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Drug-resistant Candida glabrata infection in cancer patients.

ABSTRACT: Cancer patients are at risk for candidemia, and increasing Candida spp. resistance poses an emerging threat. We determined rates of antifungal drug resistance, identified factors associated with resistance, and investigated the correlation between resistance and all-cause mortality rates among cancer patients with ≥1 C. glabrata-positive blood culture at MD Anderson Cancer Center, Houston, Texas, USA, during March 2005-September 2013. Of 146 isolates, 30 (20.5%) were resistant to fluconazole, 15 (10.3%) to caspofungin, and 10 (6.8%) to multiple drugs (9 caspofungin-resistant isolates were also resistant to fluconazole, 1 to amphotericin B). Independently associated with fluconazole resistance were azole preexposure, hematologic malignancy, and mechanical ventilation. Independently associated with caspofungin resistance were echinocandin preexposure, monocytopenia, and total parenteral nutrition. Fluconazole resistance was highly associated with caspofungin resistance, independent of prior azole or echinocandin use. Caspofungin resistance was associated with increased 28-day all-cause mortality rates. These findings highlight the need for good stewardship of antifungal drugs.

SUBMITTER: Farmakiotis D

PROVIDER: S-EPMC4214312 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Functional information from clinically-derived drug resistant forms of the Candida glabrata Pdr1 transcription factor.

Project description:Azole drugs are the most frequently used antifungal agents. The pathogenic yeast Candida glabrata acquires resistance to azole drugs via single amino acid substitution mutations eliciting a gain-of-function (GOF) hyperactive phenotype in the Pdr1 transcription factor. These GOF mutants constitutively drive high transcription of target genes such as the ATP-binding cassette transporter-encoding CDR1 locus. Previous characterization of Pdr1 has demonstrated that this factor is negatively controlled by the action of a central regulatory domain (CRD) of ~700 amino acids, in which GOF mutations are often found. Our earlier experiments demonstrated that a Pdr1 derivative in which the CRD was deleted gave rise to a transcriptional regulator that could not be maintained as the sole copy of PDR1 in the cell owing to its toxically high activity. Using a set of GOF PDR1 alleles from azole-resistant clinical isolates, we have analyzed the mechanisms acting to repress Pdr1 transcriptional activity. Our data support the view that Pdr1-dependent transactivation is mediated by a complex network of transcriptional coactivators interacting with the extreme C-terminal part of Pdr1. These coactivators include but are not limited to the Mediator component Med15A. Activity of this C-terminal domain is controlled by the CRD and requires multiple regions across the C-terminus for normal function. We also provide genetic evidence for an element within the transactivation domain that mediates the interaction of Pdr1 with coactivators on one hand while restricting Pdr1 activity on the other hand. These data indicate that GOF mutations in PDR1 block nonidentical negative inputs that would otherwise restrain Pdr1 transcriptional activation. The strong C-terminal transactivation domain of Pdr1 uses multiple different protein regions to recruit coactivators.

| S-EPMC7473514 | biostudies-literature

Molecular biological characterization of an azole-resistant Candida glabrata isolate.

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

Emerging echinocandin-resistant Candida albicans and glabrata in Switzerland.

Project description:Echinocandins represent the first-line therapy of candidemia. Echinocandin resistance among Candida spp. is mainly due to acquired FKS mutations. In this study, we report the emergence of FKS-mutant Candida albicans/glabrata in Switzerland and provide the microbiological and clinical characteristics of 9 candidemic episodes. All patients were previously exposed to echinocandins (median 26 days; range 15-77). Five patients received initial echinocandin therapy with persistent candidemia in 4 of them. Overall mortality was 33%.

| S-EPMC7518979 | biostudies-literature

Emergence of resistant <i>Candida glabrata</i> in Germany.

Project description:BackgroundCandida glabrata is the second leading fungal pathogen causing candidaemia and invasive candidiasis in Europe. This yeast is recognized for its rapid ability to acquire antifungal drug resistance.ObjectivesWe systematically evaluated 176 C. glabrata isolates submitted to the German National Reference Center for Invasive Fungal Infections (NRZMyk) between 2015 and 2019 with regard to echinocandin and fluconazole susceptibility.MethodsSusceptibility testing was performed using a reference protocol (EUCAST) and a range of commercial assays. Hot spot regions of the echinocandin target FKS genes were sequenced using Sanger sequencing.ResultsIn total, 84 of 176 isolates were initially classified as anidulafungin-resistant based on EUCAST testing. Of those, 71 harboured mutations in the glucan synthase encoding FKS genes (13% in FKS1, 87% in FKS2). Significant differences in anidulafungin MICs were found between distinct mutation sites. 11 FKS wild-type (WT) isolates initially classified as resistant exhibited anidulafungin MICs fluctuating around the interpretation breakpoint upon re-testing with multiple assays. Two FKS WT isolates consistently showed high anidulafungin MICs and thus must be considered resistant despite the absence of target gene mutations. Over one-third of echinocandin-resistant strains displayed concomitant fluconazole resistance. Of those, isolates linked to bloodstream infection carrying a change at Ser-663 were associated with adverse clinical outcome.ConclusionsResistant C. glabrata strains are emerging in Germany. Phenotypic echinocandin testing can result in misclassification of susceptible strains. FKS genotyping aids in detecting these strains, however, echinocandin resistance may occur despite a wild-type FKS genotype.

| S-EPMC8346698 | biostudies-literature

Fluconazole-Resistant Candida glabrata Bloodstream Isolates, South Korea, 2008-2018.

Project description: Not available

| S-EPMC7920659 | biostudies-literature

Deletion of ADA2 Increases Antifungal Drug Susceptibility and Virulence in Candida glabrata.

Project description:Candida glabrata, the second most frequent cause of candidiasis after Candida albicans, is an emerging human fungal pathogen that is intrinsically drug tolerant. Currently, studies of C. glabrata genes involved in drug tolerance are limited. Ada2, a component serving as a transcription adaptor of the Spt-Ada-Gcn5 acetyltransferase (SAGA) complex, is required for antifungal drug tolerance and virulence in C. albicans However, its roles in C. glabrata remain elusive. In this study, we found that ada2 mutants demonstrated severe growth defects at 40°C but only mild defects at 37°C or 25°C. In addition, C. glabrata ada2 mutants exhibited pleiotropic phenotypes, including susceptibility to three classes of antifungal drugs (i.e., azoles, echinocandins, and polyenes) and cell wall-perturbing agents but resistance to the endoplasmic reticulum stressor tunicamycin. According to RNA sequence analysis, the expression of 43 genes was downregulated and the expression of 442 genes was upregulated in the ada2 mutant compared to their expression in the wild type. C. glabrata ADA2, along with its downstream target ERG6, controls antifungal drug tolerance and cell wall integrity. Surprisingly, ada2 mutants were hypervirulent in a murine model of systemic infection, possibly due to the upregulation of multiple adhesin-like genes, increased agar invasion, and overstimulation of murine tumor necrosis factor alpha production.

| S-EPMC5826168 | biostudies-literature

Histone Acetylation Regulator Gcn5 Mediates Drug Resistance and Virulence of Candida glabrata.

Project description:Candida glabrata is poised to adapt to drug pressure rapidly and acquire antifungal resistance leading to therapeutic failure. Given the limited antifungal armamentarium, there is an unmet need to explore new targets or therapeutic strategies for antifungal treatment. The lysine acetyltransferase Gcn5 has been implicated in the pathogenesis of C. albicans. Yet how Gcn5 functions and impacts antifungal resistance in C. glabrata is unknown. Disrupting GCN5 rendered C. glabrata cells more sensitive to various stressors, partially reverted resistance in drug-resistant mutants, and attenuated the emergence of resistance compared to wild-type cells. RNA sequencing (RNA-seq) analysis revealed transcriptomic changes involving multiple biological processes and different transcriptional responses to antifungal drugs in gcn5Δ cells compared to wild-type cells. GCN5 deletion also resulted in reduced intracellular survival within THP-1 macrophages. In summary, Gcn5 plays a critical role in modulating the virulence of C. glabrata and regulating its response to antifungal pressure and host defense. IMPORTANCE As an important and successful human pathogen, Candida glabrata is known for its swift adaptation and rapid acquisition of resistance to the most commonly used antifungal agents, resulting in therapeutic failure in clinical settings. Here, we describe that the histone acetyltransferase Gcn5 is a key factor in adapting to antifungal pressure and developing resistance in C. glabrata. The results provide new insights into epigenetic control over the drug response in C. glabrata and may be useful for drug target discovery and the development of new therapeutic strategies to combat fungal infections.

| S-EPMC9241792 | biostudies-literature

Contribution of CgPDR1-regulated genes in enhanced virulence of azole-resistant Candida glabrata.

Project description: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 PDR1 upregulated 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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Evolution of drug-resistant and virulent small colonies in phenotypically diverse populations of the human fungal pathogen <i>Candida glabrata</i>.

Project description:Antimicrobial resistance frequently carries a fitness cost to a pathogen, measured as a reduction in growth rate compared to the sensitive wild-type, in the absence of antibiotics. Existing empirical evidence points to the following relationship between cost of resistance and virulence. If a resistant pathogen suffers a fitness cost in terms of reduced growth rate it commonly has lower virulence compared to the sensitive wild-type. If this cost is absent so is the reduction in virulence. Here we show, using experimental evolution of drug resistance in the fungal human pathogen Candida glabrata, that reduced growth rate of resistant strains need not result in reduced virulence. Phenotypically heterogeneous populations were evolved in parallel containing highly resistant sub-population small colony variants (SCVs) alongside sensitive sub-populations. Despite their low growth rate in the absence of an antifungal drug, the SCVs did not suffer a marked alteration in virulence compared with the wild-type ancestral strain, or their co-isolated sensitive strains. This contrasts with classical theory that assumes growth rate to positively correlate with virulence. Our work thus highlights the complexity of the relationship between resistance, basic life-history traits and virulence.

| S-EPMC7423662 | biostudies-literature

Prevalent mutator genotype identified in fungal pathogen Candida glabrata promotes multi-drug resistance.

Project description:The fungal pathogen Candida glabrata has emerged as a major health threat since it readily acquires resistance to multiple drug classes, including triazoles and/or echinocandins. Thus far, cellular mechanisms promoting the emergence of resistance to multiple drug classes have not been described in this organism. Here we demonstrate that a mutator phenotype caused by a mismatch repair defect is prevalent in C. glabrata clinical isolates. Strains carrying alterations in mismatch repair gene MSH2 exhibit a higher propensity to breakthrough antifungal treatment in vitro and in mouse models of colonization, and are recovered at a high rate (55% of all C. glabrata recovered) from patients. This genetic mechanism promotes the acquisition of resistance to multiple antifungals, at least partially explaining the elevated rates of triazole and multi-drug resistance associated with C. glabrata. We anticipate that identifying MSH2 defects in infecting strains may influence the management of patients on antifungal drug therapy.

| S-EPMC5603725 | biostudies-literature

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