presence of specific CgPDR1 GOF mutations, thus suggesting that these are rather trans-acting elements (GOF in CgPDR1) than cis-acting elements (promoters) that lead to azole resistance by upregulating specific combinations of ABC-transporter genes. Moreover, C. glabrata isolates complemented with CgPDR1 hyperactive alleles were not only more virulent in mice than those with wild type alleles, but they also gained fitness in the same animal model. The presence of CgPDR1 hyperactive alleles also contributed to fluconazole treatment failure in the mouse model. In conclusion, this study shows for the first time that CgPDR1 mutations are not only responsible for in vitro/in vivo azole resistance but that they can also confer a selective advantage under host conditions. Candida glabrata is a yeast causing several diseases in humans and especially in immuno-compromised people. C. glabrata infections are treated with antifungal agents, however the use of some agents, for example azoles, is associated with the development of resistance. In this yeast species, azole resistance is mediated almost exclusively by ATP Binding Cassette (ABC) multidrug transporters. Their overexpression results in enhanced efflux of azoles and thus generates resistance. Regulation of ABC transporters is therefore of pivotal importance to understanding azole resistance. In C. glabrata, the expression of ABC transporters is mediated by a zinc finger transcription factor called CgPDR1. Gain of function (GOF) mutations in CgPDR1 result in high ABC transporter expression. In this study, we investigated the occurrence of GOF mutations in a large collection of azole-resistant isolates and found a high variety of mutations localized in three distinct domains of CgPDR1. We found that these mutations are not only associated with resistance but also enhanced virulence and fitness of C. glabrata in animal models. Our study provides for the first time evidence that mutations causing antifungal resistance can also provide a selective advantage under host conditions and thus highlights the need of carefully monitoring resistance in this pathogen.
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Affiliation(s)
- Sélène Ferrari
- Institute of Microbiology, University of Lausanne and University Hospital Center, Lausanne, Switzerland
| | - Françoise Ischer
- Institute of Microbiology, University of Lausanne and University Hospital Center, Lausanne, Switzerland
| | - David Calabrese
- Institute of Microbiology, University of Lausanne and University Hospital Center, Lausanne, Switzerland
| | - Brunella Posteraro
- Institute of Microbiology, Università Cattolica del Sacro Cuore, Rome, Italy
| | | | - Giovanni Fadda
- Institute of Microbiology, Università Cattolica del Sacro Cuore, Rome, Italy
| | | | | | - Oliver Bader
- Institut für Medizinische Mikrobiologie, Universitätskliniken Göttingen, Göttingen, Germany
| | - Dominique Sanglard
- Institute of Microbiology, University of Lausanne and University Hospital Center, Lausanne, Switzerland
- * E-mail:
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189
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Shahi P, Moye-Rowley WS. Coordinate control of lipid composition and drug transport activities is required for normal multidrug resistance in fungi. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2008; 1794:852-9. [PMID: 19150512 DOI: 10.1016/j.bbapap.2008.12.012] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2008] [Revised: 12/12/2008] [Accepted: 12/15/2008] [Indexed: 10/21/2022]
Abstract
Pathogenic fungi present a special problem in the clinic as the range of drugs that can be used to treat these types of infections is limited. This situation is further complicated by the presence of robust inducible gene networks encoding different proteins that confer tolerance to many available antifungal drugs. The transcriptional control of these multidrug resistance systems in several key fungi will be discussed. Experiments in the non-pathogenic Saccharomyces cerevisiae have provided much of our current understanding of the molecular framework on which fungal multidrug resistance is built. More recent studies on the important pathogenic Candida species, Candida albicans and Candida glabrata, have provided new insights into the organization of the multidrug resistance systems in these organisms. We will compare the circuitry of multidrug resistance networks in these three organisms and suggest that, in addition to the well-accepted drug efflux activities, the regulation of membrane composition by multidrug resistance proteins provides an important contribution to the resistant phenotypes observed.
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Affiliation(s)
- Puja Shahi
- Department of Molecular Physiology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
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190
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Tumbarello M, Sanguinetti M, Trecarichi EM, La Sorda M, Rossi M, de Carolis E, de Gaetano Donati K, Fadda G, Cauda R, Posteraro B. Fungaemia caused by Candida glabrata with reduced susceptibility to fluconazole due to altered gene expression: risk factors, antifungal treatment and outcome. J Antimicrob Chemother 2008; 62:1379-85. [DOI: 10.1093/jac/dkn381] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
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191
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Antifungal resistance of Candida glabrata vaginal isolates and development of a quantitative reverse transcription-PCR-based azole susceptibility assay. Antimicrob Agents Chemother 2008; 52:3424-6. [PMID: 18591262 DOI: 10.1128/aac.00462-08] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
A multiplex quantitative reverse transcription-PCR assay was developed to detect azole resistance in Candida glabrata, an important opportunistic pathogen that develops resistance rapidly. Resistance was defined as a >or=3-fold increase in CDR1 expression by this assay, which proved to be 100% sensitive and 95% specific in comparison to the gold standard broth microdilution assay.
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192
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Meletiadis J, Chanock S, Walsh TJ. Defining targets for investigating the pharmacogenomics of adverse drug reactions to antifungal agents. Pharmacogenomics 2008; 9:561-84. [DOI: 10.2217/14622416.9.5.561] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Adverse drug reactions (ADRs) associated with antifungal therapy are major problems in patients with invasive fungal infections. Whether by clinical history or patterns of genetic variation, the identification of patients at risk for ADRs should result in improved outcomes while minimizing deleterious side effects. A major contributing factor to ADRs with antifungal agents relates to drug distribution, metabolism and excretion. Genetic variation in key genes can alter the structure and expression of genes and gene products (e.g., proteins). Thus far, the effort has focused on identifying polymorphisms with either empirical or predicted in silico functional consequences; the best candidate genes encode phase I and II drug-metabolizing enzymes (e.g., CYP2C19 and N-acetyltransferase), plasma proteins (albumin and lipoproteins) and drug transporters (P-glycoprotein and multidrug resistance proteins), which can affect the disposition of antifungal agents, eventually leading to dose-dependent (type A) toxicity. Less is known regarding the key genes that interact with antifungal agents, resulting in idiosyncratic (type B) ADRs. The possible role of certain gene products and genetic polymorphisms in the toxicities of antifungal agents are discussed in this review. The preliminary data address the following: low-density lipoproteins and cholesteryl ester transfer protein in amphotericin B renal toxicity; toll-like receptor 1 and 2 in amphotericin B infusion-related ADRs; phosphodiesterase 6 in voriconazole visual adverse events; flavin-containing monooxygenase, glutathione transferases and multidrug resistance proteins 1 and 2 in ketoconazole and terbinafine hepatotoxicity; CYP enzymes and P-glycoprotein in drug interactions between azoles and coadministered medications; multidrug resistance proteins 8 and 9 on 5-flucytosine bone marrow toxicity; and mast cell activation in caspofungin histamine release. This will focus on high-priority candidate genes, which could provide a starting point for molecular studies to elucidate the potential mechanisms for understanding toxicity associated with antifungal drugs as well as identifying candidate genes for large population prospective genetic association studies.
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Affiliation(s)
- Joseph Meletiadis
- National Cancer Institute, National Institutes of Health, Pediatric Oncology Branch, Bethesda, MD 20814, USA
- Attikon University General Hospital, Laboratoty for Clinical Microbiology, 1 Rimini Street, Athens 124 62, Greece
| | - Stephen Chanock
- National Cancer Institute, National Institutes of Health, Pediatric Oncology Branch, Bethesda, MD 20814, USA
| | - Thomas J Walsh
- National Cancer Institute, National Institutes of Health, Pediatric Oncology Branch, Bethesda, MD 20814, USA
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193
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Paquet V, Volmer AA, Carreira EM. Synthesis and in vitro biological properties of novel cationic derivatives of amphotericin B. Chemistry 2008; 14:2465-81. [PMID: 18196508 DOI: 10.1002/chem.200701237] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Novel cationic amphotericin B derivatives as highly potent antifungal agents are reported. These semi-synthetic derivatives of amphotericin B were elaborated through a series of modifications both on the nitrogen atom of the mycosamine and on the C-16 carboxylic acid moiety. The antifungal activity of the new conjugates was tested against Saccharomyces cerevisiae and also against nine different strains of Candida albicans and Candida glabrata, including an amphotericin resistant strain. High potency was observed in the case of polyamine derivatives bearing two 3-aminopropyl chains on the mycosamine. The evaluation of the biological properties also included the determination of the hemolytic activity of the compounds by measuring the EH50 values.
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Affiliation(s)
- Valérie Paquet
- Laboratorium für Organische Chemie, ETH Zürich, HCI H335, 8093 Zürich, Switzerland
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194
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Batova M, Borecka-Melkusova S, Simockova M, Dzugasova V, Goffa E, Subik J. Functional characterization of the CgPGS1 gene reveals a link between mitochondrial phospholipid homeostasis and drug resistance in Candida glabrata. Curr Genet 2008; 53:313-22. [PMID: 18343926 DOI: 10.1007/s00294-008-0187-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2008] [Revised: 03/04/2008] [Accepted: 03/05/2008] [Indexed: 10/22/2022]
Abstract
Cardiolipin and its precursor phosphatidylglycerol are two anionic phospholipids that are essential for the biogenesis of functional mitochondria. To assess their role in mitochondrial and cellular functions in the pathogenic yeast Candida glabrata, a functional characterization of the CgPGS1 gene encoding the phosphatidylglycerolphosphate synthase has been carried out. Transposon insertion mutation in CgPGS1 resulted in the loss of phosphatidylglycerolphosphate synthase activity and in deficiency of both phosphatidylglycerol and cardiolipin. The Cgpgs1 Delta mutant cells displayed reduced amounts of cytochrome b and cytochrome a, and had impaired growth on minimal media containing non-fermentable carbon and energy sources. They did not grow at elevated temperatures and failed to form colonies after induction of mitochondrial DNA deletions. The mutant cells also displayed a decreased susceptibility to fluconazole, ketoconazole, clotrimazole, voriconazole and posaconazole. In the Cgpgs1 Delta mutant, a quantitative real time PCR revealed enhanced mRNA levels for multidrug resistance associated genes such as CgPDR1 encoding transcriptional activator and CgCDR1, CgPDH1 and CgSNQ2 coding for drug efflux transporters. These results indicate that CgPGS1 and anionic phospholipids are required for optimal mitochondrial functions and maintenance of yeast susceptibility to azole antifungals.
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Affiliation(s)
- Monika Batova
- Department of Microbiology and Virology, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynska dolina B-2, 842 15 Bratislava 4, Slovak Republic
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195
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Survey of vaginal-flora Candida species isolates from women of different age groups by use of species-specific PCR detection. J Clin Microbiol 2008; 46:1501-3. [PMID: 18305136 DOI: 10.1128/jcm.02485-07] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
A retrospective survey of 93,775 samples testing positive in Candida species-specific PCR tests performed on cervicovaginal swabs over a 4-year period demonstrated consistent yearly distributions of Candida albicans (89%), C. glabrata (7.9%), C. parapsilosis (1.7%), and C. tropicalis (1.4%). However, the species distributions among different age groups revealed increases in the percentages of non-albicans species with increases in age.
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196
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Torelli R, Posteraro B, Ferrari S, La Sorda M, Fadda G, Sanglard D, Sanguinetti M. The ATP-binding cassette transporter-encoding gene CgSNQ2 is contributing to the CgPDR1-dependent azole resistance of Candida glabrata. Mol Microbiol 2008; 68:186-201. [PMID: 18312269 DOI: 10.1111/j.1365-2958.2008.06143.x] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Our previous investigation on Candida glabrata azole-resistant isolates identified two isolates with unaltered expression of CgCDR1/CgCDR2, but with upregulation of another ATP-binding cassette transporter, CgSNQ2, which is a gene highly similar to ScSNQ2 from Saccharomyces cerevisiae. One of the two isolates (BPY55) was used here to elucidate this phenomenon. Disruption of CgSNQ2 in BPY55 decreased azole resistance, whereas reintroduction of the gene in a CgSNQ2 deletion mutant fully reversed this effect. Expression of CgSNQ2 in a S. cerevisiae strain lacking PDR5 mediated not only resistance to azoles but also to 4-nitroquinoline N-oxide, which is a ScSNQ2-specific substrate. A putative gain-of-function mutation, P822L, was identified in CgPDR1 from BPY55. Disruption of CgPDR1 in BPY55 conferred enhanced azole susceptibility and eliminated CgSNQ2 expression, whereas introduction of the mutated allele in a susceptible strain where CgPDR1 had been disrupted conferred azole resistance and CgSNQ2 upregulation, indicating that CgSNQ2 was controlled by CgPDR1. Finally, CgSNQ2 was shown to be involved in the in vivo response to fluconazole. Together, our data first demonstrate that CgSNQ2 contributes to the development of CgPDR1-dependent azole resistance in C. glabrata. The overlapping in function and regulation between CgSNQ2 and ScSNQ2 further highlight the relationship between S. cerevisiae and C. glabrata.
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Affiliation(s)
- Riccardo Torelli
- Institute of Microbiology, Università Cattolica del Sacro Cuore, Rome, Italy
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197
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Selection of a surrogate agent (fluconazole or voriconazole) for initial susceptibility testing of posaconazole against Candida spp.: results from a global antifungal surveillance program. J Clin Microbiol 2007; 46:551-9. [PMID: 18094129 DOI: 10.1128/jcm.01952-07] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
There are currently no FDA-approved broth microdilution antifungal susceptibility testing products or interpretive breakpoints for susceptibility testing of the new triazole posaconazole. Fluconazole and voriconazole are in the same triazole class as posaconazole, have CLSI-approved interpretive MIC breakpoints, and are available on some commercially available MIC panels. We investigated whether one or both of these agents may be useful as a surrogate marker for posaconazole susceptibility. Fluconazole, voriconazole, and posaconazole MIC results for 10,807 isolates of Candida spp. were analyzed to validate a potential surrogate marker for posaconazole activity against indicated species. For illustrative purposes, we applied the voriconazole MIC breakpoints to posaconazole (susceptible, < or =1 microg/ml; susceptible dose dependent, 2 microg/ml; resistant, > or =4 microg/ml) and compared these MIC results and categorical interpretations with those of fluconazole and voriconazole by using regression statistics and categorical agreement. For all 10,807 isolates, the absolute categorical agreement was 91.1% (0.1% very major errors [VME], 1.2% major errors [ME], and 7.6% minor errors [M]) using fluconazole as the surrogate marker and 97.7% (0.3% VME 0.1% ME, and 1.9% M) using voriconazole as the surrogate. The results with fluconazole improved to a categorical agreement of 93.7% (0.1% VME, 0.2% ME, and 6.0% M) when results for Candida krusei (not indicated for fluconazole testing) were omitted. Either fluconazole or voriconazole MIC results may serve as surrogate markers to predict the susceptibility of Candida spp. to posaconazole.
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198
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Ray D, Goswami R, Dadhwal V, Goswami D, Banerjee U, Kochupillai N. Prolonged (3-month) mycological cure rate after boric acid suppositories in diabetic women with vulvovaginal candidiasis. J Infect 2007; 55:374-7. [PMID: 17692922 DOI: 10.1016/j.jinf.2007.06.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2007] [Revised: 05/28/2007] [Accepted: 06/08/2007] [Indexed: 01/07/2023]
Abstract
OBJECTIVE Patients with diabetes mellitus (DM) are at increased risk of vulvovaginal candidiasis (VVC) due to C. glabrata. In our previous study we had shown that patients with diabetes mellitus and VVC show an overall superior mycological cure rate (74% versus 51%) with boric acid therapy at 15th day as compared to fluconazole. Present study was carried out to assess long term response to boric acid in diabetic women with VVC. MATERIAL AND METHODS Subjects included 40 consecutive diabetic women (type 2 DM=26 and type 1 DM=14) who had achieved mycological cure (high vaginal swab culture negativity) on day 15 of therapy following single-dose oral-150 mg fluconazole (n=21) or 600 mg of boric acid suppositories given daily for 14 days (n=19). At third month of follow up, patients were assessed for signs and symptoms of VVC and a repeat HVS was collected for fungal culture. HbA1c was measured to assess glycaemic control. RESULTS The mean age, BMI, HBA1c and frequency of various Candida species isolated at initial diagnosis were comparable in the fluconazole and boric acid treatment groups. Fifteen of 21 (71.4%) and 12 of 19 (63.1%) women who achieved mycological cure at 15 day remain cured at three months in the fluconazole and boric acid treated groups, respectively (P=0.83). With 74% mycological cure at 15th day, this would indicate that on an average only 46.6% of diabetic women with VVC would remain cured at 3 months after a course of 14 days boric acid therapy. Most of the patients relapsed with no change in Candida species. The demographic profile and mean HbA1c (8.6+/-2.2 versus 8.8+/-2.4%, P=0.83) were comparable in patients with (n=27) and without mycological cure (n=13). CONCLUSION The results of the current study indicating comparable mycological cure rate at 3 months between fluconazole and boric acid treated patients would support use of boric acid in the acute management of VVC in view of its superior short term response in diabetic women with C. glabrata infections. However, there is need to explore other therapeutic regimens which are effective in achieving long term mycological cure in diabetic women with VVC.
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Affiliation(s)
- Debarti Ray
- Department of Endocrinology and Metabolism, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110029, India.
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199
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Shin JH, Chae MJ, Song JW, Jung SI, Cho D, Kee SJ, Kim SH, Shin MG, Suh SP, Ryang DW. Changes in karyotype and azole susceptibility of sequential bloodstream isolates from patients with Candida glabrata candidemia. J Clin Microbiol 2007; 45:2385-91. [PMID: 17581937 PMCID: PMC1951250 DOI: 10.1128/jcm.00381-07] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We examined the changes in genotypes and azole susceptibilities among sequential bloodstream isolates of Candida glabrata during the course of fungemia and the relationship of these changes to antifungal therapy. Forty-one isolates were obtained from 15 patients (9 patients who received antifungal therapy and 6 patients who did not) over periods of up to 36 days. The isolates were analyzed using pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) and tested for antifungal susceptibility to fluconazole, itraconazole, and voriconazole. PFGE typing consisted of electrophoretic karyotyping and restriction endonuclease analysis of genomic DNA by use of NotI (REAG-N). The 41 isolates yielded 23 different karyotypes and 11 different REAG-N patterns but only 3 MLST types. The sequential strains from each patient had identical or similar REAG-N patterns. However, they had two or three different karyotypes in 6 (40%) of 15 patients. The isolates from these six patients exhibited the same or similar azole susceptibilities, and five patients did not receive antifungal therapy. Development of acquired azole resistance in sequential isolates was detected for only one patient. For this patient, an isolate of the same genotype obtained after azole therapy showed three- or fourfold increases in the MICs of all three azole antifungals and exhibited increased expression of the CgCDR1 efflux pump. This study shows that karyotypic changes can develop rapidly among sequential bloodstream strains of C. glabrata from the same patient without antifungal therapy. In addition, we confirmed that C. glabrata could acquire azole resistance during the course of fungemia in association with azole therapy.
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Affiliation(s)
- Jong Hee Shin
- Department of Laboratory Medicine, Chonnam National University Medical School, 8 Hakdong Dongku, Gwangju 501-757, South Korea.
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200
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Genome-wide expression profiling of the response to terbinafine in Candida albicans using a cDNA microarray analysis. Chin Med J (Engl) 2007. [DOI: 10.1097/00029330-200705010-00013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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