Acquisition of flucytosine, azole, and caspofungin resistance in Candida glabrata bloodstream isolates serially obtained from a hematopoietic stem cell transplant recipient.
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ABSTRACT:
SUBMITTER: Chapeland-Leclerc F
PROVIDER: S-EPMC2826023 | biostudies-literature | 2010 Mar
REPOSITORIES: biostudies-literature
Publications
Acquisition of flucytosine, azole, and caspofungin resistance in Candida glabrata bloodstream isolates serially obtained from a hematopoietic stem cell transplant recipient.
Chapeland-Leclerc Florence F Hennequin Christophe C Papon Nicolas N Noël Thierry T Girard Aurélie A Socié Gérard G Ribaud Patricia P Lacroix Claire C
Antimicrobial agents and chemotherapy 20091228 3
We describe the acquisition of flucytosine, azole, and caspofungin resistance in sequential Candida glabrata bloodstream isolates collected from a bone marrow transplant patient with clinical failure. Point mutations in C. glabrata FUR1 (CgFUR1) and CgFKS2 and overexpression of CgCDR1 and CgCDR2 were observed in resistant isolates. ...[more]
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Project description:Infections with the opportunistic yeast Candida glabrata have increased dramatically in recent years. Antifungal therapy of yeast infections commonly employs azoles, such as fluconazole (FLC), but C. glabrata frequently develops resistance to these inhibitors of ergosterol biosynthesis. The pyrimidine analog flucytosine (5-fluorocytosine [5FC]) is highly active versus C. glabrata but is now rarely used clinically due to similar concerns over resistance and, a related concern, the toxicity associated with high doses used to counter resistance. Azole-5FC combination therapy would potentially address these concerns; however, previous studies suggest that 5FC may antagonize azole activity versus C. glabrata. Here, we report that 5FC at subinhibitory concentrations antagonized the activity of FLC 4- to 16-fold versus 8 of 8 C. glabrata isolates tested. 5FC antagonized the activity of other azoles similarly but had only indifferent effects in combination with unrelated antifungals. Since azole resistance in C. glabrata results from transcription factor Pdr1-dependent upregulation of the multidrug transporter gene CDR1, we reasoned that 5FC antagonism might be similarly mediated. Indeed, 5FC-FLC antagonism was abrogated in pdr1Δ and cdr1Δ strains. In further support of this hypothesis, 5FC exposure induced CDR1 expression 6-fold, and this upregulation was Pdr1 dependent. In contrast to azoles, 5FC is not a Cdr1 substrate and so its activation of Pdr1 was unexpected. We observed, however, that 5FC exposure readily induced petite mutants, which exhibit Pdr1-dependent CDR1 upregulation. Thus, mitochondrial dysfunction resulting in Pdr1 activation is the likely basis for 5FC antagonism of azole activity versus C. glabrata.
| S-EPMC3811237 | biostudies-literature
Project description:Microarray was used to analyze azole resistance of Candida glabrata oropharyngeal isolates from 7 hematopoietic stem cell transplant recipients receiving fluconazole prophylaxis. Transcriptional profiling of the sequential-paired clinical isolates by microarray revealed 19 genes upregulated in the majority of resistant isolates compared to their paired-susceptible isolates. All seven resistant isolates had greater than two fold upregulation of CgPDR1, a master transcriptional regulator of PDR network, and all 7 resistant isolates showed upregulation of known CgPDR1-target genes. The altered transcriptome can be explained in part by the observation that all 7 resistant isolates had acquired a single nonsynonymous mutation in their CgPDR1 ORF. Four mutations occurred in the regulatory domain (L280P, L344S, G348A, S391L) and one in the activation domain (G943S) while two mutations (N764I, 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 and five resistant isolates into a laboratory azole-sensitive strain (cgpdr1) 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 background, upregulation of CgPDR1 and CgPDR1-target genes varied between the 5 transformants, independent of the domain locations in which the mutations occurred. In sum, gain-of-function mutations in CgPDR1 not only contributed to the clinical azole resistance but different mutations had varying degrees of impact on the CgPDR1-target genes.
2010-07-07 | GSE21355 | GEO
Project description:Two isolates of Candida glabrata, one susceptible and one resistant to azole antifungals, were previously shown to differ in quantity and activity of the cytochrome P-450 14alpha-lanosterol demethylase which is the target for azole antifungals. The resistant isolate also had a lower intracellular level of fluconazole, but not of ketoconazole or itraconazole, than the susceptible isolate. In the present study a 3.7-fold increase in the copy number of the CYP51 gene, encoding the 14alpha-lanosterol demethylase, was found. The amount of CYP51 mRNA transcript in the resistant isolate was eight times greater than it was in the susceptible isolate. Hybridization experiments on chromosomal blots indicated that this increase in copy number was due to duplication of the entire chromosome containing the CYP51 gene. The phenotypic instability of the resistant isolate was demonstrated genotypically: a gradual loss of the duplicated chromosome was seen in successive subcultures of the isolate in fluconazole-free medium and correlated with reversion to susceptibility. The greater abundance of the amplified chromosome induced pronounced differences in the protein patterns of the susceptible and revertant isolates versus that of the resistant isolate, as demonstrated by two-dimensional gel electrophoresis (2D-GE). Densitometry of the 2D-GE product indicated upregulation of at least 25 proteins and downregulation of at least 76 proteins in the resistant isolate.
| S-EPMC164098 | biostudies-other
Project description:Candida glabrata has been often isolated from AIDS patients with oropharyngeal candidiasis treated with azole antifungal agents, especially fluconazole. We recently showed that the ATP-binding-cassette (ABC) transporter gene CgCDR1 was upregulated in C. glabrata clinical isolates resistant to azole antifungal agents (D. Sanglard, F. Ischer, D. Calabrese, P. A. Majcherczyk, and J. Bille, Antimicrob. Agents Chemother. 43:2753-2765, 1999). Deletion of CgCDR1 in C. glabrata rendered the null mutant hypersusceptible to azole derivatives and showed the importance of this gene in mediating azole resistance. We observed that wild-type C. glabrata exposed to fluconazole in a medium containing the drug at 50 microg/ml developed resistance to this agent and other azoles at a surprisingly high frequency (2 x 10(-4) to 4 x 10(-4)). We show here that this high-frequency azole resistance (HFAR) acquired in vitro was due, at least in part, to the upregulation of CgCDR1. The CgCDR1 deletion mutant DSY1041 could still develop HFAR but in a medium containing fluconazole at 5 microg/ml. In the HFAR strain derived from DSY1041, a distinct ABC transporter gene similar to CgCDR1, called CgCDR2, was upregulated. This gene was slightly expressed in clinical isolates but was upregulated in strains with the HFAR phenotype. Deletion of both CgCDR1 and CgCDR2 suppressed the development of HFAR in a medium containing fluconazole at 5 microg/ml, showing that both genes are important mediators of resistance to azole derivatives in C. glabrata. We also show here that the HFAR phenomenon was linked to the loss of mitochondria in C. glabrata. Mitochondrial loss could be obtained by treatment with ethidium bromide and resulted in acquisition of resistance to azole derivatives without previous exposure to these agents. Azole resistance obtained in vitro by HFAR or by agents stimulating mitochondrial loss was at least linked to the upregulation of both CgCDR1 and CgCDR2.
| S-EPMC90441 | biostudies-literature
Project description:We previously showed that resistant colonies of Candida glabrata inside the azole inhibition zones had respiratory deficiency due to mutations in mitochondrial DNA. Here, we analyzed the mechanisms of azole resistance in petite mutants of C. glabrata obtained by exposure to fluconazole or induced by ethidium bromide. The respiratory deficiency of these mutants was confirmed by oxygraphy and flow cytometric analysis with rhodamine 123, and its mitochondrial origin was demonstrated by transmission electron microscopy and restriction endonuclease analysis of the mitochondrial DNA. Flow cytometry with rhodamine 6G suggested an increased drug efflux in mutant cells, which was further supported by Northern blot analysis of the expression of the C. glabrata CDR1 (CgCDR1) and CgCDR2 genes, encoding efflux pumps. Conversely, the expression of CgERG11, which encodes the azole target, was not affected by petite mutations, and no differences were seen in the sequence of this gene between parent isolates and mutants. Moreover, sterol analysis showed similar overall amount of sterols in parent and mutant cells, but quantitative modifications were observed in the mutants, with almost undetectable biosynthesis intermediates. Further analysis performed after separation of free sterols from steryl esters revealed a defect in sterol esterification in mutant cells, with free ergosterol representing 92% of the overall sterol content. Thus, resistance or decreased susceptibility to azoles in petite mutants of C. glabrata is associated with increased expression of CgCDR1 and, to a lesser extent, of CgCDR2. In addition, the marked increase in free ergosterol content would explain their increased susceptibility to polyenes.
| S-EPMC400549 | biostudies-literature
Project description:BACKGROUND:Antifungal resistance rates are increasing. We investigated the mechanisms of azole resistance of Candida spp. bloodstream isolates obtained from a surveillance study conducted between 2012 and 2015. METHODS:Twenty-six azole non-susceptible Candida spp. clinical isolates were investigated. Antifungal susceptibilities were determined using the Sensititre YeastOne® YO10 panel. The ERG11 gene was amplified and sequenced to identify amino acid polymorphisms, while real-time PCR was utilised to investigate the expression levels of ERG11, CDR1, CDR2 and MDR1. RESULTS:Azole cross-resistance was detected in all except two isolates. Amino acid substitutions (A114S, Y257H, E266D, and V488I) were observed in all four C. albicans tested. Of the 17 C. tropicalis isolates, eight (47%) had ERG11 substitutions, of which concurrent observation of Y132F and S154F was the most common. A novel substitution (I166S) was detected in two of the five C. glabrata isolates. Expression levels of the various genes differed between the species but CDR1 and CDR2 overexpression appeared to be more prominent in C. glabrata. CONCLUSIONS:There was interplay of various different mechanisms, including mechanisms which were not studied here, responsible for azole resistance in Candida spp in our study.
| S-EPMC6337757 | biostudies-literature
Project description:Microarray was used to analyze azole resistance of Candida glabrata oropharyngeal isolates from 7 hematopoietic stem cell transplant recipients receiving fluconazole prophylaxis. Transcriptional profiling of the sequential-paired clinical isolates by microarray revealed 19 genes upregulated in the majority of resistant isolates compared to their paired-susceptible isolates. All seven resistant isolates had greater than two fold upregulation of CgPDR1, a master transcriptional regulator of PDR network, and all 7 resistant isolates showed upregulation of known CgPDR1-target genes. The altered transcriptome can be explained in part by the observation that all 7 resistant isolates had acquired a single nonsynonymous mutation in their CgPDR1 ORF. Four mutations occurred in the regulatory domain (L280P, L344S, G348A, S391L) and one in the activation domain (G943S) while two mutations (N764I, 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 and five resistant isolates into a laboratory azole-sensitive strain (cgpdr1) 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 background, upregulation of CgPDR1 and CgPDR1-target genes varied between the 5 transformants, independent of the domain locations in which the mutations occurred. In sum, gain-of-function mutations in CgPDR1 not only contributed to the clinical azole resistance but different mutations had varying degrees of impact on the CgPDR1-target genes.
2010-07-07 | GSE21352 | GEO
Project description:Echinocandins, including caspofungin (CSP) and micafungin (MCF), are highly active versus Candida glabrata (MIC of ≤0.06 μg/ml). True resistance (MIC of ≥1 μg/ml) is a rare event and strictly associated with mutations in β-1,3-glucan synthase gene FKS1 or FKS2. In contrast, we show here that mutants exhibiting reduced susceptibility to CSP (CRS; MICs of 0.12 to 0.5 μg/ml) are readily selected in vitro and, paradoxically, demonstrate increased susceptibility to MCF (MIS) ranging from 4- to 32-fold. CRS-MIS mutants were generated from all 10 C. glabrata strains tested and were tentatively identified within a collection of clinical isolates. Intriguingly, sequencing and gene disruption demonstrated that CRS-MIS is Fks independent.
| S-EPMC3147630 | biostudies-literature
Project description:The opportunistic yeast pathogen Candida glabrata is recognized for its ability to acquire resistance during prolonged treatment with azole antifungals (J. E. Bennett, K. Izumikawa, and K. A. Marr. Antimicrob. Agents Chemother. 48:1773-1777, 2004). Resistance to azoles is largely mediated by the transcription factor PDR1, resulting in the upregulation of ATP-binding cassette (ABC) transporter proteins and drug efflux. Studies in the related yeast Saccharomyces cerevisiae have shown that Pdr1p forms a heterodimer with another transcription factor, Stb5p. In C. glabrata, the open reading frame (ORF) designated CAGL0I02552g has 38.8% amino acid identity with STB5 (YHR178w) and shares an N-terminal Zn(2)Cys(6) binuclear cluster domain and a fungus-specific transcriptional factor domain, prompting us to test for homologous function and a possible role in azole resistance. Complementation of a Δyhr178w (Δstb5) mutant with CAGL0I02552g resolved the increased sensitivity to cold, hydrogen peroxide, and caffeine of the mutant, for which reason we designated CAGl0I02552g CgSTB5. Overexpression of CgSTB5 in C. glabrata repressed azole resistance, whereas deletion of CgSTB5 caused a modest increase in resistance. Expression analysis found that CgSTB5 shares many transcriptional targets with CgPDR1 but, unlike the latter, is a negative regulator of pleiotropic drug resistance, including the ABC transporter genes CDR1, PDH1, and YOR1.
| S-EPMC3553707 | biostudies-literature
Project description:Microarray was used to analyze azole resistance of Candida glabrata oropharyngeal isolates from 7 hematopoietic stem cell transplant recipients receiving fluconazole prophylaxis. Transcriptional profiling of the sequential-paired clinical isolates by microarray revealed 19 genes upregulated in the majority of resistant isolates compared to their paired-susceptible isolates. All seven resistant isolates had greater than two fold upregulation of CgPDR1, a master transcriptional regulator of PDR network, and all 7 resistant isolates showed upregulation of known CgPDR1-target genes. The altered transcriptome can be explained in part by the observation that all 7 resistant isolates had acquired a single nonsynonymous mutation in their CgPDR1 ORF. Four mutations occurred in the regulatory domain (L280P, L344S, G348A, S391L) and one in the activation domain (G943S) while two mutations (N764I, 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 and five resistant isolates into a laboratory azole-sensitive strain (cgpdr1) 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 background, upregulation of CgPDR1 and CgPDR1-target genes varied between the 5 transformants, independent of the domain locations in which the mutations occurred. In sum, gain-of-function mutations in CgPDR1 not only contributed to the clinical azole resistance but different mutations had varying degrees of impact on the CgPDR1-target genes. Two groups (C1S/84 and C16R/84) consisted of 4 biological replicates in which a complemented strain sample was paired with the laboratory wild type strain 84 sample. Each group included 1 reciprocally labeled sample.
2010-07-07 | E-GEOD-21355 | biostudies-arrayexpress