Azole Antifungal Resistance in Candida albicans and Emerging Non-albicans Candida Species

Genetic Manipulation as a Tool to Unravel Candida parapsilosis Species Complex Virulence and Drug Resistance: State of the Art

An increase in the rate of isolation of Candida parapsilosis in the past decade, as well as increased identification of azole-resistant strains are concerning, and require better understanding of virulence-like factors and drug-resistant traits of these species. In this regard, the present review “draws a line” on the information acquired, thus far, on virulence determinants and molecular mechanisms of antifungal resistance in these opportunistic pathogens, mainly derived from genetic manipulation studies. This will provide better focus on where we stand in our understanding of the C. parapsilosis species complex–host interaction, and how far we are from defining potential novel targets or therapeutic strategies—key factors to pave the way for a more tailored management of fungal infections caused by these fungal pathogens.

PDR Transporter ABC1 Is Involved in the Innate Azole Resistance of the Human Fungal Pathogen Fusarium keratoplasticum

Fusarium keratoplasticum is arguably the most common Fusarium solani species complex (FSSC) species associated with human infections. Invasive fusariosis is a life-threatening fungal infection that is difficult to treat with conventional azole antifungals. Azole drug resistance is often caused by the increased expression of pleiotropic drug resistance (PDR) ATP-binding cassette (ABC) transporters of the ABCG sub-family. Most investigations of Fusarium ABC transporters associated with azole antifungal drug resistance are limited to plant pathogens. Through the manual curation of the entire ABCG protein family of four FSSC species including the fully annotated genome of the plant pathogen Nectria haematococca we identified PDR transporters ABC1 and ABC2 as the efflux pump candidates most likely to be associated with the innate azole resistance phenotype of Fusarium keratoplasticum. An initial investigation of the transcriptional response of logarithmic phase F. keratoplasticum cells to 16 mg/L voriconazole confirmed strong upregulation (372-fold) of ABC1 while ABC2 mRNA levels were unaffected by voriconazole exposure over a 4 h time-period. Overexpression of F. keratoplasticum ABC1 and ABC2 in the genetically modified Saccharomyces cerevisiae host ADΔΔ caused up to ∼1,024-fold increased resistance to a number of xenobiotics, including azole antifungals. Although ABC1 and ABC2 were only moderately (20% and 10%, respectively) expressed compared to the Candida albicans multidrug efflux pump CDR1, overexpression of F. keratoplasticum ABC1 caused even higher resistance levels to certain xenobiotics (e.g., rhodamine 6G and nigericin) than CDR1. Our investigations suggest an important role for ABC1 orthologues in the innate azole resistance phenotype of FSSC species.

Photodynamic activity of Tagetes minuta extracts against superficial fungal infections

Candida and dermatophyte species are the most common causes of superficial mycoses because their treatment can be difficult due to limitations of current antifungal drugs in terms of toxicity, bioavailability, interactions, narrow-spectrum activity, and development of resistance. Photodynamic therapy (PDT) involves the topical administration of a photosensitizer in combination with light of an appropriate wavelength and molecular oxygen that produces reactive oxygen species (ROS), which promote damage to several vital components of the microorganism. Tagetes species are known as a source of thiophenes, biologically active compounds whose antifungal activity is enhanced by irradiation with UVA. The present investigation evaluated Tagetes minuta extracts as a photosensitizer on growth of Candida and dermatophytes and their effect on Candida virulence factors. T. minuta root hexane and dichloromethane extracts demonstrated high photodynamic antifungal activity. Bioautographic assays and chromatographic analysis revealed the presence of five thiophenes with reported photodynamic antifungal activities under UVA. Analysis of ROS production indicated that both type I and II reactions were involved in the activity of the extracts. In addition, the extracts inhibited virulence factors of Candida, such as adherence to epithelial surfaces and germ tube formation and showed efficacy against different Candida morphologies: budding cells, cells with germ tube and biofilms. Results suggested that PDT with T. minuta extracts might become a valuable alternative to the already established antifungal drugs for the treatment of superficial fungal infections.

Antifungal susceptibility, genotyping, resistance mechanism, and clinical profile of Candida tropicalis blood isolates

Candida tropicalis is one of the major candidaemia agents, associated with the highest mortality rates among Candida species, and developing resistance to azoles. Little is known about the molecular mechanisms of azole resistance, genotypic diversity, and the clinical background of C. tropicalis infections. Consequently, this study was designed to address those questions. Sixty-four C. tropicalis bloodstream isolates from 62 patients from three cities in Iran (2014–2019) were analyzed. Strain identification, antifungal susceptibility testing, and genotypic diversity analysis were performed by MALDI-TOF MS, CLSI-M27 A3/S4 protocol, and amplified fragment length polymorphism (AFLP) fingerprinting, respectively. Genes related to drug resistance (ERG11, MRR1, TAC1, UPC2, and FKS1 hotspot9s) were sequenced. The overall mortality rate was 59.6% (37/62). Strains were resistant to micafungin [minimum inhibitory concentration (MIC) ≥1 μg/ml, 2/64], itraconazole (MIC > 0.5 μg/ml, 2/64), fluconazole (FLZ; MIC ≥ 8 μg/ml, 4/64), and voriconazole (MIC ≥ 1 μg/ml, 7/64). Pan-azole and FLZ + VRZ resistance were observed in one and two isolates, respectively, while none of the patients were exposed to azoles. MRR1 (T255P, 647S), TAC1 (N164I, R47Q), and UPC2 (T241A, Q340H, T381S) mutations were exclusively identified in FLZ-resistant isolates. AFLP fingerprinting revealed five major and seven minor genotypes; genotype G4 was predominant in all centers. The increasing number of FLZ-R C. tropicalis blood isolates and acquiring FLZ-R in FLZ-naive patients limit the efficiency of FLZ, especially in developing countries. The high mortality rate warrants reaching a consensus regarding the nosocomial mode of C. tropicalis transmission.

Targeted amplification and MinION nanopore sequencing of key azole and echinocandin resistance determinants of clinically relevant Candida spp. from blood culture bottles

The objective of the study was to evaluate the use of targeted multiplex Nanopore MinION amplicon re-sequencing of key Candida spp. from blood culture bottles to identify azole and echinocandin resistance associated SNPs. Targeted PCR amplification of azole (ERG11 and ERG3) and echinocandin (FKS) resistance-associated loci was performed on positive blood culture media. Sequencing was performed using MinION nanopore device with R9.4.1 Flow Cells. Twenty-eight spiked blood cultures (ATCC strains and clinical isolates) and 12 prospectively collected positive blood cultures with candidaemia were included. Isolate species included Candida albicans, Candida glabrata, Candida krusei, Candida parapsilosis, Candida tropicalis and Candida auris. SNPs that were identified on ERG and FKS genes using Snippy tool and CLC Genomic Workbench were correlated with phenotypic testing by broth microdilution (YeastOne™ Sensititre). Illumina whole-genome-sequencing and Sanger-sequencing were also performed as confirmatory testing of the mutations identified from nanopore sequencing data. There was a perfect agreement of the resistance-associated mutations detected by MinION-nanopore-sequencing compared to phenotypic testing for acquired resistance (16 with azole resistance; 3 with echinocandin resistance), and perfect concordance of the nanopore sequence mutations to Illumina and Sanger data. Mutations with no known association with phenotypic drug resistance and novel mutations were also detected.

Investigational Agents for the Treatment of Resistant Yeasts and Molds

Purpose of Review

This review summarizes the investigational antifungals in clinical development with the potential to address rising drug resistance patterns. The relevant pharmacodynamics, spectrum of activity, preclinical studies, and latest clinical trial data are described.

Recent Findings

Agricultural and medicinal antifungal use has been selected for inherently drug-resistant fungi and acquired resistance mechanisms. The rates of fungal infections and immunocompromised populations continue to grow as few new antifungals have hit the market. Several agents with the potential to address the emergence of multidrug-resistant (MDR) molds and yeasts are in clinical development.

Summary

Evolved formulations of echinocandins, polyenes, and triazoles offer less toxicity, convenient dosing, and greater potency, potentially expanding these classes’ indications. Ibrexafungerp, olorofim, oteseconazole, and fosmanogepix possess novel mechanisms of actions with potent activity against MDR fungi. Successful clinical development is neither easy nor guaranteed; thus, perpetual efforts to discover new antifungals are needed.

Cell Wall Proteome Profiling of a Candida albicans Fluconazole-Resistant Strain from a Lebanese Hospital Patient Using Tandem Mass Spectrometry-A Pilot Study

Candida albicans is an opportunistic pathogenic fungus responsible for high mortality rates in immunocompromised individuals. Azole drugs such as fluconazole are the first line of therapy in fungal infection treatment. However, resistance to azole treatment is on the rise. Here, we employ a tandem mass spectrometry approach coupled with a bioinformatics approach to identify cell wall proteins present in a fluconazole-resistant hospital isolate upon drug exposure. The isolate was previously shown to have an increase in cell membrane ergosterol and cell wall chitin, alongside an increase in adhesion, but slightly attenuated in virulence. We identified 50 cell wall proteins involved in ergosterol biosynthesis such as Erg11, and Erg6, efflux pumps such as Mdr1 and Cdr1, adhesion proteins such as Als1, and Pga60, chitin deposition such as Cht4, and Crh11, and virulence related genes including Sap5 and Lip9. Candidial proteins identified in this study go a long way in explaining the observed phenotypes. Our pilot study opens the way for a future large-scale analysis to identify novel proteins involved in drug-resistance mechanisms.

Internalization and membrane activity of the antimicrobial peptide CGA-N12

Antimicrobial peptides (AMPs) are conventional antibiotic alternatives due to their broad-spectrum antimicrobial activities and special mechanisms of action against pathogens. The antifungal peptide CGA-N12 was originally derived from human chromogranin A (CGA) and consists of the 65th to 76th amino acids of the CGA N-terminal region. In the present study, we found that CGA-N12 had fungicidal activity and exhibited time-dependent inhibition activity against Candida tropicalis. CGA-N12 entered the cells to exert its antagonist activity. The internalization of CGA-N12 was energy-dependent and accompanied by actin cytoskeleton-, clathrin-, sulfate proteoglycan-, endosome-, and lipid-depleting agent-mediated endocytosis. Moreover, the CGA-N12 internalization pathway was related to the peptide concentration. The effects of CGA-N12 on the cell membrane were investigated. CGA-N12 at a low concentration less than 4 × MIC100 did not destroy the cell membrane. While with increasing concentration, the damage to the cell membrane caused by CGA-N12 became more serious. At concentrations greater than 4 × MIC100, CGA-N12 destroyed the cell membrane integrity. Therefore, the membrane activity of CGA-N12 is concentration dependant.

Yeast Cells in Microencapsulation. General Features and Controlling Factors of the Encapsulation Process

Besides their best-known uses in the food and fermentation industry, yeasts have also found application as microcapsules. In the encapsulation process, exogenous and most typically hydrophobic compounds diffuse and end up being passively entrapped in the cell body, and can be released upon application of appropriate stimuli. Yeast cells can be employed either living or dead, intact, permeabilized, or even emptied of all their original cytoplasmic contents. The main selling points of this set of encapsulation technologies, which to date has predominantly targeted food and-to a lesser extent-pharmaceutical applications, are the low cost, biodegradability and biocompatibility of the capsules, coupled to their sustainable origin (e.g., spent yeast from brewing). This review aims to provide a broad overview of the different kinds of yeast-based microcapsules and of the main physico-chemical characteristics that control the encapsulation process and its efficiency.

Application of probiotics in candidiasis management

Candidiasis (e.g., oral, gastrointestinal, vaginal, urinary tract, systemic) is a worldwide growing problem, since antifungal resistance and immunosuppression states are rising. To address this problem, very few drugs are available for the treatment of Candida spp. infections. Therefore, novel therapeutic strategies are urgently required. Probiotics have been proposed for the prevention and treatment of bacterial infections due to their safety record and efficacy, however, little is still known about their potential role regarding fungal infections. The purpose of this review is to present an updated summary of the evidence of the antifungal effects of probiotics along with a discussion of their potential use as an alternative/complementary therapy against Candida spp. infections. Thus, we performed a literature search using appropriate keywords ("Probiotic + Candida", "Candidiasis treatment", and "Probiotic + candidiasis") to retrieve relevant studies (both preclinical and clinical) with special emphasis on the works published in the last 5 years. An increasing amount of evidence has shown the potential usefulness of probiotics in the management of oral and vulvovaginal candidiasis in recent years. Among other results, we found that, as for bacterial infections, Lactobacillus, Bifidobacterium, and Saccharomyces are the most studied and effective genus for this purpose. However, in other areas, particularly in skincandidiaisis, studies are low or lacking. Thus, further investigation is necessary including in vitro and in vivo studies to establish the usefulness of probiotics in the management of candidiasis.

Mechanism of the lethal effect of Riparin E against bacterial and yeast strains

Riparins are alkamides naturally found in the fruits of Aniba riparia (Nees) Mez, but currently synthetic molecules as Riparin E (Rip-E) can be obtained. Potential biological of Rip-E as schistosomicidal agent against Schistosoma mansoni worms, as well as against Staphylococcus aureus strains has already been described. However, the mechanism of action related to antimicrobial activity of Rip-E against bacterial or fungi species has not yet been reported. This study had as objective to evaluate the Rip-E antimicrobial activity against Gram-positive and Gram-negative bacteria, as well as against yeast species of clinical importance. Minimal inhibitory concentrations of the compound against bacterial and yeast strains were determined by microdilution method. To verify if a possible lethal effect caused by Rip-E were related to plasma membrane damage, microbial cells treated with Rip-E were stained with 7-aminoactinomycin D (7-AAD) and analyzed by flow cytometry. Rip-E showed a bactericide effect against Gram-positive species S. aureus and S. epidermidis, as well as, against Gram-negative species Escherichia coli and Salmonella enterica Typhimurium, but was inactive against Pseudomonas aeruginosa. Moreover, Rip-E showed activity against fungi species Candida albicans and C. tropicalis. S. aureus, E. coli and C. albicans cells treated with Rip-E were marked with 7-aminoactinomycin D (7-AAD) indicating that Rip-E can cause plasma membrane damage, acting as a potential microbicide agent for prevention or treatment of infectious diseases.

Design and Synthesis of New Antifungals Based on N-Un-substituted Azoles as 14α Demethylase Inhibitor

OBJECTIVE

Azole antifungal agents, which are widely used as antifungal antibiotics, inhibit cytochrome P450 sterol 14α-demethylase (CYP51). Nearly all azole antifungal agents are Nsubstituted azoles. In addition, an azolylphenalkyl pharmacophore is uniquely shared by all azole antifungals. Due to the importance of nitrogen atom of azoles (N-3 of imidazole and N-4 of triazole) in coordination with heme in the binding site of the enzyme, here a group of N- un-substituted azoles in which both nitrogen are un-substituted was reported.

MATERIALS AND METHODS

Designed compounds were synthesized by the reaction of imidazole-4- carboxaldehyde with appropriate arylamines and subsequently reduced to desired amine derivatives. Antifungal activity against Candida albicans and Saccharomyces cervisiae was done using a broth micro-dilution assay. Docking studies were done using AutoDock.

RESULTS

Antimicrobial evaluation revealed that some of these compounds exhibited moderate antimicrobial activities against tested pathogenic fungi, wherein compounds 3, 7, and 8 were potent. Docking studies propose that all of the prepared azoles interacted with 14α-DM, wherein azoleheme coordination played the main role in drug-receptor interaction.

CONCLUSION

Our results offer some useful references for molecular design performance or modification of this series of compounds as a lead compound to discover new and potent antimicrobial agents.

Assessing the Bioactive Profile of Antifungal-Loaded Calcium Sulfate against Fungal Biofilms

Calcium sulfate (CS) has been used clinically as a bone- or void-filling biomaterial, and its resorptive properties have provided the prospect for its use as a release mechanism for local antibiotics to control biofilms. Here, we aimed to test CS beads loaded with three antifungal drugs against planktonic and sessile fungal species to assess whether these antifungal beads could be harnessed to provide consistent release of antifungals at biofilm-inhibitory doses. A panel of different fungal species (n = 15) were selected for planktonic broth microdilution testing with fluconazole (FLZ), amphotericin B (AMB), and caspofungin (CSP). After establishing planktonic inhibition, antifungal CS beads were introduced to fungal biofilms (n = 5) to assess biofilm formation and cell viability through a combination of standard quantitative and qualitative biofilm assays. Inoculation of a hydrogel substrate, packed with antifungal CS beads, was also used to assess diffusion through a semidry material, to mimic active infection in vivo In general, antifungals released from loaded CS beads were all effective at inhibiting the pathogenic fungi over 7 days within standard MIC ranges for these fungi. We observed a significant reduction of pregrown fungal biofilms across key fungal pathogens following treatment, with visually observable changes in cell morphology and biofilm coverage provided by scanning electron microscopy. Assessment of biofilm inhibition also revealed reductions in total and viable cells across all organisms tested. These data show that antifungal-loaded CS beads produce a sustained antimicrobial effect that inhibits and kills clinically relevant fungal species in vitro as planktonic and biofilm cells.

Effects of Antifungal Carriers Based on Chitosan-Coated Iron Oxide Nanoparticles on Microcosm Biofilms

Resistance of Candida species to conventional therapies has motivated the development of antifungal nanocarriers based on iron oxide nanoparticles (IONPs) coated with chitosan (CS). This study evaluates the effects of IONPs-CS as carriers of miconazole (MCZ) or fluconazole (FLZ) on microcosm biofilms. Pooled saliva from two healthy volunteers supplemented with C. albicans and C. glabrata was the inoculum for biofilm formation. Biofilms were formed for 96 h on coverslips using the Amsterdam Active Attachment model, followed by 24 h treatment with nanocarriers containing different concentrations of each antifungal (78 and 156 µg/mL). MCZ or FLZ (156 µg/mL), and untreated biofilms were considered as controls. Anti-biofilm effects were evaluated by enumeration of colony-forming units (CFUs), composition of the extracellular matrix, lactic acid production, and structure and live/dead biofilm cells (confocal laser scanning microscopy-CLSM). Data were analyzed by one-way ANOVA and Fisher LSD's test (α = 0.05). IONPs-CS carrying MCZ or FLZ were the most effective treatments in reducing CFUs compared to either an antifungal agent alone for C. albicans and MCZ for C. glabrata. Significant reductions in mutans streptococci and Lactobacillus spp. were shown, though mainly for the MCZ nanocarrier. Antifungals and their nanocarriers also showed significantly higher proportions of dead cells compared to untreated biofilm by CLSM (p < 0.001), and promoted significant reductions in lactic acid, while simultaneously showing increases in some components of the extracellular matrix. These findings reinforce the use of nanocarriers as effective alternatives to fight oral fungal infections.

Naringin-generated ROS promotes mitochondria-mediated apoptosis in Candida albicans

Naringin is a flavonoid which has a therapeutic effect. However, the details of its antifungal mechanism have not yet been fully elucidated. This study focused on clarifying the relationship between naringin and Candida albicans, to understand its mode of antifungal action. In general, naringin is an antioxidant, but our results indicated that 1 mM naringin generates intracellular superoxide (O₂ ^- ) and hydroxyl radicals (OH^- ). Reactive oxygen species (ROS) have a serious impact on Ca²⁺ signaling and the production of mitochondrial ROS. After exposure to enhanced O₂ ^- and OH^- , mitochondrial Ca²⁺ overload and mitochondrial O₂ ^- generation were confirmed in C. albicans. It was verified that mitochondrial O₂ ^- transforms mitochondrial glutathione (GSH) to oxidized GSH (GSSG), leading to extreme oxidative stress in mitochondria. The previously observed Ca²⁺ accumulation and oxidative stress resulted in mitochondrial membrane potential (MMP) alteration and increased mitochondrial mass. In succession, cytochrome c release from the mitochondria to the cytosol was detected due to MMP loss. Cytochrome c promotes the initiation of apoptosis, and further experiments were performed to assess the apoptotic hallmarks. Metacaspases activation, chromosomal condensation, DNA fragmentation, and phosphatidylserine exposure were observed, indicating that naringin induces apoptosis in C. albicans. In conclusion, our findings manifested that naringin-generated O₂ ^- and OH^- damage the mitochondria and that mitochondrial dysfunction-mediated apoptosis is novel antifungal mechanism of naringin.

Species distribution, azole resistance and related molecular mechanisms in invasive Candida parapsilosis complex isolates: Increase in fluconazole resistance in 21 years

BACKGROUND

Candida parapsilosis complex consists of three species, the prevalence and geographical distribution of which might vary. Increasing rates of fluconazole resistance among C. parapsilosis complex were reported from various centres.

OBJECTIVES

Aim of this study was to identify invasive C. parapsilosis complex strains up to species level, explore rates and molecular mechanisms of azole resistance and analyse temporal changes at a single centre.

METHODS

Isolates from blood cultures from 1997 to 2017 were included. Species were identified using RFLP of the SADH gene and confirmed with ITS sequencing when needed. In vitro susceptibility to fluconazole, voriconazole and posaconazole was tested and evaluated using EUCAST guidelines. Sequences of ERG11 and MRR1 genes were analysed for fluconazole non-susceptible isolates.

RESULTS

A total of 283 isolates from 181 patients were tested for azole susceptibility. All were C. parapsilosis sensu stricto, except one C. orthopsilosis. All three azoles were effective against 213 of the isolates from 135 patients, including one C. orthopsilosis. Fluconazole resistance was 13.3% (24/181 patients). While the first fluconazole-resistant isolates were detected in 2004, increase was evident after 2011. In ERG11, Y132F mutation was the most common among fluconazole non-susceptible isolates (71.7%), followed by G458S (10.9%) and D421N (4.3%). In MRR1, R405K (56.5%) and G927C (8.7%) were detected. However, association of these mutations to azole resistance is yet to be investigated.

CONCLUSIONS

Rising azole resistance rates in C. parapsilosis sensu stricto isolates particularly after 2011 were of concern. The well-known Y132F mutation was the predominant mechanism of azole resistance while accompanied with other genetic mutations.

Association of oral candidal species with human immunodeficiency virus patients of West Godavari district, Andhra Pradesh - An in vitro study

Introduction:

Human immunodeficiency virus (HIV) infection is a major worldwide health problem characterized by progressive immunosuppression. The morbidity of HIV patients is due to its association with opportunistic infections among which oral candidiasis is common. Regardless of HIV status, candidiasis can prevail when their immune system is depressed. Oral candidiasis can thus serve as a useful marker for both restoration of immune functions and HIV disease progression. Routine identification of Candida species is laborious and time-consuming. HICHROM agar stains different species into different colors facilitating rapid reliable identification of candida species as they differ in their virulence and sensitivity to antifungal drugs.

Materials and Methods:

This cross-sectional study includes a total of 200 HIV seropositive patients from Anti-Retroviral Therapy Centre, West Godavari District. Unstimulated saliva samples were collected in a screw-capped universal container. Five microliters of each sample using a sterile inoculating loop is streaked on the chromogenic agar culture media. The colonies formed are counted using a magnifying glass and LAPIZ colony counter. Candidal colony-forming units per milliliter were analyzed, compared and correlated among different study groups. Different candida species were also identified in the study.

Results:

Nonalbicans Candida was the most common species isolated in our study accounting for 53% and Candida albicans accounting for 47%. Considering initial and final CD4 counts, there is improvement in patients on retroviral therapy.

Conclusion:

Identification of the species is important for epidemiological reasons and for treatment purposes to ensure a better prognosis since some species present reduced susceptibility to azoles.

Genotyping, antifungal susceptibility, enzymatic activity, and phenotypic variation in Candida albicans from esophageal candidiasis

Background

Esophageal candidiasis is the most frequent form of esophagitis. The pathogenicity of Candida spp. is related to a combination of microbial factors, hydrolytic enzyme secretion and phenotypic switching. This study was designed to investigate esophageal candidiasis, antifungal activity, enzymatic activity patterns, phenotyping, and genotyping profiles of Candida albicans species.

Methods

Nine hundred thirty‐three visited patients were evaluated, and esophageal biopsies from patients were included in this study during 2019–2020. Direct smear, Gram staining, and culture on CHROMagar were performed for each sample. Isolated species were identified with conventional procedures and PCR‐RFLP. Susceptibility to antifungals was determined according to CLSI guidelines. ABC typing, phenotype switching, hemolysin, proteinase, phospholipase, and esterase activity were also determined with the appropriate protocols.

Results

Twenty‐three (2.5%) patients (mean age 55.2 years) were diagnosed with esophageal candidiasis. The species isolated were 19(82.6%) C. albicans, 3(13.1%) C. glabrata, and 1(4.3%) C. tropicalis. Genotype A (57.9%) was the predominant type in C. albicans isolates. 50% of C. albicans isolates exhibited a white phenotype. A high level of phospholipase (47.4%), hemolysin (68.4%), and proteinase activity (36.8%) was observed in the C. albicans isolates. Only three C. glabrata isolates displayed non‐wild type susceptibility to voriconazole and itraconazole.

Conclusion

This study shows that C. albicans are still the most frequent isolates from patients with esophageal candidiasis. The predominance of genotype A, the white phenotype, and strong hemolysin activity may indicate a high prevalence of pathogenicity in these isolates. Sensitivity to antifungal drugs was greatest for amphotericin and fluconazole.

p-Coumaric acid loaded into liquid crystalline systems as a novel strategy to the treatment of vulvovaginal candidiasis

Vulvovaginal candidiasis (VVC) is an extremely common type of vaginal infection, which is mainly caused by Candida albicans. However, non-albicans Candida species are frequently more resistant to conventional antifungal agents and can represent up to 30% of cases. Due to side effects and increasing antifungal resistance presented by standard therapies, phenolic compounds, such as p-coumaric acid (p-CA), have been studied as molecules from natural sources with potential antifungal activity. p-CA is a poorly water-soluble compound, thus loading it into liquid crystals (LCs) may increase its solubility and effectiveness on the vaginal mucosa. Thereby, here we propose the development of mucoadhesive liquid crystalline systems with controlled release of p-CA, for the local treatment of VVC. Developed LCs consisted of fixed oily and aqueous phases (oleic acid and cholesterol (5:1) and poloxamer dispersion 16%, respectively), changing only the surfactant phase components (triethanolamine oleate (TEA-Oleate) or triethanolamine (TEA), the latter producing TEA-Oleate molecules when mixed with oleic acid). Systems were also diluted in artificial vaginal mucus (1:1 ratio) to mimic the vaginal environment and verify possible structural changes on formulations upon exposure to the mucosa. From the characterization assays, p-CA loaded TEA-Oleate systems presented mucoadhesive profile, liquid crystalline mesophases, well-organized structures and pseudoplastic behaviour, which are desirable parameters for topical formulations. Moreover, they were able to control the release of p-CA throughout the 12 h assay, as well as decrease its permeation into the vaginal mucosa. p-CA showed antifungal activity in vitro against reference strains of C. albicans (SC5314), C. glabrata (ATCC 2001) and C. krusei (ATCC 6258), and exhibited higher eradication of mature biofilms than amphotericin B and fluconazole. In vivo experiments demonstrated that the formulations reduced the presence of filamentous forms in the vaginal lavages and provided an improvement in swelling and redness present in the mice vaginal regions. Altogether, here we demonstrated the potential and feasibility of using p-CA loaded liquid crystalline systems as a mucoadhesive drug delivery system for topical treatment of VVC.

Investigation of Antifungal Properties of Synthetic Dimethyl-4-Bromo-1-(Substituted Benzoyl) Pyrrolo[1,2-a] Quinoline-2,3-Dicarboxylates Analogues: Molecular Docking Studies and Conceptual DFT-Based Chemical Reactivity Descriptors and Pharmacokinetics Evaluation

Candida albicans, an opportunistic fungal pathogen, frequently colonizes immune-compromised patients and causes mild to severe systemic reactions. Only few antifungal drugs are currently in use for therapeutic treatment. However, evolution of a drug-resistant C. albicans fungal pathogen is of major concern in the treatment of patients, hence the clinical need for novel drug design and development. In this study, in vitro screening of novel putative pyrrolo[1,2-a]quinoline derivatives as the lead drug targets and in silico prediction of the binding potential of these lead molecules against C. albicans pathogenic proteins, such as secreted aspartic protease 3 (SAP3; 2H6T), surface protein β-glucanase (3N9K) and sterol 14-alpha demethylase (5TZ1), were carried out by molecular docking analyses. Further, biological activity-based QSAR and theoretical pharmacokinetic analysis were analyzed. Here, in vitro screening of novel analogue derivatives as drug targets against C. albicans showed inhibitory potential in the concentration of 0.4 µg for BQ-06, 07 and 08, 0.8 µg for BQ-01, 03, and 05, 1.6 µg for BQ-04 and 12.5 µg for BQ-02 in comparison to the standard antifungal drug fluconazole in the concentration of 30 µg. Further, in silico analysis of BQ-01, 03, 05 and 07 analogues docked on chimeric 2H6T, 3N9K and 5TZ1 revealed that these analogues show potential binding affinity, which is different from the therapeutic antifungal drug fluconazole. In addition, these molecules possess good drug-like properties based on the determination of conceptual Density Functional Theory (DFT)-based descriptors, QSAR and pharmacokinetics. Thus, the study offers significant insight into employing pyrrolo[1,2-a]quinoline analogues as novel antifungal agents against C. albicans that warrants further investigation.

ROS-generating rare-earth coordination networks for photodynamic inactivation of Candida albicans

Water-ethanol suspensions of 2D coordination network (CN) based on rare earth elements and mixed ligands were evaluated as reactive oxygen species (ROS) generators under UV light irradiation, in contact with a biomimetic substrate (tryptophan) or an O2(1Δg) quencher (1,3-diphenylisobenzofuran; 1,3-DPBF). A combination of bottom-up and top-down strategies was implemented in order to obtain nano-sized CN particles and the subsequent colloidal suspensions were also tested towards photodynamic inactivation of Candida albicans (C. albicans). SEM, TEM, FTIR, and XRD techniques were applied to characterize the solids and ICP-AES was employed to determine the metal content of the colloidal suspensions. Promising results were found indicating that the presence of Tb3+ allows an intersystem crossing suitable for singlet oxygen generation, resulting in the antifungal activity of C. albicans culture upon UV-irradiation.

Coadministration of Ginger Extract and Fluconazole Shows a Synergistic Effect in the Treatment of Drug-Resistant Vulvovaginal Candidiasis

BACKGROUND

Azoles are the most common antifungal drugs used in the treatment of vulvovaginal candidiasis (VVC). The frequency of azole-resistant Candida isolates has increased dramatically in the last two decades. Here, we assessed the antifungal activity of a combination of fluconazole (FLZ) and methanolic extract of ginger (Meth-Gin) against drug-resistant vulvovaginal candidiasis (VVC) in a murine model.

METHODS

The in vitro activity of FLZ or a combination of FLZ and Meth-Gin was determined against Candida albicans by the agar well diffusion, macrodilution, time-kill and the biofilm eradication methods. The therapeutic efficacy of the formulations was assessed by analyzing the fungal load, pro-inflammatory cytokines, percent apoptotic cells and the histological changes in the vaginal tissues of the mice. Moreover, the renal toxicity the drug formulation was evaluated by analyzing the levels of the blood urea nitrogen (BUN) and creatinine.

RESULTS

The results of in vitro study demonstrated that FLZ did not show any activity against C. albicans, whereas a combination of FLZ and Meth-Gin demonstrated greater activity as shown by the data of the zone of growth inhibition, MIC and time-kill assay. FLZ or Meth-Gin treatment could not completely cure VVC, whereas a combination of FLZ and Meth-Gin was greatly effective in the treatment of VVC. The vaginal tissue from mice of the infected control group had the highest fungal load of 155370 ± 20617 CFUs. Treatment with FLZ at a dose of 40 mg/kg reduced the fungal load to 120863 ± 10723 CFUs. Interestingly, the mice treated with a combination of FLZ (40 mg/kg) and Meth-Gin (200 mg/kg) had a fungal load of 256 ± 152 CFUs. Besides, FLZ and Meth-Gin combination effectively reduced the pro-inflammatory cytokines (IL-1β, TNF-α and IL-17) and the percentage of apoptotic cells in the vaginal tissues. Likewise, the histological analysis revealed the epithelial necrosis, shedding and ulceration in the vaginal tissue, whereas treatment with FLZ and Meth-Gin combination reversed the histopathological changes in the vaginal epithelium and lamina propria.

CONCLUSION

The findings of the current study suggest that the co-administration of Meth-Gin and FLZ may have a potential therapeutic effect in the treatment of azole-resistant candidiasis.

Novel ERG11 and TAC1b mutations associated with azole resistance in Candida auris

Candida auris is a novel Candida species that has spread in all continents causing nosocomial outbreaks of invasive candidiasis. C. auris has the ability to develop resistance to all antifungal drug classes. Notably, many C. auris isolates are resistant to the azole drug fluconazole, a standard therapy of invasive candidiasis.Azole resistance in C. auris can result from mutations in the azole target gene ERG11 and/or overexpression of the efflux pump Cdr1. TAC1 is a transcription factor controlling CDR1 expression in C. albicans The role of TAC1 homologs in C. auris (TAC1a and TAC1b) remains to be better defined.In this study, we compared sequences of ERG11, TAC1a and TAC1b between a fluconazole-susceptible and five fluconazole-resistant C. auris isolates of clade IV. Among four of the resistant isolates, we identified a similar genotype with concomitant mutations in ERG11 (F444L) and TAC1b (S611P). The simultaneous deletion of tandemly arranged TAC1a/TAC1b resulted in a decrease of minimal inhibitory concentration (MIC) for fluconazole. Introduction of the ERG11 and TAC1b mutations separately and/or combined in the wild-type azole susceptible isolate resulted in a significant increase of azole resistance with a cumulative effect of the two combined mutations. Interestingly, CDR1 expression was not significantly affected by TAC1a/TAC1b deletion or by the presence of the TAC1b S611P mutation, suggesting the existence of Tac1-dependent and Cdr1-independent azole resistance mechanisms.We demonstrated the role of two previously unreported mutations responsible for azole resistance in C. auris, which were a common signature among four azole-resistant isolates of clade IV.

Clotrimazole-loaded N-(2-hydroxy)-propyl-3-trimethylammonium, O-palmitoyl chitosan nanoparticles for topical treatment of vulvovaginal candidiasis

Vulvovaginal candidiasis (VVC) represents a considerable health burden for women. Despite the availability of a significant array of antifungal drugs and topical products, the management of the infection is not always effective, and new approaches are needed. Here, we explored cationic N-(2-hydroxy)-propyl-3-trimethylammonium, O-palmitoyl chitosan nanoparticles (NPs) as carriers of clotrimazole (CLT) for the topical treatment of VVC. CLT-NPs with approximately 280 nm in diameter were obtained by self-assembly in water and subsequent stabilization by ionic crosslinking with tripolyphosphate. The nanosystem featured pH-independent sustained drug release up to 24 h, which affected both in vitro anti-Candida activity and cytotoxicity. The CLT-loaded nanostructured platform yielded favorable selectivity index values for a panel of standard strains and clinical isolates of Candida spp. and female genital tract cell lines (HEC-1-A, Ca Ski and HeLa), as compared to the free drug. CLT-NPs also improved in vitro drug permeability across HEC-1-A and Ca Ski cell monolayers, thus suggesting that the nanocarrier may provide higher mucosal tissue levels of the active compound. Overall, data support that CLT-NPs may be a valuable asset for the topical treatment of VVC. STATEMENT OF SIGNIFICANCE: Topical azoles such as clotrimazole (CLT) are first line antifungal drugs for the management of vulvovaginal candidiasis (VVC), but their action may be limited by issues such as toxicity and poor capacity to penetrate the genital mucosa. Herein, we report on the ability of a new cationic N-(2‑hydroxy)-propyl-3-trimethylammonium, O-dipalmitoyl chitosan derivative (DPCat35) to yield tripolyphosphate-reinforced micelle-like nanostructures that are suitable carriers for CLT. In particular, these nanosystems were able to improve the in vitro selectivity index of the drug and to provide enhanced epithelial drug permeability when tested in cell monolayer models. These data support that CLT-loaded DPCat35 nanoparticles feature favorable properties for the development of new nanomedicines for the topical management of VVC.

Effects of antifungal agents on the fungal proteome: informing on mechanisms of sensitivity and resistance

INTRODUCTION

Antifungal agents are essential in the fight against serious fungal disease, however emerging resistance is threatening an already limited collection of therapeutics. Proteomic analyses of effects of antifungal agents can expand our understanding of multifactorial mechanisms of action and have also proven valuable to elucidate proteomic changes associated with antifungal resistance.

AREAS COVERED

This review covers the application of proteomic techniques to examine sensitivity and resistance to antifungals including commonly used therapeutics, amphotericin B, echinocandins and the azoles, based predominantly on studies involving Aspergillus fumigatus, Candida albicans and Candida glabrata from the last 10 years. In addition, non-clinical antimicrobial agents are also discussed, which highlight the potential of proteomics to identify new antifungal targets.

EXPERT COMMENTARY

Fungal proteomics has evolved in the last decade with increased genome availability and developments in mass spectrometry. Collectively, these have led to the advancement of proteomic techniques, allowing increased coverage of the proteome. Gel-based proteomics laid the foundation for these types of studies, which has now shifted to the more powerful gel-free proteomics. This has resulted in the identification of key mediators and potential biomarkers of antifungal resistance, as well as elucidating the mechanisms of action of novel and established antifungal agents.

Investigation of Alternative Therapeutic and Biocidal Options to Combat Antifungal-Resistant Zoonotic Fungal Pathogens Isolated from Companion Animals

Fungal skin infections and iatrogenic disease of companion animals continue to be an ongoing issue for veterinarians, where misdiagnosis or inapt medical treatment result in secondary conditions within animals. The widespread use of antifungals in both modern medicine and agriculture has resulted in concomitant resistance in species, where zoonotic transfer poses a risk to public health. Studies described herein assess the resistance of pathogenic species isolated from companion animals to a battery of conventional antimicrobial agents. Levels of resistance were detected using recognised in vitro methods, where additional novel therapeutic and biocide options were also extensively investigated. Results show high levels of resistance to the three main families of antifungal agents, namely caspofungin, Amp B and fluconazole. Resistance in Candida, Cryptococcal, Aspergillus and Trichophyton species is described herein, highlighting the need for defined species-specific antifungal breakpoints, and for Malassezia and Wickerhamomyces anomalus species which also have zoonotic potential. Novel compound phendione showed promising antimicrobial activity, with MICs determined for both fungal and bacterial species. The biocidal options investigated also showed potential to act as intermediate-level disinfectants, where peracetic acid proved most effective against fungal spore formers.

Whole genome sequencing of a clinical drug resistant Candida albicans isolate reveals known and novel mutations in genes involved in resistance acquisition mechanisms

Candida albicans is an opportunistic pathogen accounting for the majority of cases of Candida infections. Currently, C. albicans are developing resistance towards different classes of antifungal drugs and this has become a global health burden that does not spare Lebanon. This study aims at determining point mutations in genes known to be involved in resistance acquisition and correlating resistance to virulence and ergosterol content in the azole resistant C. albicans isolate CA77 from Lebanon. This pilot study is the first of its kind to be implemented in Lebanon. We carried out whole genome sequencing of the azole resistant C. albicans isolate CA77 and examined 18 genes involved in antifungal resistance. To correlate genotype to phenotype, we evaluated the virulence potential of this isolate by injecting it into BALB/c mice and we quantified membrane ergosterol. Whole genome sequencing revealed that eight out of 18 genes involved in antifungal resistance were mutated in previously reported and novel residues. These genotypic changes were associated with an increase in ergosterol content but no discrepancy in virulence potential was observed between our isolate and the susceptible C. albicans control strain SC5314. This suggests that antifungal resistance and virulence potential in this antifungal resistant isolate are not correlated and that resistance is a result of an increase in membrane ergosterol content and the occurrence of point mutations in genes involved in the ergosterol biosynthesis pathway.

Capric acid secreted by Saccharomyces boulardii influences the susceptibility of Candida albicans to fluconazole and amphotericin B

The effect of capric acid, secreted by the probiotic yeasts Saccharomyces boulardii, was evaluated on the activities of fluconazole (FLC) and amphotericin B (AMB) against pathogenic Candida albicans fungus. The findings indicated that capric acid may be a promising additive for use in combination with FLC. A FLC-capric acid combination led to reduced efflux activity of multidrug resistance (MDR) transporter Cdr1p by causing it to relocalize from the plasma membrane (PM) to the interior of the cell. The above effect occurred due to inhibitory effect of FLC-capric acid combination of ergosterol biosynthesis. However, capric acid alone stimulated ergosterol production in C. albicans, which in turn generated cross resistance towards AMB and inhibited its action (PM permeabilization and cytoplasm leakage) against C. albicans cells. This concluded that AMB should not be administered among dietary supplements containing capric acid or S. boulardii cells.

Mechanisms of Candida Resistance to Antimycotics and Promising Ways to Overcome It: The Role of Probiotics

Pathogenic Candida and infections caused by those species are now considered as a serious threat to public health. The treatment of candidiasis is significantly complicated by the increasing resistance of pathogenic strains to current treatments and the stagnant development of new antimycotic drugs. Many species, such as Candida auris, have a wide range of resistance mechanisms. Among the currently used synthetic and semi-synthetic antifungal drugs, the most effective are azoles, echinocandins, polyenes, nucleotide analogs, and their combinations. However, the use of probiotic microorganisms and/or the compounds they produce is quite promising, although underestimated by modern pharmacology, to control the spread of pathogenic Candida species.

Fungicidal Activity of a Safe 1,3,4-Oxadiazole Derivative Against Candida albicans

Candida albicans is the most common species isolated from nosocomial bloodstream infections. Due to limited therapeutic arsenal and increase of drug resistance, there is an urgent need for new antifungals. Therefore, the antifungal activity against C. albicans and in vivo toxicity of a 1,3,4-oxadiazole compound (LMM6) was evaluated. This compound was selected by in silico approach based on chemical similarity. LMM6 was highly effective against several clinical C. albicans isolates, with minimum inhibitory concentration values ranging from 8 to 32 µg/mL. This compound also showed synergic effect with amphotericin B and caspofungin. In addition, quantitative assay showed that LMM6 exhibited a fungicidal profile and a promising anti-biofilm activity, pointing to its therapeutic potential. The evaluation of acute toxicity indicated that LMM6 is safe for preclinical trials. No mortality and no alterations in the investigated parameters were observed. In addition, no substantial alteration was found in Hippocratic screening, biochemical or hematological analyzes. LMM6 (5 mg/kg twice a day) was able to reduce both spleen and kidneys fungal burden and further, promoted the suppresses of inflammatory cytokines, resulting in infection control. These preclinical findings support future application of LMM6 as potential antifungal in the treatment of invasive candidiasis.

Multiple roles of ABC transporters in yeast

The ATP binding cassette (ABC) transporters, first discovered as high-affinity nutrient importers in bacteria, rose to prominence when their ability to confer multidrug resistance (MDR) to cancer cells was realized. The most characterized human permeability glycoprotein (P-gp) is a dominant exporter of anti-cancer drugs and its overexpression is directly linked to MDR. The overexpression of drug efflux pumps belonging to the ABC superfamily is also a frequent cause of resistance to antifungals. Fungi has a battery of ABC proteins, but in variable numbers and at different subcellular locations. These proteins perform many critical functions, from serving as gatekeepers for xenobiotic cleansing to translocating various structurally unrelated cargoes, including lipids, fatty acids, ions, peptides, sterols, metabolites and toxins. Their emerging additional roles in cellular physiology and virulence call for attention to analyze and re-examine their divergent functions in yeast. In brief, this review traces the history of ABC transporters in yeast and discusses their typical physiological functions that go beyond their well-known role as antifungal drug efflux pumps.

Antifungal Activity of 1,4-Dialkoxynaphthalen-2-Acyl Imidazolium Salts by Inducing Apoptosis of Pathogenic Candida spp

Even though Candida spp. are staying commonly on human skin, it is also an opportunistic pathogenic fungus that can cause candidiasis. The emergence of resistant Candida strains and the toxicity of antifungal agents have encouraged the development of new classes of potent antifungal agents. Novel naphthalen-2-acyl imidazolium salts (NAIMSs), especially 1,4-dialkoxy-NAIMS from 1,4-dihydroxynaphthalene, were prepared and evaluated for antifungal activity. Those derivatives showed prominent anti-Candida activity with a minimum inhibitory concentration (MIC) of 3.125 to 6.26 μg/mL in 24 h based on microdilution antifungal susceptibility test. Among the tested compounds, NAIMS 7c showed strongest antifungal activity with 3.125 μg/mL MIC value compared with miconazole which showed 12.5 μg/mL MIC value against Candida spp., and more importantly >100 μg/mL MIC value against C. auris. The production of reactive oxygen species (ROS) was increased and JC-1 staining showed the loss of mitochondrial membrane potential in C. albicans by treatment with NAIMS 7c. The increased release of ultraviolet (UV) absorbing materials suggested that NAIMS 7c could cause cell busting. The expression of apoptosis-related genes was induced in C. albicans by NAIMS 7c treatment. Taken together, the synthetic NAIMSs are of high interest as novel antifungal agents given further in vivo examination.

Diazepam's antifungal activity in fluconazole-resistant Candida spp. and biofilm inhibition in C. albicans: evaluation of the relationship with the proteins ALS3 and SAP5

The genus Candida spp. has been highlighted as one of the main etiological agents causing fungal infections, with Candida albicans being the most prominent, responsible for most cases of candidemia. Due to its capacity for invasion and tissue adhesion, it is associated with the formation of biofilms, mainly in the environment and hospital devices, decreasing the effectiveness of available treatments. The repositioning of drugs, which is characterized by the use of drugs already on the market for other purposes, together with molecular-docking methods can be used aiming at the faster development of new antifungals to combat micro-organisms. This study aimed to evaluate the antifungal effect of diazepam on mature C. albicans biofilms in vitro and its action on biofilm in formation, as well as its mechanism of action and interaction with structures related to the adhesion of C. albicans, ALS3 and SAP5. To determine the MIC, the broth microdilution test was used according to protocol M27-A3 (CLSI, 2008). In vitro biofilm formation tests were performed using 96-well plates, followed by molecular-docking protocols to analyse the binding agent interaction with ALS3 and SAP5 targets. The results indicate that diazepam has antimicrobial activity against planktonic cells of Candida spp. and C. albicans biofilms, interacting with important virulence factors related to biofilm formation (ALS3 and SAP5). In addition, treatment with diazepam triggered a series of events in C. albicans cells, such as loss of membrane integrity, mitochondrial depolarization and increased production of EROs, causing DNA damage and consequent cell apoptosis.

Anti-adherence and Anti-fungal Abilities of Thymol and Carvacrol Against Candida Species Isolated From Patients with Oral Candidiasis in Comparison with Fluconazole and Voriconazole

Background: Natural isopropyl cresols, such as thymol and carvacrol, have been known to have antifungal activities. Objectives: The current study aimed to investigate the anti-adherence and antifungal activities of thymol, carvacrol, fluconazole, and voriconazole against oral isolates of Candida albicans (C. albicans), C. glabrata, and C. krusei. Methods: The susceptibility assay for the test compounds was performed using the disk diffusion method against all Candida isolates. Also, anti-adherence activity was examined using a rapid and highly reproducible 96 well microtiter-based method. Results: Both natural phenols and antifungal drugs revealed various efficacies against studied Candida species. The susceptibility to fluconazole and voriconazole were 100% for C. albicans, 50% and 90% for C. glabrata, and 0% and 100% for C. krusei isolates, respectively. The mean diameter of the inhibition zone was greater for thymol than carvacrol in C. albicans (19.89 ± 0.80 mm versus 17.05 ± 0.61 mm), C. glabrata (18.87 ± 0.71 mm versus 15.77 ± 0.57 mm), and C. krusei (15.11 ± 0.91 mm versus 13.91 ± 1.04 mm) isolates tested. Thymol showed more effective inhibition on adherence of all Candida species than other treatments. The mean relative adherence ratios for C. albicans, C. glabrata, and C. krusei were 0.50, 0.60, and 0.64, respectively. Conclusions: This study demonstrated significant inhibitory properties of thymol and carvacrol on the adherence and growth of azole susceptible- and -resistant Candida isolates. Also, thymol was more effective for preventing the adherence of yeast cells to polystyrene in comparison to carvacrol.

Severe Candida glabrata pancolitis and fatal Aspergillus fumigatus pulmonary infection in the setting of bone marrow aplasia after CD19-directed CAR T-cell therapy - a case report

Background

Prolonged myelosuppression following CD19-directed CAR T-cell transfusion represents an important, yet underreported, adverse event. The resulting neutropenia and multifactorial immunosuppression can facilitate severe infectious complications.

Case presentation

We describe the clinical course of a 59-year-old patient with relapsed/refractory DLBCL who received Axicabtagene-Ciloleucel (Axi-cel). The patient developed ASTCT grade I CRS and grade IV ICANS, necessitating admission to the neurological ICU and prolonged application of high-dose corticosteroids and other immunosuppressive agents. Importantly, neutropenia was profound (ANC < 100/μl), G-CSF-refractory, and prolonged, lasting more than 50 days. The patient developed severe septic shock 3 weeks after CAR transfusion while receiving anti-fungal prophylaxis with micafungin. His clinical status stabilized with broad anti-infective treatment and intensive supportive measures. An autologous stem cell backup was employed on day 46 to support hematopoietic recovery. Although the counts of the patient eventually started to recover, he developed an invasive pulmonary aspergillosis, which ultimately lead to respiratory failure and death. Postmortem examination revealed signs of Candida glabrata pancolitis.

Conclusions

This case highlights the increased risk for fatal infectious complications in patients who present with profound and prolonged cytopenia after CAR T-cell therapy. We describe a rare case of C. glabrata pancolitis associated with multifactorial immunosuppression. Although our patient succumbed to a fatal fungal infection, autologous stem cell boost was able to spur hematopoiesis and may represent an important therapeutic strategy for DLBCL patients with CAR T-cell associated bone marrow aplasia who have underwent prior stem cell harvest.

Roles for Structural Biology in the Discovery of Drugs and Agrochemicals Targeting Sterol 14α-Demethylases

Antifungal drugs and antifungal agrochemicals have significant limitations. These include several unintended consequences of their use including the growing importance of intrinsic and acquired resistance. These problems underpin an increasingly urgent need to improve the existing classes of antifungals and to discover novel antifungals. Structural insights into drug targets and their complexes with both substrates and inhibitory ligands increase opportunity for the discovery of more effective antifungals. Implementation of this promise, which requires multiple skill sets, is beginning to yield candidates from discovery programs that could more quickly find their place in the clinic. This review will describe how structural biology is providing information for the improvement and discovery of inhibitors targeting the essential fungal enzyme sterol 14α-demethylase.

Exploring the druggable proteome of Candida species through comprehensive computational analysis

Candida albicans and non-albicans Candida spp. are major cause of systemic mycoses. Antifungal drugs such as azoles and polyenes are not efficient to successfully eradicate Candida infection owing to their fungistatic nature or low bioavailability. Here, we have adopted a comprehensive computational workflow for identification, prioritization and validation of targets from proteomes of Candida albicans and Candida tropicalis. The protocol involves identification of essential drug-target candidates using subtractive genomics, protein-protein interaction network properties and systems biology based methods. The essentiality of the novel metabolic and non-metabolic targets was established by performing in silico gene knockouts, under aerobic as well as anaerobic conditions, and in vitro drug inhibition assays respectively. Deletion of twelve genes that are involved in amino acid, secondary metabolite, and carbon metabolism showed zero growth in metabolic model under simulated conditions. The algorithm, used in this study, can be downloaded from http://pbit.bicnirrh.res.in/offline.php and executed locally.

Rapid detection of ERG11 polymorphism associated azole resistance in Candida tropicalis

Increasing reports of azole resistance in Candida tropicalis, highlight the development of rapid resistance detection techniques. Nonsynonymous mutations in the lanosterol C14 alpha-demethylase (ERG11) gene is one of the predominant mechanisms of azole resistance in C. tropicalis. We evaluated the tetra primer-amplification refractory mutation system-PCR (T-ARMS-PCR), restriction site mutation (RSM), and high-resolution melt (HRM) analysis methods for rapid resistance detection based on ERG11 polymorphism in C. tropicalis. Twelve azole-resistant and 19 susceptible isolates of C. tropicalis were included. DNA sequencing of the isolates was performed to check the ERG11 polymorphism status among resistant and susceptible isolates. Three approaches T-ARMS-PCR, RSM, and HRM were evaluated and validated for the rapid detection of ERG11 mutation. The fluconazole MICs for the 12 resistant and 19 susceptible isolates were 32–256 mg/L and 0.5–1 mg/L, respectively. The resistant isolates showed A339T and C461T mutations in the ERG11 gene. The T-ARMS-PCR and RSM approaches discriminated all the resistant and susceptible isolates, whereas HRM analysis differentiated all except one susceptible isolate. The sensitivity, specificity, analytical sensitivity, time, and cost of analysis suggests that these three methods can be utilized for the rapid detection of ERG11 mutations in C. tropicalis. Additionally, an excellent concordance with DNA sequencing was noted for all three methods. The rapid, sensitive, and inexpensive T-ARMS-PCR, RSM, and HRM approaches are suitable for the detection of azole resistance based on ERG11 polymorphism in C. tropicalis and can be implemented in clinical setups for batter patient management.

Mangiferin enhances the antifungal activities of caspofungin by destroying polyamine accumulation

The incidence of fungal infections has increased continuously in recent years. Caspofungin (CAS) is one of the first-line drugs for the treatment of systemic fungal infection. However, the emerging CAS-resistant clinical isolates and high economic cost for CAS administration hamper the wide application of this drug. Thus, the combined administration of CAS with other compounds that can enhance the antifungal activity and reduce the dose of CAS has gained more and more attention. In this study, we investigated the effect of mangiferin (MG) on the antifungal activities of CAS. Our results showed that MG acted synergistically with CAS against various Candida spp., including CAS-resistant C. albicans. Moreover, MG could enhance the activity of CAS against biofilm. The in vivo synergism of MG and CAS was further confirmed in a mouse model of disseminated candidiasis. To explore the mechanisms, we found that SPE1-mediated polyamine biosynthesis pathway was involved in the fungal cell stress to caspofungin. Treatment of CAS alone could stimulate SPE1 expression and accumulation of polyamines, while combined treatment of MG and CAS inhibited SPE1 expression and destroyed polyamine accumulation, which might contribute to increased oxidative damage and cell death. These results provided a promising strategy for high efficient antifungal therapies and revealed novel mechanisms for CAS resistance.

A case series of medically managed Candida parapsilosis complex prosthetic valve endocarditis

Background

In recent years, Candida parapsilosis is recognized as a species complex and is composed of Candida parapsilosis sensu stricto, Candida orthopsilosis and Candida metapsilosis. Candida parapsilosis complex prosthetic valve endocarditis (PVE) is rare and the survival rate is still low despite of optimal therapeutic strategies. In our report, it is novel to report cases as Candida parapsilosis complex PVE at species and identify Candida parapsilosis using MALDI-TOF MS.

Case presentation

A series of 4 cases of Candida parapsilosis complex PVE from our institution was reported. Three were infected by Candida parapsilosis sensu stricto and one was infected by Candida metapsilosis. The condition of two cases got better and the other died.

Conclusions

More attention should be paid to Candida parapsilosis complex PVE and early diagnosis and prompt antibiotic therapy may play a role in the treatment for Candida parapsilosis complex PVE. It is recommended to identify Candida parapsilosis complex at species level and MALDI-TOF MS as an easy, fast and efficient identification method is worth promoting in clinical microbiology

Anti-inflammatory potential of myristic acid and palmitic acid synergism against systemic candidiasis in Danio rerio (Zebrafish)

Nosocomial Candida colonization causes Systemic candidiasis in human with invasive infections in immunocompromised patients. Of all Candida spp., C. albicans is dominant in morbidity of all systemic candidiasis but C. tropicalis is phenomenal in mortality, virulence aspects and resistance development against antifungal drugs. The present study investigated the synergistic anti-virulent activity of myristic acid (MA) and palmitic acid (PA) against insidious dimorphic Candida spp. (C. albicans and C. tropicalis). In vitro and qPCR results revealed the mechanisms of MA-PA combination effectively inhibiting various virulence aspects such as biofilm, hyphal formation, secreted aspartyl proteases, lipases, ergosterol biosynthesis and drug effluxes. Further, in Danio rerio (Zebrafish), the MA-PA treatment increased the survival of animals and also the treated groups showed decreased level of fungal burden compared to the infected controls, after 3^rd day of post infection. Histopathology of vital organs and SEM analysis of skin revealed a drastic recovery and reduced the inflammation of both Candida spp. infections in MA-PA treated animals. In addition, MA-PA treatment reduced the haemolysin and increased the susceptibility of Candida spp. in human blood model. Hence, this study suggested the therapeutic utilization of MA-PA as synergistic combination for their anti-inflammatory potency against systemic candidiasis and candidemia.

Role and Interpretation of Antifungal Susceptibility Testing for the Management of Invasive Fungal Infections

Invasive fungal infections (IFIs) are associated with high mortality rates and timely appropriate antifungal therapy is essential for good outcomes. Emerging antifungal resistance among Candida and Aspergillus spp., the major causes of IFI, is concerning and has led to the increasing incorporation of in vitro antifungal susceptibility testing (AST) to guide clinical decisions. However, the interpretation of AST results and their contribution to management of IFIs remains a matter of debate. Specifically, the utility of AST is limited by the delay in obtaining results and the lack of pharmacodynamic correlation between minimal inhibitory concentration (MIC) values and clinical outcome, particularly for molds. Clinical breakpoints for Candida spp. have been substantially revised over time and appear to be reliable for the detection of azole and echinocandin resistance and for outcome prediction, especially for non-neutropenic patients with candidemia. However, data are lacking for neutropenic patients with invasive candidiasis and some non-albicans Candida spp. (notably emerging Candida auris). For Aspergillus spp., AST is not routinely performed, but may be indicated according to the epidemiological context in the setting of emerging azole resistance among A. fumigatus. For non-Aspergillus molds (e.g., Mucorales, Fusarium or Scedosporium spp.), AST is not routinely recommended as interpretive criteria are lacking and many confounders, mainly host factors, seem to play a predominant role in responses to antifungal therapy. This review provides an overview of the pre-clinical and clinical pharmacodynamic data, which constitute the rationale for the use and interpretation of AST testing of yeasts and molds in clinical practice.

Candida Infection Associated with Salivary Gland-A Narrative Review

Candida species are common global opportunistic pathogens that could repeatedly and chronically cause oral mucosa infection and create an inflammatory environment, leading to organ dysfunction. Oral Candida infections may cause temporary or permanent damage to salivary glands, resulting in the destruction of acinar cells and the formation of scar tissue. Restricted function of the salivary glands leads to discomfort and diseases of the oral mucosa, such as dry mouth and associated infection. This narrative review attempts to summarize the anatomy and function of salivary glands, the associations between Candida and saliva, the effects of Candida infection on salivary glands, and the treatment strategies. Overall, clinicians should proactively manage Candida infections by educating patients on oral hygiene management for vulnerable populations, conducting frequent checks for a timely diagnosis, and providing an effective treatment plan.

Sterol 14α-Demethylase Ligand-Binding Pocket-Mediated Acquired and Intrinsic Azole Resistance in Fungal Pathogens

The fungal cytochrome P450 enzyme sterol 14α-demethylase (SDM) is a key enzyme in the ergosterol biosynthesis pathway. The binding of azoles to the active site of SDM results in a depletion of ergosterol, the accumulation of toxic intermediates and growth inhibition. The prevalence of azole-resistant strains and fungi is increasing in both agriculture and medicine. This can lead to major yield loss during food production and therapeutic failure in medical settings. Diverse mechanisms are responsible for azole resistance. They include amino acid (AA) substitutions in SDM and overexpression of SDM and/or efflux pumps. This review considers AA affecting the ligand-binding pocket of SDMs with a primary focus on substitutions that affect interactions between the active site and the substrate and inhibitory ligands. Some of these interactions are particularly important for the binding of short-tailed azoles (e.g., voriconazole). We highlight the occurrence throughout the fungal kingdom of some key AA substitutions. Elucidation of the role of these AAs and their substitutions may assist drug design in overcoming some common forms of innate and acquired azole resistance.

Potent Synergistic Interactions between Lopinavir and Azole Antifungal Drugs against Emerging Multidrug-Resistant Candida auris

The limited therapeutic options and the recent emergence of multidrug-resistant Candida species present a significant challenge to human medicine and underscore the need for novel therapeutic approaches. Drug repurposing appears as a promising tool to augment the activity of current azole antifungals, especially against multidrug-resistant Candida auris In this study, we evaluated the fluconazole chemosensitization activities of 1,547 FDA-approved drugs and clinical molecules against azole-resistant C. auris This led to the discovery that lopinavir, an HIV protease inhibitor, is a potent agent capable of sensitizing C. auris to the effect of azole antifungals. At a therapeutically achievable concentration, lopinavir exhibited potent synergistic interactions with azole drugs, particularly with itraconazole against C. auris (fractional inhibitory concentration index [ΣFICI] ranged from 0.04 to 0.09). Additionally, the lopinavir/itraconazole combination enhanced the survival rate of C. auris-infected Caenorhabditis elegans by 90% and reduced the fungal burden in infected nematodes by 88.5% (P < 0.05) relative to that of the untreated control. Furthermore, lopinavir enhanced the antifungal activity of itraconazole against other medically important Candida species, including C. albicans, C. tropicalis, C. krusei, and C. parapsilosis Comparative transcriptomic profiling and mechanistic studies revealed that lopinavir was able to significantly interfere with the glucose permeation and ATP synthesis. This compromised the efflux ability of C. auris and consequently enhanced the susceptibility to azole drugs, as demonstrated by Nile red efflux assays. Altogether, these findings present lopinavir as a novel, potent, and broad-spectrum azole-chemosensitizing agent that warrants further investigation against recalcitrant Candida infections.

General hospital outbreak of invasive candidiasis due to azole-resistant Candida parapsilosis associated with an Erg11 Y132F mutation

An increasing number of outbreaks due to resistant non-albicans Candida species have been reported worldwide. Between 2014 and 2016, Candida isolates causing invasive candidiasis were recovered in a Mexican hospital. Isolates were identified to species level and antifungal susceptibility was determined. In the time period studied, 74 invasive candidiasis cases were identified, with 38% (28/74) caused by Candida parapsilosis, out of which 54% (15/28) were fluconazole resistant. The ERG11 gene was sequenced for 12 recoverable fluconazole-resistant C. parapsilosis isolates and SNPs identified. The 12 isolates had one common silent point mutation in ERG11 (T591C) and seven isolates had an additional (A395T) mutation, which corresponded to Y132F. Four of the isolates carrying this mutation were closely related within the same cluster by microsatellite typing. This is the first report of an invasive candidiasis outbreak in Mexico due to azole-resistant C. parapsilosis associated with the Y132F substitution.

Use of Essential Oils in Veterinary Medicine to Combat Bacterial and Fungal Infections

Essential oils (EOs) are secondary metabolites of plants employed in folk medicine for a long time thanks to their multiple properties. In the last years, their use has been introduced in veterinary medicine, too. The study of the antibacterial properties of EOs is of increasing interest, because therapies with alternative drugs are welcome to combat infections caused by antibiotic-resistant strains. Other issues could be resolved by EOs employment, such as the presence of antibiotic residues in food of animal origin and in environment. Although the in vitro antimicrobial activity of EOs has been frequently demonstrated in studies carried out on bacterial and fungal strains of different origins, there is a lack of information about their effectiveness in treating infections in animals. The scientific literature reports some studies about in vitro EOs' activity against animal clinical bacterial and fungal isolates, but in vivo studies are very scanty. The use of EOs in therapy of companion and farm animals should follow careful studies on the toxicity of these natural products in relation to animal species and route of administration. Moreover, considering the different behavior of EOs in relation to both species and strain pathogen, before starting a therapy, an aromatogram should be executed to choose the oil with the best antimicrobial activity.

Physicochemical and Antifungal Properties of Clotrimazole in Combination with High-Molecular Weight Chitosan as a Multifunctional Excipient

Chitosans represent a group of multifunctional drug excipients. Here, we aimed to estimate the impact of high-molecular weight chitosan on the physicochemical properties of clotrimazole–chitosan solid mixtures (CL–CH), prepared by grinding and kneading methods. We characterised these formulas by infrared spectroscopy, differential scanning calorimetry, and powder X-ray diffractometry, and performed in vitro clotrimazole dissolution tests. Additionally, we examined the antifungal activity of clotrimazole–chitosan mixtures against clinical Candida isolates under neutral and acid conditions. The synergistic effect of clotrimazole and chitosan S combinations was observed in tests carried out at pH 4 on Candida glabrata strains. The inhibition of C. glabrata growth reached at least 90%, regardless of the drug/excipient weight ratio, and even at half of the minimal inhibitory concentrations of clotrimazole. Our results demonstrate that clotrimazole and high-molecular weight chitosan could be an effective combination in a topical antifungal formulation, as chitosan acts synergistically with clotrimazole against non-albicans candida strains.