Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 12 de 12
Filter
Add more filters










Publication year range
1.
Mycopathologia ; 183(4): 701-708, 2018 Aug.
Article in English | MEDLINE | ID: mdl-29725811

ABSTRACT

Candida parapsilosis sensu stricto is an emerging cause of hospital-acquired Candida infections, predominantly in southern Europe, South America, and Asia. We investigated the genetic diversity and antifungal susceptibility profile of 170 independent C. parapsilosis sensu stricto strains obtained from patients with candidemia who were treated at the Ege University Hospital in Izmir, Turkey, between 2006 and 2014. The identity of each strain was confirmed via PCR amplification and digestion of the secondary alcohol dehydrogenase-encoding gene. The 24-h geometric mean minimum inhibitory concentrations of the antifungal agents, in increasing order, were as follows: posaconazole, 0.10 µg/mL; voriconazole, 0.21 µg/mL; caspofungin, 0.38 µg/mL; amphotericin B, 0.61 µg/mL; anidulafungin, 0.68 µg/mL; and fluconazole, 2.95 µg/mL. Microsatellite genotyping of the isolates (using fluorescently labeled primers and a panel of four different short-nucleotide repeat fragments) identified 25, 17, 17, and 8 different allelic genotypes at the CP6, B5, CP4, and CP1 locus, respectively. Posaconazole, caspofungin, and amphotericin B showed the greatest in vitro activity of the tested systemic azole, echinocandin, and polyene agents, respectively, and the observed antifungal susceptibility of the isolates was shown to be independent of their isolation source. We obtained a combined discriminatory power of 0.99 with a total of 130 genotypes for 170 isolates tested. Finally, microsatellite profiling analysis confirmed the presence of identical genotype between separate isolates, supporting that effective surveillance and infection-prevention programs are essential to limit the impact of C. parapsilosis sensu stricto on hospitalized patients' health.


Subject(s)
Candida parapsilosis/classification , Candida parapsilosis/drug effects , Candidemia/microbiology , Drug Resistance, Fungal , Genetic Variation , Alcohol Dehydrogenase/genetics , Antifungal Agents/pharmacology , Candida parapsilosis/genetics , Candida parapsilosis/isolation & purification , Fungal Proteins/genetics , Genotype , Hospitals, University , Humans , Microbial Sensitivity Tests , Microsatellite Repeats , Polymerase Chain Reaction , Turkey
2.
J Fungi (Basel) ; 4(1)2018 Jan 23.
Article in English | MEDLINE | ID: mdl-29371509

ABSTRACT

Clinically relevant members of the fungal genus, Fusarium, exhibit an extraordinary genetic diversity and cause a wide spectrum of infections in both healthy individuals and immunocompromised patients. Generally, Fusarium species are intrinsically resistant to all systemic antifungals. We investigated whether the presence or absence of the ability to produce biofilms across and within Fusarium species complexes is linked to higher resistance against antifungals. A collection of 41 Fusarium strains, obtained from 38 patients with superficial and systemic infections, and three infected crops, were tested, including 25 species within the Fusarium fujikuroi species complex, 14 from the Fusarium solani species complex (FSSC), one Fusarium dimerum species complex, and one Fusarium oxysporum species complex isolate. Of all isolates tested, only seven strains from two species of FSSC, five F. petroliphilum and two F. keratoplasticum strains, recovered from blood, nail scrapings, and nasal biopsy samples, could produce biofilms under the tested conditions. In the liquid culture tested, sessile biofilm-forming Fusarium strains exhibited elevated minimum inhibitory concentrations (MICs) for amphotericin B, voriconazole, and posaconazole, compared to their planktonic counterparts, indicating that the ability to form biofilm may significantly increase resistance. Collectively, this suggests that once a surface adherent biofilm has been established, therapies designed to kill planktonic cells of Fusarium are ineffective.

3.
Article in English | MEDLINE | ID: mdl-28264849

ABSTRACT

Aspergillus flavus has been frequently reported as the leading cause of invasive aspergillosis in certain tropical and subtropical countries. Two hundred A. flavus strains originating from clinical and environmental sources and collected between 2008 and 2015 were phylogenetically identified at the species level by analyzing partial ß-tubulin and calmodulin genes. In vitro antifungal susceptibility testing was performed against antifungals using the European Committee on Antimicrobial Susceptibility Testing (EUCAST) broth microdilution method. In addition, genotyping was performed using a short-tandem-repeat (STR) assay of a panel of six microsatellite markers (A. flavus 2A, 2B, 2C, 3A, 3B, and 3C), in order to determine the genetic variation and the potential relationship between clinical and environmental isolates. The geometric means of the minimum inhibitory concentrations/minimum effective concentrations (MICs/MECs) of the antifungals across all isolates were (in increasing order): posaconazole, 0.13 mg/liter; anidulafungin, 0.16 mg/liter; itraconazole, 0.29 mg/liter; caspofungin, 0.42 mg/liter; voriconazole, 0.64 mg/liter; isavuconazole, 1.10 mg/liter; amphotericin B, 3.35 mg/liter; and flucytosine, 62.97 mg/liter. All of the clinical isolates were genetically different. However, an identical microsatellite genotype was found between a clinical isolate and two environmental strains. In conclusion, posaconazole and anidulafungin showed the greatest in vitro activity among systemic azoles and echinocandins, respectively. However, the majority of the A. flavus isolates showed reduced susceptibility to amphotericin B. Antifungal susceptibility of A. flavus was not linked with the clinical or environmental source of isolation. Microsatellite genotyping may suggest an association between clinical and environmental strains, although this requires further investigation.


Subject(s)
Antifungal Agents/pharmacology , Aspergillus flavus , Genetic Variation/genetics , Microsatellite Repeats/genetics , Aspergillosis/microbiology , Aspergillus flavus/drug effects , Aspergillus flavus/genetics , Aspergillus flavus/isolation & purification , Calmodulin/genetics , Genotype , Humans , Microbial Sensitivity Tests , Tubulin/genetics
4.
Article in English | MEDLINE | ID: mdl-27956429

ABSTRACT

Trichophyton schoenleinii is an anthropophilic dermatophyte mainly causing tinea favosa of the scalp in certain regions of the world, especially Africa and Asia. We investigated the in vitro susceptibilities of 55 T. schoenleinii isolates collected over the last 30 years from Iran, Turkey, and China to 12 antifungals using the CLSI broth microdilution method. Our results revealed that terbinafine and ketoconazole were the most potent antifungal agents among those tested, independently of the geographic regions where strains were isolated.


Subject(s)
Antifungal Agents/pharmacology , Tinea Favosa/microbiology , Trichophyton/drug effects , China , Humans , Iran , Ketoconazole/pharmacology , Microbial Sensitivity Tests , Naphthalenes/pharmacology , Terbinafine , Trichophyton/isolation & purification , Turkey
5.
Methods Mol Biol ; 1508: 107-139, 2017.
Article in English | MEDLINE | ID: mdl-27837500

ABSTRACT

By definition, an antifungal agent is a drug that selectively destroys fungal pathogens with minimal side effects to the host. Despite an increase in the prevalence of fungal infections particularly in immunocompromised patients, only a few classes of antifungal drugs are available for therapy, and they exhibit limited efficacy in the treatment of life-threatening infections. These drugs include polyenes, azoles, echinocandins, and nucleoside analogs. This chapter focuses on the currently available classes and representatives of systemic antifungal drugs in clinical use. We further discuss the unmet clinical needs in the antifungal research field; efforts in reformulation of available drugs such as Amphotericin B nanoparticles for oral drug delivery; development of new agents of known antifungal drug classes, such as albaconazole, SCY-078, and biafungin; and new drugs with novel targets for treatment of invasive fungal infections, including nikkomycin Z, sordarin derivatives, VT-1161 and VT-1129, F901318, VL-2397, and T-2307.


Subject(s)
Antifungal Agents/pharmacology , Mycoses/drug therapy , Animals , Antifungal Agents/therapeutic use , Drug Discovery , Drug Resistance, Fungal , Fungi/drug effects , Humans , Mycoses/microbiology
6.
Expert Rev Clin Pharmacol ; 10(2): 225-237, 2017 Feb.
Article in English | MEDLINE | ID: mdl-27868472

ABSTRACT

INTRODUCTION: Dermatophytosis is generally defined as an infection of the hair, nails, or glabrous skin. These infections are caused by the keratinophilic fungi Trichophyton spp., Microsporum spp., and Epidermophyton, which have been recovered from both symptomatic and asymptomatic individuals. Although dermatophytosis is generally not a life-threatening condition, these types of infections are among the most common infections worldwide, and their incidence has continued to increase consistently in recent years. Area covered: This article provides an overview of the general characteristics of dermatophytes, including their taxonomy and epidemiology, as well as the different clinical forms and laboratory diagnostics of dermatophytosis. We further classify the topical and systemic antifungal compounds currently used to treat dermatophyte infections. Expert commentary: Antifungal therapy is a central component of patient management for dermatophytosis, and depending on the strategy chosen, topical and/or systemic drugs can be used. However, for effective treatment, it is important to correctly determine the causal agents at the species level, which will enable administration of suitable therapeutics and initiation of appropriate management strategies.


Subject(s)
Antifungal Agents/administration & dosage , Antifungal Agents/therapeutic use , Dermatomycoses/drug therapy , Administration, Topical , Humans
7.
J Clin Microbiol ; 54(11): 2798-2803, 2016 11.
Article in English | MEDLINE | ID: mdl-27605714

ABSTRACT

In a retrospective multicenter study, 102 formalin-fixed paraffin-embedded (FFPE) tissue specimens with histopathology results were tested. Two 4- to 5-µm FFPE tissue sections from each specimen were digested with proteinase K, followed by automated nucleic acid extraction. Multiple real-time quantitative PCR (qPCR) assays targeting the internal transcribed spacer 2 (ITS2) region of ribosomal DNA, using fluorescently labeled primers, was performed to identify clinically important genera and species of Aspergillus, Fusarium, Scedosporium, and the Mucormycetes The molecular identification was correlated with results from histological examination. One of the main findings of our study was the high sensitivity of the automated DNA extraction method, which was estimated to be 94%. The qPCR procedure that was evaluated identified a range of fungal genera/species, including Aspergillus fumigatus, Aspergillus flavus, Aspergillus terreus, Aspergillus niger, Fusarium oxysporum, Fusarium solani, Scedosporium apiospermum, Rhizopus oryzae, Rhizopus microsporus, Mucor spp., and Syncephalastrum Fusarium oxysporum and F. solani DNA was amplified from five specimens from patients initially diagnosed by histopathology as having aspergillosis. Aspergillus flavus, S. apiospermum, and Syncephalastrum were detected from histopathological mucormycosis samples. In addition, examination of four samples from patients suspected of having concomitant aspergillosis and mucormycosis infections resulted in the identification of two A. flavus isolates, one Mucor isolate, and only one sample having both R. oryzae and A. flavus Our results indicate that histopathological features of molds may be easily confused in tissue sections. The qPCR assay used in this study is a reliable tool for the rapid and accurate identification of fungal pathogens to the genus and species levels directly from FFPE tissues.


Subject(s)
Aspergillus/isolation & purification , Fusarium/isolation & purification , Mucorales/isolation & purification , Mycoses/diagnosis , Pathology, Molecular/methods , Real-Time Polymerase Chain Reaction/methods , Scedosporium/isolation & purification , Aspergillus/genetics , Automation, Laboratory/methods , DNA, Ribosomal Spacer/chemistry , DNA, Ribosomal Spacer/genetics , Diagnosis, Differential , Disinfectants , Fixatives , Formaldehyde , Fusarium/genetics , Humans , Mucorales/genetics , Paraffin , Scedosporium/genetics , Specimen Handling/methods , Tissue Fixation
8.
Antimicrob Agents Chemother ; 60(1): 387-92, 2016 01.
Article in English | MEDLINE | ID: mdl-26525787

ABSTRACT

We employed an endpoint genotyping method to update the prevalence rate of positivity for the TR34/L98H mutation (a 34-bp tandem repeat mutation in the promoter region of the cyp51A gene in combination with a substitution at codon L98) and the TR46/Y121F/T289A mutation (a 46-bp tandem repeat mutation in the promoter region of the cyp51A gene in combination with substitutions at codons Y121 and T289) among clinical Aspergillus fumigatus isolates obtained from different regions of Iran over a recent 5-year period (2010 to 2014). The antifungal activities of itraconazole, voriconazole, and posaconazole against 172 clinical A. fumigatus isolates were investigated using the European Committee on Antimicrobial Susceptibility Testing (EUCAST) broth microdilution method. For the isolates with an azole resistance phenotype, the cyp51A gene and its promoter were amplified and sequenced. In addition, using a LightCycler 480 real-time PCR system, a novel endpoint genotyping analysis method targeting single-nucleotide polymorphisms was evaluated to detect the L98H and Y121F mutations in the cyp51A gene of all isolates. Of the 172 A. fumigatus isolates tested, the MIC values of itraconazole (≥16 mg/liter) and voriconazole (>4 mg/liter) were high for 6 (3.5%). Quantitative analysis of single-nucleotide polymorphisms showed the TR34/L98H mutation in the cyp51A genes of six isolates. No isolates harboring the TR46/Y121F/T289A mutation were detected. DNA sequencing of the cyp51A gene confirmed the results of the novel endpoint genotyping method. By microsatellite typing, all of the azole-resistant isolates had genotypes different from those previously recovered from Iran and from the Dutch TR34/L98H controls. In conclusion, there was not a significant increase in the prevalence of azole-resistant A. fumigatus isolates harboring the TR34/L98H resistance mechanism among isolates recovered over a recent 5-year period (2010 to 2014) in Iran. A quantitative assay detecting a single-nucleotide polymorphism in the cyp51A gene of A. fumigatus is a reliable tool for the rapid screening and monitoring of TR34/L98H- and TR46/Y121F/T289A-positive isolates and can easily be incorporated into clinical mycology algorithms.


Subject(s)
Antifungal Agents/therapeutic use , Aspergillus fumigatus/genetics , Cytochrome P-450 Enzyme System/genetics , Drug Resistance, Fungal/genetics , Fungal Proteins/genetics , Polymorphism, Single Nucleotide , Aspergillosis/drug therapy , Aspergillosis/epidemiology , Aspergillosis/microbiology , Aspergillus fumigatus/drug effects , Aspergillus fumigatus/enzymology , Aspergillus fumigatus/isolation & purification , Cytochrome P-450 Enzyme System/metabolism , DNA, Fungal/genetics , Fungal Proteins/metabolism , Gene Expression , Humans , Iran/epidemiology , Itraconazole/therapeutic use , Microbial Sensitivity Tests , Microsatellite Repeats , Mycological Typing Techniques , Promoter Regions, Genetic , Retrospective Studies , Sequence Analysis, DNA , Triazoles/therapeutic use , Voriconazole/therapeutic use
9.
PLoS Biol ; 13(11): e1002302, 2015 Nov.
Article in English | MEDLINE | ID: mdl-26569493

ABSTRACT

[This corrects the article DOI: 10.1371/journal.pbio.1001206.].

10.
PLoS Genet ; 9(5): e1003424, 2013 May.
Article in English | MEDLINE | ID: mdl-23658527

ABSTRACT

Canonical Wnt signaling plays a rate-limiting role in regulating self-renewal and differentiation in mouse embryonic stem cells (ESCs). We have previously shown that mutation in the Apc (adenomatous polyposis coli) tumor suppressor gene constitutively activates Wnt signaling in ESCs and inhibits their capacity to differentiate towards ecto-, meso-, and endodermal lineages. However, the underlying molecular and cellular mechanisms through which Wnt regulates lineage differentiation in mouse ESCs remain to date largely unknown. To this aim, we have derived and studied the gene expression profiles of several Apc-mutant ESC lines encoding for different levels of Wnt signaling activation. We found that down-regulation of Tcf3, a member of the Tcf/Lef family and a key player in the control of self-renewal and pluripotency, represents a specific and primary response to Wnt activation in ESCs. Accordingly, rescuing Tcf3 expression partially restored the neural defects observed in Apc-mutant ESCs, suggesting that Tcf3 down-regulation is a necessary step towards Wnt-mediated suppression of neural differentiation. We found that Tcf3 down-regulation in the context of constitutively active Wnt signaling does not result from promoter DNA methylation but is likely to be caused by a plethora of mechanisms at both the RNA and protein level as shown by the observed decrease in activating histone marks (H3K4me3 and H3-acetylation) and the upregulation of miR-211, a novel Wnt-regulated microRNA that targets Tcf3 and attenuates early neural differentiation in mouse ESCs. Our data show for the first time that Wnt signaling down-regulates Tcf3 expression, possibly at both the transcriptional and post-transcriptional levels, and thus highlight a novel mechanism through which Wnt signaling inhibits neuro-ectodermal lineage differentiation in mouse embryonic stem cells.


Subject(s)
Basic Helix-Loop-Helix Transcription Factors/genetics , Cell Differentiation , Embryonic Stem Cells/physiology , Wnt Signaling Pathway , Adenomatous Polyposis Coli Protein/genetics , Animals , Basic Helix-Loop-Helix Transcription Factors/metabolism , Cell Lineage , DNA Methylation , Down-Regulation , Embryonic Stem Cells/cytology , Gene Expression Regulation, Developmental , Mice , Mutation , Transcription, Genetic
11.
PLoS Genet ; 9(5): e1003503, 2013 May.
Article in English | MEDLINE | ID: mdl-23696748

ABSTRACT

B lymphopoiesis is the result of several cell-commitment, lineage-choice, and differentiation processes. Every differentiation step is characterized by the activation of a new, lineage-specific, genetic program and the extinction of the previous one. To date, the central role of specific transcription factors in positively regulating these distinct differentiation processes to acquire a B cell-specific genetic program is well established. However, the existence of specific transcriptional repressors responsible for the silencing of lineage inappropriate genes remains elusive. Here we addressed the molecular mechanism behind repression of non-lymphoid genes in B cells. We report that the histone deacetylase HDAC7 was highly expressed in pre-B cells but dramatically down-regulated during cellular lineage conversion to macrophages. Microarray analysis demonstrated that HDAC7 re-expression interfered with the acquisition of the gene transcriptional program characteristic of macrophages during cell transdifferentiation; the presence of HDAC7 blocked the induction of key genes for macrophage function, such as immune, inflammatory, and defense response, cellular response to infections, positive regulation of cytokines production, and phagocytosis. Moreover, re-introduction of HDAC7 suppressed crucial functions of macrophages, such as the ability to phagocytose bacteria and to respond to endotoxin by expressing major pro-inflammatory cytokines. To gain insight into the molecular mechanisms mediating HDAC7 repression in pre-B cells, we undertook co-immunoprecipitation and chromatin immunoprecipitation experimental approaches. We found that HDAC7 specifically interacted with the transcription factor MEF2C in pre-B cells and was recruited to MEF2 binding sites located at the promoters of genes critical for macrophage function. Thus, in B cells HDAC7 is a transcriptional repressor of undesirable genes. Our findings uncover a novel role for HDAC7 in maintaining the identity of a particular cell type by silencing lineage-inappropriate genes.


Subject(s)
Cell Transdifferentiation/genetics , Histone Deacetylases/genetics , Lymphopoiesis , Macrophages/cytology , Precursor Cells, B-Lymphoid/cytology , B-Lymphocytes/cytology , B-Lymphocytes/metabolism , Binding Sites , Cell Differentiation , Cell Lineage , Down-Regulation , Histone Deacetylases/metabolism , Humans , MADS Domain Proteins/metabolism , MEF2 Transcription Factors , Macrophages/metabolism , Myeloid Cells/cytology , Myeloid Cells/metabolism , Myogenic Regulatory Factors/metabolism , Precursor Cells, B-Lymphoid/metabolism , Promoter Regions, Genetic
12.
PLoS Biol ; 9(11): e1001206, 2011 Nov.
Article in English | MEDLINE | ID: mdl-22140357

ABSTRACT

Persistence of a reservoir of latently infected memory T cells provides a barrier to HIV eradication in treated patients. Several reports have implicated the involvement of SWI/SNF chromatin remodeling complexes in restricting early steps in HIV infection, in coupling the processes of integration and remodeling, and in promoter/LTR transcription activation and repression. However, the mechanism behind the seemingly contradictory involvement of SWI/SNF in the HIV life cycle remains unclear. Here we addressed the role of SWI/SNF in regulation of the latent HIV LTR before and after transcriptional activation. We determined the predicted nucleosome affinity of the LTR sequence and found a striking reverse correlation when compared to the strictly positioned in vivo LTR nucleosomal structure; sequences encompassing the DNase hypersensitive regions displayed the highest nucleosome affinity, while the strictly positioned nucleosomes displayed lower affinity for nucleosome formation. To examine the mechanism behind this reverse correlation, we used a combinatorial approach to determine DNA accessibility, histone occupancy, and the unique recruitment and requirement of BAF and PBAF, two functionally distinct subclasses of SWI/SNF at the LTR of HIV-infected cells before and after activation. We find that establishment and maintenance of HIV latency requires BAF, which removes a preferred nucleosome from DHS1 to position the repressive nucleosome-1 over energetically sub-optimal sequences. Depletion of BAF resulted in de-repression of HIV latency concomitant with a dramatic alteration in the LTR nucleosome profile as determined by high resolution MNase nucleosomal mapping. Upon activation, BAF was lost from the HIV promoter, while PBAF was selectively recruited by acetylated Tat to facilitate LTR transcription. Thus BAF and PBAF, recruited during different stages of the HIV life cycle, display opposing function on the HIV promoter. Our data point to the ATP-dependent BRG1 component of BAF as a putative therapeutic target to deplete the latent reservoir in patients.


Subject(s)
Chromosomal Proteins, Non-Histone/physiology , HIV Long Terminal Repeat/genetics , HIV-1/physiology , Human Immunodeficiency Virus Proteins/physiology , Nucleosomes/physiology , Virus Latency , Acetylation , Chromatin Assembly and Disassembly , Chromosomal Proteins, Non-Histone/antagonists & inhibitors , Chromosomal Proteins, Non-Histone/genetics , Gene Expression Regulation, Viral , HIV-1/genetics , Human Immunodeficiency Virus Proteins/antagonists & inhibitors , Human Immunodeficiency Virus Proteins/genetics , Humans , Jurkat Cells , Models, Genetic , Promoter Regions, Genetic , T-Lymphocytes/virology , Transcriptional Activation , Virus Activation/genetics , tat Gene Products, Human Immunodeficiency Virus/metabolism , tat Gene Products, Human Immunodeficiency Virus/physiology
SELECTION OF CITATIONS
SEARCH DETAIL
...