scholarly journals Inhibition of Vesicular Transport Influences Fungal Susceptibility to Fluconazole

2019 ◽  
Vol 63 (5) ◽  
Author(s):  
Liesbeth Demuyser ◽  
Katrien Van Dyck ◽  
Bea Timmermans ◽  
Patrick Van Dijck
Keyword(s):  
Fungal Infections ◽  
Vesicular Transport ◽  
Model Organism ◽  
Specific Inhibitor ◽  
New Drugs ◽  
Transport Pathway ◽  
Fluconazole Resistance ◽  
Content Type ◽  
Development Of Resistance ◽  
Novel Therapeutic Strategies

ABSTRACTFungal infections pose a substantial threat to the human population. They can cause either mild and relatively harmless infections or invasive and often lethal diseases in patients with a weakened immune system. The majority of these human fungal infections are caused byCandidaspecies. The limited amount of available therapies, together with the development of resistance against these drugs, strongly emphasizes the need for novel therapeutic strategies. As it is quite time-consuming to introduce completely new drugs to the market, potentiating the efficacy of existing drugs would be a better strategy. Therefore, it is important to identify cellular pathways involved in the development of drug resistance. We found that vesicular transport is involved in fungal susceptibility to the most widely used antifungal drug, fluconazole. We identified specific complexes in the vesicular transport pathway which contribute to fluconazole resistance or tolerance in the model organismSaccharomyces cerevisiae. Furthermore, we confirmed our findings in the clinically relevant fungiCandida albicansandCandida glabrata. Finally, we show that the combination of fluconazole with a specific inhibitor of the vesicular transport pathway increases the susceptibility ofCandidaspecies, indicating the potential of using vesicular transport as a target in combination therapy.

scholarly journals Oxadiazole-Containing Macrocyclic Peptides Potentiate Azole Activity against Pathogenic Candida Species

mSphere ◽  
2020 ◽  
Vol 5 (2) ◽  
Author(s):  
Nicole M. Revie ◽  
Nicole Robbins ◽  
Luke Whitesell ◽  
John R. Frost ◽  
Solomon D. Appavoo ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Fungal Pathogens ◽  
Fungal Infections ◽  
Candida Auris ◽  
Peptide Backbone ◽  
Fungal Cell ◽  
Content Type ◽  
Development Of Resistance ◽  
Macrocyclic Peptides ◽  
Novel Therapeutic Strategies

ABSTRACT Opportunistic pathogens of the genus Candida reign as the leading cause of mycotic disease and are associated with mortality rates greater than 40%, even with antifungal intervention. This is in part due to the limited arsenal of antifungals available to treat systemic fungal infections. Azoles have been the most widely deployed class of antifungal drug for decades and function by targeting the biosynthesis of ergosterol, a key component of the fungal cell membrane. However, their utility is compromised by their fungistatic nature, which favors the development of resistance. Combination therapy has the potential to confer enhanced efficacy as well as mitigate the evolution of resistance. Previously, we described the generation of structurally diverse macrocyclic peptides with a 1,3,4-oxadiazole and an endocyclic amine grafted within the peptide backbone. Importantly, this noncanonical backbone displayed high membrane permeability, an important attribute for compounds that need to permeate across the fungal cell wall and membrane in order to reach their intracellular target. Here, we explored the bioactivity of this novel chemical scaffold on its own and in combination with the azole fluconazole. Although few of the oxadiazole-containing macrocyclic peptides displayed activity against Candida albicans on their own, many increased the efficacy of fluconazole, resulting in a synergistic combination that was independent of efflux inhibition. Interestingly, these molecules also enhanced azole activity against several non-albicans Candida species, including the azole-resistant pathogens Candida glabrata and Candida auris. This work characterizes a novel chemical scaffold that possesses azole-potentiating activity against clinically important Candida species. IMPORTANCE Fungal infections, such as those caused by pathogenic Candida species, pose a serious threat to human health. Treating these infections relies heavily on the use of azole antifungals; however, resistance to these drugs develops readily, demanding novel therapeutic strategies. This study characterized the antifungal activity of a series of molecules that possess unique chemical attributes and the ability to traverse cellular membranes. We observed that many of the compounds increased the activity of the azole fluconazole against Candida albicans, without blocking the action of drug efflux pumps. These molecules also increased the efficacy of azoles against other Candida species, including the emerging azole-resistant pathogen Candida auris. Thus, we describe a novel chemical scaffold with broad-spectrum bioactivity against clinically important fungal pathogens.

scholarly journals Hypoxanthine-Guanine Phosphoribosyltransferase Is Dispensable for Mycobacterium smegmatis Viability

2019 ◽  
Vol 202 (5) ◽  
Author(s):  
Zdeněk Knejzlík ◽  
Klára Herkommerová ◽  
Dana Hocková ◽  
Iva Pichová
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Mycobacterium Smegmatis ◽  
Model Organism ◽  
Specific Inhibitor ◽  
Purine Salvage ◽  
Content Type ◽  
Acyclic Nucleoside Phosphonates ◽  
Hypoxanthine Guanine Phosphoribosyltransferase

ABSTRACT Purine metabolism plays a ubiquitous role in the physiology of Mycobacterium tuberculosis and other mycobacteria. The purine salvage enzyme hypoxanthine-guanine phosphoribosyltransferase (HGPRT) is essential for M. tuberculosis growth in vitro; however, its precise role in M. tuberculosis physiology is unclear. Membrane-permeable prodrugs of specifically designed HGPRT inhibitors arrest the growth of M. tuberculosis and represent potential new antituberculosis compounds. Here, we investigated the purine salvage pathway in the model organism Mycobacterium smegmatis. Using genomic deletion analysis, we confirmed that HGPRT is the only guanine and hypoxanthine salvage enzyme in M. smegmatis but is not required for in vitro growth of this mycobacterium or survival under long-term stationary-phase conditions. We also found that prodrugs of M. tuberculosis HGPRT inhibitors displayed an unexpected antimicrobial activity against M. smegmatis that is independent of HGPRT. Our data point to a different mode of mechanism of action for these inhibitors than was originally proposed. IMPORTANCE Purine bases, released by the hydrolytic and phosphorolytic degradation of nucleic acids and nucleotides, can be salvaged and recycled. The hypoxanthine-guanine phosphoribosyltransferase (HGPRT), which catalyzes the formation of guanosine-5′-monophosphate from guanine and inosine-5′-monophosphate from hypoxanthine, represents a potential target for specific inhibitor development. Deletion of the HGPRT gene (Δhgprt) in the model organism Mycobacterium smegmatis confirmed that this enzyme is not essential for M. smegmatis growth. Prodrugs of acyclic nucleoside phosphonates (ANPs), originally designed against HGPRT from Mycobacterium tuberculosis, displayed anti-M. smegmatis activities comparable to those obtained for M. tuberculosis but also inhibited the Δhgprt M. smegmatis strain. These results confirmed that ANPs act in M. smegmatis by a mechanism independent of HGPRT.

scholarly journals Combination of Miconazole and Domiphen Bromide Is Fungicidal against Biofilms of Resistant Candida spp.

2020 ◽  
Vol 64 (10) ◽  
Author(s):  
Jana Tits ◽  
Freya Cools ◽  
Kaat De Cremer ◽  
Katrijn De Brucker ◽  
Judith Berman ◽  
...  
Keyword(s):  
Fungal Infections ◽  
Drug Repurposing ◽  
Vulvovaginal Candidiasis ◽  
Antibiofilm Activity ◽  
Ammonium Compound ◽  
Candida Spp ◽  
Vaginal Infections ◽  
Content Type ◽  
Development Of Resistance

ABSTRACT The occurrence and recurrence of mucosal biofilm-related Candida infections, such as oral and vulvovaginal candidiasis, are serious clinical issues. Vaginal infections caused by Candida spp., for example, affect 70 to 75% of women at least once during their lives. Miconazole (MCZ) is the preferred topical treatment against these fungal infections, yet it has only moderate antibiofilm activity. Through screening of a drug-repurposing library, we identified the quaternary ammonium compound domiphen bromide (DB) as an MCZ potentiator against Candida biofilms. DB displayed synergistic anti-Candida albicans biofilm activity with MCZ, reducing the number of viable biofilm cells 1,000-fold. In addition, the MCZ-DB combination also resulted in significant killing of biofilm cells of azole-resistant C. albicans, C. glabrata, and C. auris isolates. In vivo, the MCZ-DB combination had significantly improved activity in a vulvovaginal candidiasis rat model compared to that of single-compound treatments. Data from an artificial evolution experiment indicated that the development of resistance against the combination did not occur, highlighting the potential of MCZ-DB combination therapy to treat Candida biofilm-related infections.

scholarly journals Treatment of Infections Caused by Extended-Spectrum-Beta-Lactamase-, AmpC-, and Carbapenemase-ProducingEnterobacteriaceae

2018 ◽  
Vol 31 (2) ◽  
Author(s):  
Jesús Rodríguez-Baño ◽  
Belén Gutiérrez-Gutiérrez ◽  
Isabel Machuca ◽  
Alvaro Pascual
Keyword(s):  
Carbapenem Resistance ◽  
Multidrug Resistant ◽  
New Drugs ◽  
Beta Lactamase ◽  
Content Type ◽  
Extended Spectrum Beta Lactamase ◽  
Development Of Resistance ◽  
Extended Spectrum ◽  
Invasive Infections ◽  
Risk Patients

SUMMARYTherapy of invasive infections due to multidrug-resistantEnterobacteriaceae(MDR-E) is challenging, and some of the few active drugs are not available in many countries. For extended-spectrum β-lactamase and AmpC producers, carbapenems are the drugs of choice, but alternatives are needed because the rate of carbapenem resistance is rising. Potential active drugs include classic and newer β-lactam–β-lactamase inhibitor combinations, cephamycins, temocillin, aminoglycosides, tigecycline, fosfomycin, and, rarely, fluoroquinolones or trimethoprim-sulfamethoxazole. These drugs might be considered in some specific situations. AmpC producers are resistant to cephamycins, but cefepime is an option. In the case of carbapenemase-producingEnterobacteriaceae(CPE), only some “second-line” drugs, such as polymyxins, tigecycline, aminoglycosides, and fosfomycin, may be active; double carbapenems can also be considered in specific situations. Combination therapy is associated with better outcomes for high-risk patients, such as those in septic shock or with pneumonia. Ceftazidime-avibactam was recently approved and is active against KPC and OXA-48 producers; the available experience is scarce but promising, although development of resistance is a concern. New drugs active against some CPE isolates are in different stages of development, including meropenem-vaborbactam, imipenem-relebactam, plazomicin, cefiderocol, eravacycline, and aztreonam-avibactam. Overall, therapy of MDR-E infection must be individualized according to the susceptibility profile, type, and severity of infection and the features of the patient.

scholarly journals In Vitro Activity of Manogepix against Multidrug-Resistant and Panresistant Candida auris from the New York Outbreak

2020 ◽  
Vol 64 (11) ◽  
Author(s):  
YanChun Zhu ◽  
Shannon Kilburn ◽  
Mili Kapoor ◽  
Sudha Chaturvedi ◽  
Karen Joy Shaw ◽  
...  
Keyword(s):  
New York ◽  
Fungal Infections ◽  
Geometric Mean ◽  
Multidrug Resistant ◽  
Antifungal Drugs ◽  
New Drugs ◽  
Wild Type ◽  
Candida Auris ◽  
Content Type

ABSTRACT An ongoing Candida auris outbreak in the New York metropolitan area is the largest recorded to date in North America. Laboratory surveillance revealed NY C. auris isolates are resistant to fluconazole, with variable resistance to other currently used broad-spectrum antifungal drugs, and that several isolates are panresistant. Thus, there is an urgent need for new drugs with a novel mechanism of action to combat the resistance challenge. Manogepix (MGX) is a first-in-class agent that targets the fungal Gwt1 enzyme. The prodrug fosmanogepix is currently in phase 2 clinical development for the treatment of fungal infections. We evaluated the susceptibility of 200 New York C. auris isolates to MGX and 10 comparator drugs using CLSI methodology. MGX demonstrated lower MICs than comparators (MIC50 and MIC90, 0.03 mg/liter; range, 0.004 to 0.06 mg/liter). The local epidemiological cutoff value (ECV) for MGX indicated all C. auris isolates were within the population of wild-type (WT) strains; 0.06 mg/liter defines the upper limit of wild type (UL-WT). MGX was 8- to 32-fold more active than the echinocandins, 16- to 64-fold more active than the azoles, and 64-fold more active than amphotericin B. No differences were found in the MGX or comparators’ MIC50, MIC90, or geometric mean (GM) values when subsets of clinical, surveillance, and environmental isolates were evaluated. The range of MGX MIC values for six C. auris panresistant isolates was 0.008 to 0.015 mg/liter, and the median and mode MIC values were 0.015 mg/liter, demonstrating that MGX retains activity against these isolates. These data support further clinical evaluation of fosmanogepix for the treatment of C. auris infections, including highly resistant isolates.

scholarly journals Activity of a Long-Acting Echinocandin, Rezafungin, and Comparator Antifungal Agents Tested against Contemporary Invasive Fungal Isolates (SENTRY Program, 2016 to 2018)

2020 ◽  
Vol 64 (4) ◽  
Author(s):  
Michael A. Pfaller ◽  
Cecilia Carvalhaes ◽  
Shawn A. Messer ◽  
Paul R. Rhomberg ◽  
Mariana Castanheira
Keyword(s):  
Fungal Infections ◽  
Hot Spot ◽  
The Other ◽  
Wild Type ◽  
Fluconazole Resistance ◽  
Content Type ◽  
Fungal Isolates ◽  
Clinical Breakpoints ◽  
Long Acting

ABSTRACT We evaluated the activity of rezafungin and comparators, using Clinical and Laboratory Standards Institute (CLSI) broth microdilution methods, against a worldwide collection of 2,205 invasive fungal isolates recovered from 2016 to 2018. Candida (n = 1,904 isolates; 6 species), Cryptococcus neoformans (n = 73), Aspergillus fumigatus (n = 183), and Aspergillus flavus (n = 45) isolates were tested for their susceptibility (S) to rezafungin as well as the comparators caspofungin, anidulafungin, micafungin, and azoles. Interpretive criteria were applied following CLSI published clinical breakpoints (CBPs) and epidemiological cutoff values (ECVs). Isolates displaying non-wild-type (non-WT) echinocandin MIC values were sequenced for hot spot (HS) mutations. Rezafungin inhibited 99.8% of Candida albicans isolates (MIC50/90, 0.03/0.06 μg/ml), 95.7% of Candida glabrata isolates (MIC50/90, 0.06/0.12 μg/ml), 97.4% of Candida tropicalis isolates (MIC50/90, 0.03/0.06 μg/ml), 100.0% of Candida krusei isolates (MIC50/90, 0.03/0.06 μg/ml), and 100.0% of Candida dubliniensis isolates (MIC50/90, 0.06/0.12 μg/ml) at ≤0.12 μg/ml. All (329/329 [100.0%]) Candida parapsilosis isolates (MIC50/90,1/2 μg/ml) were inhibited by rezafungin at ≤4 μg/ml. Fluconazole resistance was detected among 8.6% of C. glabrata isolates, 12.5% of C. parapsilosis isolates, 3.2% of C. dubliniensis isolates, and 2.6% of C. tropicalis isolates. The activity of rezafungin against these 6 Candida spp. was similar to the activity of the other echinocandins. Detection of the HS mutation was performed by sequencing echinocandin-resistant or non-WT Candida isolates. Good activity against C. neoformans was observed for fluconazole and the other azoles, whereas the echinocandins, including rezafungin, displayed limited activity. Rezafungin displayed activity similar to that of the other echinocandins against A. fumigatus and A. flavus. These in vitro data contribute to accumulating research demonstrating the potential of rezafungin for preventing and treating invasive fungal infections.

scholarly journals Resistance to the antifungal activity of Aprotinin occurs through mutations in genes that function in cation homeostasis

2020 ◽  
Author(s):  
Amanda I. McColl ◽  
Rohan G.T. Lowe ◽  
James A. McKenna ◽  
Marilyn A. Anderson ◽  
Mark R. Bleackley
Keyword(s):  
Antifungal Activity ◽  
Fungal Infections ◽  
Model Organism ◽  
Full Genome Sequencing ◽  
Intracellular Magnesium ◽  
Development Of Resistance ◽  
Cation Homeostasis ◽  
Magnesium Transporter ◽  
Pancreatic Trypsin Inhibitor

AbstractAn increase in the prevalence of fungal infections is coinciding with an increase of resistance to current clinical antifungals, placing pressure on the discovery of new antifungal candidates. One option is to investigate drugs that have been approved for use for other medical conditions that have secondary antifungal activity. Aprotinin, also known as Bovine Pancreatic Trypsin inhibitor (BPTI), is an antifibrinolytic that has been approved for systemic use in patients in some countries. Bleackley and coworkers (2014) revealed that BPTI also has antifungal activity against S. cerevisiae and C. albicans and does this by targeting the magnesium transporter ALR1. Here we have further investigated the potential for aprotinin to be used as an antifungal by assessing the development of resistance. We used an in vitro model to assess the evolution of BPTI resistance/tolerance whereby BPTI was serial passaged with the model organism S. cerevisiae. Resistance to BPTI developed more quickly than resistance to the plant defensin NaD1 and the clinical antifungal, caspofungin. Full genome sequencing of resistant lines revealed that resistance to BPTI developed as the result of a deleterious mutation in either the ptk2 or sky1 genes. This revealed that cation homeostasis and transport functions were particularly affected in S. cerevisiae after exposure to BPTI. Therefore, the mutations in these genes probably decreases release of magnesium and other cations from the cell, protecting the yeast from the limiting intracellular magnesium levels that arise when BPTI blocks the magnesium transporter Alr1p.

scholarly journals Experimental Induction of Fluconazole Resistance in Candida tropicalis ATCC 750

2000 ◽  
Vol 44 (6) ◽  
pp. 1578-1584 ◽  
Author(s):  
Francesco Barchiesi ◽  
David Calabrese ◽  
Dominique Sanglard ◽  
Luigi Falconi Di Francesco ◽  
Francesca Caselli ◽  
...  
Keyword(s):  
Candida Tropicalis ◽  
Fungal Infections ◽  
Free Medium ◽  
Multidrug Efflux ◽  
Dosing Regimen ◽  
Fluconazole Resistance ◽  
Development Of Resistance ◽  
Atp Binding Cassette Transporter ◽  
Resistant Strains

ABSTRACT Candida tropicalis is less commonly isolated from clinical specimens than Candida albicans. UnlikeC. albicans, which can be occasionally found as a commensal, C. tropicalis is almost always associated with the development of fungal infections. In addition, C. tropicalis has been reported to be resistant to fluconazole (FLC). To analyze the development of FLC resistance in C. tropicalis, an FLC-susceptible strain (ATCC 750) (MIC = 1.0 μg/ml) was cultured in liquid medium containing increasing FLC concentrations from 8.0 to 128 μg/ml. The strain developed variable degrees of FLC resistance which paralleled the concentrations of FLC used in the medium. The highest MICs of FLC were 16, 256, and 512 μg/ml for strains grown in medium with 8.0, 32, and 128 μg of FLC per ml, respectively. Development of resistance was rapid and could be observed already after a single subculture in azole-containing medium. The resistant strains were cross-resistant to itraconazole (MIC > 1.0 μg/ml) and terbinafine (MIC > 512 μg/ml) but not to amphotericin B. Isolates grown in FLC at concentrations of 8.0 and 32 μg/ml reverted to low MICs (1.0 μg/ml) after 12 and 11 passages in FLC-free medium, respectively. The MIC for one isolate grown in FLC (128 μg/ml) (128 R) reverted to 16 μg/ml but remained stable over 60 passages in FLC-free medium. Azole-resistant isolates revealed upregulation of two different multidrug efflux transporter genes: the major facilitators gene MDR1 and the ATP-binding cassette transporter CDR1. The development of FLC resistance in vitro correlated well with the results obtained in an experimental model of disseminated candidiasis. While FLC given at 10 mg/kg of body weight/day was effective in reducing the fungal burden of mice infected with the parent strain, the same dosing regimen was ineffective in mice infected with strain 128 R. Finally, the acquisition of in vitro FLC resistance in strain 128 R was related to a loss of virulence. The results of our study elucidate important characteristics and potential mechanisms of FLC resistance in C. tropicalis.

Cdr2p contributes to fluconazole resistance in Candida dubliniensis clinical isolates

2011 ◽  
Vol 57 (5) ◽  
pp. 416-426 ◽  
Author(s):  
Silvia Borecká ◽  
Emmanuelle Pinjon ◽  
Derek J. Sullivan ◽  
Karl Kuchler ◽  
Jaroslav Blaško ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Fungal Infections ◽  
Medical Problem ◽  
Sterol Composition ◽  
Candida Dubliniensis ◽  
Clinical Isolates ◽  
Fluconazole Resistance ◽  
Development Of Resistance ◽  
Growth Phenomenon ◽  
Fluconazole Resistant

The development of resistance to azole antifungals used in the treatment of fungal infections can be a serious medical problem. Here, we investigate the molecular mechanisms associated with reduced susceptibility to fluconazole in clinical isolates of Candida dubliniensis , showing evidence of the trailing growth phenomenon. The changes in membrane sterol composition were studied in the presence of subinhibitory fluconazole concentrations. Despite lanosterol and eburicol accumulating as the most prevalent sterols after fluconazole treatment, these ergosterol precursors still support growth of Candida isolates. The overexpression of ABC transporters was demonstrated by immunoblotting employing specific antibodies against Cdr1p and Cdr2p. The presence of a full-length 170 kDa protein Cdr1p was detected in two isolates, while a truncated form of Cdr1p with the molecular mass of 85 kDa was observed in isolate 966/3(2). Notably, Cdr2p was detected in this isolate, and the expression of this transporter was modulated by subinhibitory concentrations of fluconazole. These results suggest that C. dubliniensis can display the trailing growth phenomenon, and such isolates express similar molecular mechanisms like that of fluconazole-resistant isolates and can therefore be associated with recurrent infections.

The antifungal activities and biological consequences of BMVC-12C-P, a carbazole derivative against Candida species

2019 ◽  
Vol 58 (4) ◽  
pp. 521-529
Author(s):  
Mandy Shen ◽  
Pei-Tzu Li ◽  
Yan-Jia Wu ◽  
Ching-Hsuan Lin ◽  
Eric Chai ◽  
...  
Keyword(s):  
Candida Species ◽  
Fungal Infections ◽  
Antifungal Drugs ◽  
New Drugs ◽  
High Morbidity ◽  
Carbazole Derivative ◽  
Antifungal Activities ◽  
Development Of Resistance ◽  
Fluconazole Resistant ◽  
Candida Infections

Abstract Fungal infections, particularly Candida species, have increased worldwide and caused high morbidity and mortality rates. The toxicity and development of resistance in present antifungal drugs justify the need of new drugs with different mechanism of action. BMVC-12C-P, a carbazole-type compound, has been found to dysfunction mitochondria. BMVC-12C-P displayed the strongest antifungal activities among all of the BMVC derivatives. The minimal inhibitory concentration (MIC) of BMVC-12C-P against Candida species ranged from 1 to 2 μg/ml. Fluconazole-resistant clinical isolates of Candida species were highly susceptible to BMVC-12C-P. The potent fungicidal activity of BMVC-12C-P relates to its impairing mitochondrial function. Furthermore, we found that the hyphae growth and biofilm formation were suppressed in C. albicans survived from BMVC-12C-P treatment. This study demonstrates the potential of BMVC-12C-P as an antifungal agent for treating Candida infections.

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