Drug-Resistant Fungi: An Emerging Challenge Threatening Our Limited Antifungal Armamentarium

A novel mannan-specific chimeric antigen receptor M-CAR redirects T cells to interact with Candida spp. hyphae and Rhizopus oryzae spores

Invasive fungal infections (IFIs) are responsible for elevated rates of morbidity and mortality, causing around of 1.5 million deaths annually worldwide. One of the main causative agents of IFIs is Candida albicans, and non-albicans Candida species have emerged as a spreading global public health concernment. Furthermore, COVID-19 has contributed to a boost in the incidence of IFIs, such as mucormycosis, in which Rhizopus oryzae is the most prevalent causative agent. The effector host immune response against IFIs depends on the activity of T cells, which are susceptible to the regulatory effects triggered by fungal virulence factors. The fungal cell wall plays a crucial role as a virulence factor, and its remodeling compromises the development of a specific T-cell response. The redirection of Jurkat T cells to target Candida spp. by recognizing targets expressed on the fungal cell wall can be facilitated using chimeric antigen receptor (CAR) technology. This study generated an M-CAR that contains an scFv with specificity to α-1,6 mannose backbone of fungal mannan, and the expression of M-CAR on the surface of modified Jurkat cells triggered a strong activation against Candida albicans (hyphae form), Candida tropicalis (hyphae form), Candida parapsilosis (pseudohyphal form), and Candida glabrata (yeast form). Moreover, M-CAR Jurkat cells recognized Rhizopus oryzae spores, which induced high expression of cell activation markers. Thus, a novel Mannan-specific CAR enabled strong signal transduction in modified Jurkat cells in the presence of Candida spp. or R. oryzae.

Impact of Invasive Fungal Diseases on Treatment Outcomes in Pediatric Acute Lymphoblastic Leukemia and Lymphoblastic Lymphoma: Insights From a Single-Center Study

BACKGROUND AND AIMS

Invasive fungal diseases (IFD) in children with newly diagnosed acute lymphoblastic leukemia (ALL) and lymphoblastic lymphoma (LBL) are poorly characterized, especially in lower-middle-income countries (LMICs). This study aims to identify the incidence, risk factors, and outcomes of IFD in a pediatric cohort with ALL/LBL.

METHODS

We retrospectively analyzed pediatric patients diagnosed with ALL/LBL between January and December 2023 at a tertiary cancer center in India. Patients were risk-stratified and treated per the modified ICiCLe-ALL-14 protocol. IFDs were classified as proven, probable, and possible according to the revised EORTC/MSG consensus definition.

RESULTS

Among 407 patients, 392(96%) had ALL. The overall incidence of IFD was 25%, with probable/proven infections in 12%. Mold infections predominated (79 cases, 77%), followed by yeast infections (21 cases, 21%). In comparison with patients without IFDs, those with IFDs were more likely to have received dexamethasone (30 vs. 20%; p = 0.009), anthracycline (28 vs. 14%; p = 0.001) during induction and have central venous access (27 vs. 18%; p = 0.008). The 6-week mortality rate of patients with IFD was 15%, rising to 26% in probable/proven cases. Coexisting bacterial infection was associated with increased mortality (odds ratio: 19.2[95%CI: 3.5-105]; p = 0.001).

CONCLUSION

IFDs are common in newly diagnosed ALL/LBL patients in LMICs, particularly during early phases of therapy. These infections are associated with considerable mortality, often compounded by concomitant bacterial sepsis. Given these findings, consideration of antifungal prophylaxis is warranted to mitigate morbidity and mortality due to IFDs.

Illuminating antifungal mode of action and resistance with fluorescent probes

The rise in fungal infections, driven by pathogens resistant to the limited scope of antifungal agents available, poses an increasing threat to global health and the economy. Addressing this challenge requires a thorough understanding of the mechanisms of antifungal agents and the development of advanced resistance diagnostic methods. This opinion manuscript highlights recent advancements in antifungal research, with a focus on chemical biology approaches, particularly the development of fluorescent probes derived from various antifungal agents. These probes reveal new aspects of antifungal activity and provide deeper insights into modes of action and resistance mechanisms. Live cell imaging of fungal pathogens labeled with these probes has uncovered novel strategies to enhance antifungal efficacy, understand virulence factors, and detect resistance. These unique small-molecule tools offer powerful new avenues for addressing the fungal infections crisis, harnessing chemical biology approaches to develop innovative solutions to the global challenges posed by fungi.

Hybrid Bis-(Imidazole/Benzimidazole)-Pyridine Derivatives with Antifungal Activity of Potential Interest in Medicine and Agriculture via Improved Efficiency Methods

Background/Objectives: Nowadays fungal infections are rising serious threats for the human health system and agriculture, mostly because of antifungal resistance, emergence of new fungal pathogens and adverse effects, pressing the scientific world for exploration of new antifungal compounds. Therefore, the aim of this work was to synthesize and to study antifungal activity against human and plant fungi of a new class of hybrid bis-(imidazole/benzimidazole)-pyridine salt derivatives. Methods: The synthesis of the hybrid derivatives was performed using both conventional thermal heating and ultrasound irradiation methods. Results: The use of ultrasound irradiation has the advantages of a dramatic decrease in reaction time and, consequently, a notable acceleration in reaction rate, a remarkable decrease in consumed energy and higher yields. The antifungal activity against five human fungal strains and for plant fungal strains was determined by the disk diffusion method and minimum inhibitory concentration. Conclusions: The tested hybrid derivatives manifest good antifungal activity against the tested strains. Some of the hybrid compounds have very good quasi-nonselective activity against the tested human and plant pathogenic fungi, in some cases close to the control drug fluconazole, respectively, to many antifungal agents commercially used for plant protection.

Subterranean marvels: microbial communities in caves and underground mines and their promise for natural product discovery

Covering: 2014 to 2024Since the dawn of human history, caves have played an intimate role in our existence. From our earliest ancestors seeking shelter from the elements to more recent generations harnessing cave substances for medicinal purposes, caves have served as essential resources and havens. The last 40 years of geomicrobiology research has replaced the outdated perception of subterranean environments as lifeless and unchanging with the realization that vibrant microbial communities have adapted to thrive in extreme conditions over millions of years. The ability of subterranean microbial communities to withstand nutrient deprivation and darkness creates a unique reservoir of untapped biosynthetic potential. These communities offer exciting prospects for medicine (e.g., antimicrobial and antitumor therapies) and biotechnology (e.g., redox chemical properties and biomineralization). This article highlights the significance of caves and mines as reservoirs of microbial diversity, the potential impact of their bioactive compounds on the fields of healthcare and biotechnology, and the significant challenges that must be overcome to access and harness the biotechnological potential of subterranean microbial communities. Additionally, it emphasizes the conservation efforts needed to protect these delicate ecosystems, ensuring the preservation of both ancient traditions and tomorrow's medicines.

An exploration of the ocular mysteries linking nanoparticles to the patho-therapeutic effects against keratitis

Microbial keratitis, a sight-threatening corneal infection, remains a significant global health concern. Conventional therapies using antimicrobial agents often suffers from limitations such as poor drug penetration, side effects, and occurrence of drug resistance, with poor prognosis. Novel treatment techniques, with their unique properties and targeted delivery capabilities, offers a promising solution to overcome these challenges. This review delves into timely update of the state-of-the-art advance therapeutics for keratitis treatment. The diverse microbial origins of keratitis, including viral, bacterial, and fungal infections, exploring their complex pathogenic mechanisms, followed by the drug resistance mechanisms in keratitis pathogens are reviewed briefly. Importantly, the emerging therapeutic techniques for keratitis treatment including piezodynamic therapy, photothermal therapy, photodynamic therapy, nanoenzyme therapy, and metal ion therapy are summarized in this review showcasing their potential to overcome the limitations of traditional treatments. The challenges and future directions for advance therapies and nanotechnology-based approaches are discussed, focusing on safety, targeting strategies, drug resistance, and combination therapies. This review aims to inspire researchers to revolutionize and accelerate the development of functional materials using different therapies for keratitis treatment.

The stress-protectant molecule trehalose mediates fluconazole tolerance in Candida glabrata

The incidence of non-albicans Candida infections has witnessed a substantial rise in recent decades. Candida glabrata (Nakaseomyces glabratus), an opportunistic human fungal pathogen, is accountable for both superficial mucosal and life-threatening bloodstream infections, particularly in immunocompromised individuals. Distinguished by its remarkable resilience to environmental stressors, C. glabrata exhibits intrinsic tolerance to azoles and a high propensity to swiftly develop azole resistance during treatment. The molecular mechanism for the high tolerance is not fully understood. In this work, we investigated the possible role of trehalose in this tolerance. We generated mutants in the C. glabrata TPS1, TPS2, and NTH1 genes, encoding trehalose 6-phosphate synthase (Tps1), trehalose 6-phosphate phosphatase (Tps2), and neutral trehalase (Nth1), respectively. As expected, the tps1∆ strain cannot grow on glucose. The tps2∆ strain demonstrated diminished trehalose accumulation and very high levels of trehalose 6-phosphate (T6P), the biosynthetic intermediate, in comparison to the wild-type (WT) strain. Whereas these higher T6P levels did not affect growth, the lower trehalose levels clearly resulted in lower environmental stress tolerance and a lower susceptibility to fluconazole. More interestingly, the tps2∆ strain completely lost tolerance to fluconazole, characterized by the absence of slow growth at supra-MIC concentrations of this drug. All these phenotypes are reversed in the nth1∆ strain, which accumulates high levels of trehalose. Our findings underscore the role of trehalose in enabling tolerance toward fluconazole in C. glabrata. We further show that the change in tolerance is a result of the effect that trehalose has on the sterol pattern in the cell.

Current strategies in design and synthesis of antifungals hybrid and chimeric diazine derivatives

In the last decades fungal infections became a major threat to human health having an unacceptably occurrence, a high rate of mortality and the number of patients at risk for these infections continue to increase every year. An effective, modern and very useful strategy in antifungal therapy is represented by the use of chimeric and hybrid drugs, most of them being with azaheterocycle skeleton. In this review, we present an overview from the last five years of the most representative achievements in the field of chimeric and hybrid diazine derivatives with antifungal properties. Within this work we emphasize the most relevant data concerning the synthesis, design, Structure Activity Relationships (SAR) correlations and antifungal activity of the main classes of diazine: 1,2-diazine (pyridazine), 1,3-diazine (pyrimidine), 1,4-diazine (pyrazine) and their fused derivatives.

Chemical profile, antioxidant, antifungal, and cytotoxic activities of propolis from the stingless bee Tetragona clavipes

Propolis is derived from plant resin and bees' salivary secretions, are commonly used in folk medicine. Studies on propolis from stingless bees have increased in recent years, highlighting their relevance due to the variety of species and the bioactive components. However, scientific records confirming these activities in species occurring in Brazil are still scarce. In that context, this study aims to determine the chemical profile and the antioxidant, antifungal, and cytotoxic activities of the stingless bees Tetragona clavipes propolis. The hydroalcoholic extract was prepared, and its chemical profile was determined by Fourier transform ion cyclotron resonance mass spectrometry combined with a direct infusion electrospray ionization. Total polyphenols and flavonoid content were determined by colorimetric methods. We determined the antioxidant activity by the ability to scavenge the free radicals 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid). The antifungal activity was evaluated by determining the minimum inhibitory concentration and minimum fungicidal concentration against Aspergillus fumigatus, Trichophyton rubrum, Candida albicans, and Candida parapisilosis. The results revealed high contents of total phenolics and promising antioxidant and antifungal activities. T. clavipes propolis from the rainy season showed better antioxidant and antifungal activities and higher content of flavonoids, with less variability of chemical species. The extracts exhibited fungistatic activity for C. albicans, C. parapisilosis, and A. fumigatus and fungicide for T. rubrum. Additionally, a sample collected during the rainy season demonstrated synergism with fluconazole and amphotericin B for T. rubrum and additivity for C. albicans and C. parapisilosis. In summary, the results of T. clavipes propolis revealed elevated levels of total phenolics, indicating its potential as a rich source of bioactive compounds, significant antioxidant activity, and promising antifungal activity against common pathogenic fungi. These findings contribute to our understanding of the therapeutic potential of T. clavipes propolis and provide a basis for further research and development of natural products for various applications in medicine and healthcare.

Synergistic antifungal effects and mechanisms of amantadine hydrochloride combined with azole antifungal drugs on drug-resistant Candida albicans

Introduction

The increasing resistance of Candida albicans (C. albicans) to conventional antifungal drugs poses a great challenge to the clinical treatment of infections caused by this yeast. Drug combinations are a potential therapeutic approach to overcome the drug- resistance of C. albicans. This study explored the synergistic effects of amantadine hydrochloride (AMH) combined with azole antifungal drugs against drug-resistant C. albicans in vitro and in vivo.

Methods

The in vitro sensitivity of Candida spp. to drugs was determined by the microdilution method. The effect of drugs on the efflux pump activity of C. albicans was determined by the rhodamine 6G tracer method. The egg yolk agar plate method was used to determine the activity of extracellular phospholipase, a C. albicans virulence factor. The Galleria mellonella model of C. albicans infection was used to test the in vivo efficacy of the combination therapy.

Results

In vitro experiments showed that combinations of AMH with azole antifungal drugs had synergistic antifungal effects on planktonic cells of drug-resistant C. albicans, with fractional inhibitory concentration index values of <0.5. The in vivo synergistic effects and mechanism of drug combinations with AMH were further studied using fluconazole (FLC) as a representative azole antifungal drug. In vivo, G. mellonella larvae were used to evaluate the antifungal efficacy of AMH +FLC. AMH + FLC treatment increased the survival rate of larvae infected with drug-resistant C. albicans and reduced tissue invasion. Studies of the mechanism of synergy showed that AMH inhibited drug efflux pump activity in drug-resistant C. albicans, and that AMH + FLC synergistically inhibited early biofilms and the extracellular phospholipase activity of drug-resistant C. albicans.

Conclusion

This study provides strong evidence that combinations of non-antifungal drugs and antifungal drugs can effectively overcome drug-resistant C. albicans infection. Both AMH and FLC are FDA-approved drugs, eliminating concerns about safety. Our findings provide a foundation for further clinical antifungal research.

Inhibition of Fusarium oxysporum growth in banana by silver nanoparticles: In vitro and in vivo assays

Fusarium wilt is a devastating disease that affects banana crops worldwide. In Ecuador, bananas are one of the most important commodities and staple food. Nanoparticles are emerging as innovative solutions to control fungal diseases in plant protection. In this study, in vitro and in vivo assays were carried out to validate Fusarium oxysporum growth and disease inhibition. 96-well plates experiments were used to calculate the IC50 of three different silver nanoparticle formulations (Argovit-1220, Argovit-1221, and Argovit-C) against four Ecuadorian Fusarium strains race 1 (EC15-E-GM1, EC19-LR-GM3, EC35-G-GM6, EC40-M-GM2). More than 95% inhibition rate was obtained at 25 mg L-1 concentration. Fusarium wilt in vivo assay (greenhouse conditions) was carried out with Gros Michel plants, where better control was obtained by applying silver nanoparticles to the roots, reducing disease development by an average of 68%. This study shows that silver nanoparticles have a high antifungal potential for controlling the Fusarium wilt of bananas. To our knowledge, this is the first study to test the potential of AgNPs against Fusarium oxysporum race 1 in vitro and in vivo under greenhouse conditions.

Short-term evolution and dispersal patterns of fluconazole-resistance in Candida auris clade III

The rapid increase in infections caused by the emerging fungal pathogen Candida auris is of global concern, and understanding its expansion is a priority. The phylogenetic diversity of the yeast is clustered in five major clades, among which clade III is particularly relevant, as most of its strains exhibit resistance to fluconazole, reducing the therapeutic alternatives and provoking outbreaks that are difficult to control. In this study, we have investigated the phylogenetic structure of clade III by analyzing a global collection of 566 genomes. We have identified three subgroups within clade III, among which two are genetically most closely related. Moreover, we have estimated the evolutionary rate of clade III to be 2.25e-7 s/s/y (2.87 changes per year). We found that one of these subgroups shows intrinsic resistance to fluconazole and is responsible for the majority of cases within this clade globally. We inferred that this subgroup may have originated around December 2010 (95% High Probability Density (HPD): April 2010-June 2011), and since then it has spread across continents, generating multiple large outbreaks, each with a unique pattern of transmission and dissemination. These results highlight the remarkable ability of the pathogen to adapt to its environment and its rapid global spread, underscoring the urgent need to address this epidemiological challenge effectively.IMPORTANCEThe number of cases affected by Candida auris has increased worryingly worldwide. Among the currently recognized clades, clade III has the highest proportion of fluconazole-resistant cases and is spreading very rapidly, causing large nosocomial outbreaks across the globe. By analyzing complete fungal genomes from around the world, we have confirmed the origin of this clade and unraveled its dispersal patterns in the early 2010s. This finding provides knowledge that may be helpful to the public health authorities for the control of the disease.

Interactions of the emerging fungus Candida auris with Acanthamoeba castellanii reveal phenotypic changes with direct implications on the response to stress and virulence

Candida auris is an emerging fungal pathogen notable for its resistance to multiple antifungals and ability to survive in various environments. Understanding the interactions between C. auris and environmental protozoa, such as Acanthamoeba castellanii, could provide insights into fungal adaptability and pathogenicity. Two C. auris isolates (MMC1 and MMC2) were co-cultured with A. castellanii to examine interaction dynamics, survival, stress responses, growth, virulence, biofilm formation, and antifungal susceptibility. The association of C. auris-A. castellanii varied with a multiplicity of infection (MOI), with MMC2 exhibiting higher association rates at increased MOI than MMC1. Both isolates survived distinctly within A. castellanii, as the MMC1 showed an initial decline and subsequent increase in viability, while MMC2 maintained higher viability for up to 24 h, decreasing afterward. Both isolates exhibited accelerated growth when recovered from A. castellanii. The MMC2 isolate displayed increased resistance to oxidative, osmotic, and thermal stresses upon interaction with A. castellanii, whereas MMC1 showed limited changes. Exposure to A. castellanii also influenced the expression of virulence factors differently, with MMC1 increasing phospholipase and peptidase, while MMC2 upregulated phytase, esterase, hemolysin, and siderophores. Upon contact with A. castellanii, MMC2 enhanced biofilm formation, unlike MMC1. Both isolates increased ergosterol upon interactions, enhancing susceptibility to amphotericin B. However, both isolates were more tolerant to itraconazole and caspofungin, particularly MMC2, which showed differential expression of ergosterol biosynthesis enzymes and increased cell wall polysaccharides. This study reveals that interactions with A. castellanii modulate C. auris physiology and virulence, contributing to its environmental adaptability and resistance to antifungals.

IMPORTANCE

Candida auris has emerged as a critical public health concern due to its resistance to multiple antifungal drugs and ability to survive on surfaces under harsh conditions, mainly due to biofilm formation. The precise origin of this emerging pathogen still awaits elucidation, but interactions with environmental protozoa may have helped C. auris to develop such virulence and resistance traits. In this work, we precisely characterize the interactions of C. auris with the free-living amoeba Acanthamoeba castellanii and how these protozoa may alter the fungal behavior in terms of virulence, thermotolerance, biofilm formation capacity, and drug resistance. It may be essential to understand the various interactions C. auris could perform in the environment, directly impacting the outcome of human infections under the One Health approach.

AIDS-related mycoses: advances, challenges, and future directions

Fungal infections are a major contributor to mortality for people with HIV/AIDS. Recently, researchers, clinicians, industry experts, and policymakers convened for the triennial AIDS-Related Mycoses Meeting to address critical gaps in the management of AIDS-related mycoses. Delegates highlighted several scientifically driven milestones that have significantly reduced fungal-related deaths, and the need to address outstanding challenges in diagnosis, treatment, and research.

The Role of Oxidative Stress in the Antifungal Activity of Two Mollusk Fractions on Resistant Fungal Strains

Fungal infections are a significant global public health challenge because of their widespread occurrence, morbidity, and profound social and economic consequences. Antifungal resistance is also an increasing concern, posing a substantial risk to public health. There is a growing interest in searching for new antifungal drugs isolated from natural sources. This study aimed to evaluate the antifungal activity of novel mollusk fractions against fungal strains resistant to nystatin and amphotericin B. In addition, the role of oxidative stress in the mechanism of damage was determined. The mucus from the garden snail Cornu aspersum (MCa/1-20) and the hemolymph fraction from the marine snail Rapana venosa (HLRv/3-100) were obtained and characterized via 12% sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and mass spectrometric -analyses. The results demonstrate that the spores and biomass of both mollusk fractions have a significant fungicidal effect against Penicillium griseofulvum, and Aspergillus niger. Compared to the control group, the release of intracellular proteins and reducing sugars was significantly increased in the treated groups. The data showed increased levels of oxidative stress biomarkers (lipid peroxidation and oxidatively damaged proteins) and a downregulated antioxidant enzyme defense, corresponding to increased antifungal activity. To our knowledge, this is the first study evaluating oxidative stress as a factor in mollusk fractions' antifungal activity.

How Should we Teach Medicinal Chemistry in Higher Education to Prepare Students for a Future Career as Medicinal Chemists and Drug Designers? - A Teacher's Perspective

In the recent two decades, the multidisciplinary field of medicinal chemistry has undergone several conceptual and technology-driven paradigm changes with significant impact on the skill set medicinal chemists need to acquire during their education. Considering the need for academic medicinal chemistry teaching, this article aims at identifying important skills, competences, and basic knowledge as general learning outcomes based on an analysis of the relevant stakeholders and concludes effective teaching strategies preparing students for a future career as medicinal chemists and drug designers.

Enhancing Flucytosine Anticandidal Activity Using PEGylated Squalene Nanocarrier

There is an emerging necessity for improved therapies against Candida-related infections, with significant implications for global healthcare. Current antifungal agents, limited in number, target specific pathways, but resistance remains a concern. Flucytosine (5FC) exhibits antifungal activity, particularly against Candida. However, monotherapy efficacy is limited, necessitating combination treatments. Herein, we report PEGylated squalene-based nanocarriers for 5FC loading, aiming to enhance its monotherapy efficacy against Candida strains. The loading of 5FC within micelles was achieved using the ultrasound-assisted solvent evaporation method. The 5FC-loaded micelles, together with non-loaded micelles, were thoroughly characterized and analyzed. STEM and DLS analysis confirmed the core-shell morphology with nanometric dimensions along with improved colloidal stability. The quantification of drug loading efficiency and drug loading capacity was calculated using the UV-Vis technique. The in vitro drug-release studies in simulated physiological conditions showed sustained release within 48 hours. Moreover, the release kinetics calculated using mathematical models showed a Fickian diffusion drug release mechanism in simulated physiological conditions with a slower diffusion rate. The in vitro antifungal activity was tested on Candida albicans, Candida glabrata, and Candida parapsilosis. The results showed improved antifungal activity for the nanotherapeutic and unchanged in vitro toxicity toward normal cells, suggesting promising advancements in 5FC therapy.

Luliconazole-loaded nanostructured lipid carrier: formulation, characterization, and in vitro antifungal evaluation against a panel of resistant fungal strains

Luliconazole (LCZ) is a topical imidazole antifungal agent with broad-spectrum activity. However, LCZ encounters challenges such as low aqueous solubility, skin retention, and penetration, which reduce its dermal bioavailability and hinder its efficacy in drug delivery. The aim of the present study was to formulate, characterize, and evaluate the in vitro antifungal efficacy of luliconazole-loaded nanostructured lipid carriers (LCZ-NLCs) against a panel of resistant fungal strains. The LCZ-NLCs were synthesized using a modified emulsification-solvent evaporation technique. Characterization involved assessing parameters such as poly-dispersity index (PDI), zeta potential, encapsulation efficiency (EE %), Field Emission Scanning Electron Microscopy (FESEM), Differential Scanning Calorimetry (DSC) analysis, and Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR). Furthermore, in vitro drug release experiments, analysis of release kinetics, cytotoxicity assessments, and in vitro antifungal susceptibility tests were performed as part of the study. The findings indicated that LCZ-NLCs displayed nanoscale dimensions, uniform dispersion, and a favorable zeta potential. The encapsulation efficiency of LCZ in NLCs was approximately 90%. FESEM analysis revealed spherical nanoparticles with consistent shape. ATR-FTIR analysis indicated no chemical interaction between LCZ and excipients. In vitro drug release experiments demonstrated that LCZ-NLCs notably improved the drug's dissolution rate. The stability testing confirmed consistent colloidal nanometer ranges in the LCZ-NLCs samples. Additionally, cytotoxicity tests revealed no toxicity within the tested concentration. Moreover, in vitro antifungal susceptibility tests demonstrated potent antifungal activity of LCZ-NLCs against the tested resistant fungal isolates. The study findings suggest that the LCZ-NLCs formulation developed in this research could be a promising topical treatment for superficial fungal infections, especially in cases of resistant infections. However, the study needs further ex vivo and in vivo tests to ensure safety and efficacy.

Threats from the Candida parapsilosis complex: the surge of multidrug resistance and a hotbed for new emerging pathogens

SUMMARYCandida parapsilosis is a common agent of candidiasis that has gained increased attention in recent years, culminating with its recent consideration as a high-priority fungal pathogen by the World Health Organization. Reasons for this classification are the recent surge in incidence and the alarmingly growing rates of drug and multidrug resistance. In addition, several closely related species such as Candida metapsilosis and Candida orthopsilosis may represent recently emerged opportunistic pathogens originated from environmental niches through interspecies hybridization. Here, I review recent research focused on the potential origin and spread of drug resistance and of emerging species in this complex. I will also discuss open questions regarding the possible implications of human activities in these two epidemiological phenomena.

Gaining molecular insights towards inhibition of foodborne fungi Aspergillus fumigatus by a food colourant violacein via computational approach

Filamentous Fungal Human Pathogens (FFHPs) such as Aspergillus fumigatus, are growing resistant to currently available antifungal drugs. One possible target, the Nucleoside diphosphate kinase (Ndk) is significant for nucleotide biosynthesis and crucial for fungal metabolism. Violacein, a natural food colorant, was examined for its antifungal effects against Aspergillus fumigatus via computational approach against the Ndk protein. Known and predicted interactions of Ndk with proteins was performed using the STRING application. Molecular docking was performed using Schrodinger Maestro software (V.14.1) under enhanced precision docking, with OPLS4 forcefield. MDS was performed for 500ns under OPLS4 forcefield and the TIP3P solvent system. The geometry optimization for DFT was performed using the Becke 3-parameter exchange functional (B3LYP) method. The Molecular Docking Studies revealed significant interactions with good binding energy between Violacein and Ndk. Subsequent MD Simulations confirmed the stability of Violacein-Ndk complex, compared to the reference ligand-complex, indicating a stable interaction between the protein and violacein. The energy band gap of violacein was found to be 0.072567 eV suggesting its softness with lower kinetic stability and higher chemical reactivity. The results suggest Violacein could potentially disrupt nucleotide metabolism by targeting Ndk, thus demonstrating antifungal activity. However, further experimental validation is required to confirm these computational findings and explore the practical use of Violacein in antifungal treatments.

De novo design of Na+-activated lipopeptides with selective antifungal activity: A promising strategy for antifungal drug discovery

In recent years, invasive fungal infections have posed a significant threat to human health, particularly due to the limited availability of effective antifungal medications. This study responds to the urgent need for powerful and selective antifungal agents by designing and synthesizing a series of lipopeptides with lipoylation at the N-terminus of the antimicrobial peptide I6. Compared to the parent peptide I6, lipopeptides exhibited selective antifungal efficacy in the presence of Na+. Among the variants tested, C8-I6 emerged as the most effective, with an average effective concentration of 5.3 μM against 12 different fungal species. C8-I6 combated fungal infections by disrupting both cytoplasmic and mitochondrial membranes, impairing the proton motive force, generating reactive oxygen species, and triggering apoptosis in fungal cells. Importantly, C8-I6 exhibited minimal hemolysis and cytotoxicity while effectively inhibiting fungal biofilm formation. In vivo experiments further validated the safety and therapeutic potential of C8-I6 in treating fungal skin infections. These findings underscore the significance of lipoylation in enhancing the efficacy of antimicrobial peptides, positioning C8-I6 as a promising candidate in fighting against drug-resistant fungal infections.

Unveiling novel insights: geraniol's enhanced anti-candida efficacy and mechanistic innovations against multidrug-resistant candida strains

OBJECTIVES

This study addressed the need for new treatments for severe Candida infections, especially resistant strains. It evaluated the antifungal potential of geraniol alone and with fluconazole against various Candida spp., including resistant strains, and investigated geraniol's mechanism of action using flow cytometry.

METHODS

The research assessed the inhibitory effects of geraniol on the growth of various Candida species at concentrations ranging from 110 to 883 µg/ml. The study also explored the potential synergistic effects when geraniol was combined with fluconazole. The mechanism of action was investigated through flow cytometry, with a particular emphasis on key enzymes associated with plasma membrane synthesis, membrane permeability changes, mitochondrial membrane depolarization, reactive oxygen species (ROS) induction, and genotoxicity.

RESULTS

Geraniol demonstrated significant antifungal activity against different Candida species, inhibiting growth at concentrations within the range of 110 to 883 µg/ml. The mechanism of action appeared to be multifactorial. Geraniol was associated with the inhibition of crucial enzymes involved in plasma membrane synthesis, increased membrane permeability, induction of mitochondrial membrane depolarization, elevated ROS levels, and the presence of genotoxicity. These effects collectively contributed to cell apoptosis.

CONCLUSIONS

Geraniol, alone and in combination with fluconazole, shows promise as a potential therapeutic option for Candida spp.

INFECTIONS

Its diverse mechanism of action, impacting crucial cellular processes, highlights its potential as an effective antifungal agent. Further research into geraniol's therapeutic applications may aid in developing innovative strategies to address Candida infections, especially those resistant to current therapies.

Antifungal resistance, clinical outcome and clinico-microbiological correlation in ocular infections due to common melanized fungi Curvularia lunata and Lasiodiplodia theobromae in South India

Aim. Melanized fungi were rarely studied for their antifungal resistance (AFR) or clinical outcome, despite rising incidence of melanized fungal ocular infections and AFR in general. We report the antifungal resistance patterns, clinical outcome and clinico-microbiological correlation in two commonly isolated melanized fungi from ocular infections, Curvularia lunata and Lasiodiplodia theobromae, at a tertiary eyecare centre in South India.Gap statement. Despite melanized fungi accounting for a significant proportion of ocular fungal infections in the Indian subcontinent, and despite there being a limited selection of effective antifungal agents available for these infections, the existing data and studies on these issues remain sparse. Therefore, this study aimed to investigate the prevalence of antifungal resistance in two of the most common melanized fungal pathogens in ocular infections, Curvularia lunata and Lasiodiplodia theobromae and correlate it with the treatment given and the clinical outcome in patients.Methodology. Electronic medical records provided the clinical data. Standard broth microdilution was performed for antifungal susceptibility testing (AFST) in 30 isolates (17 C. lunata and 13 L. theobromae) for amphotericin B and natamycin (polyenes): voriconazole, ketoconazole, posaconazole, itraconazole and fluconazole (azoles) and caspofungin (echinocandin). Multidrug resistance (MDR) was defined as resistance to more than or equal to two classes of antifungals. DNA sequencing was performed for the isolates for species confirmation. The multivariate analysis was done for determining poor prognostic factors.Results. AFST showed highest susceptibility of study isolates for voriconazole (83.3% isolates), followed by natamycin (80%), fluconazole (80%), itraconazole (76.7%), ketoconazole (70%), posaconazole (66.7%), caspofungin (66.7%) and lastly amphotericin B (63.3%). All patients empirically received topical natamycin; additional oral ketoconazole/intraocular voriconazole was administered in select few. MDR was strongly associated with poor clinical outcome (multivariate analysis: P = 0.03, odds ratio = 7.8). All patients had microbial keratitis, one progressed to endophthalmitis. Additionally, therapeutic penetrating keratoplasty was required in 40% of cases. Globe salvage was possible in 80% patients, though good visual outcome was seen in only half of them. Both, anatomical and visual outcomes, were poor in 20% of patients. DNA sequencing showed C. lunata as the highest study species.Conclusion. C. lunata and L. theobromae showed varying in vitro antifungal susceptibility and clinical outcome in ocular infections. Voriconazole had significantly higher activity, while amphotericin B had lower activity in vitro for these melanized fungi. MDR isolates showed poorer clinical outcome.

Rosmarinic Acid Exhibits Antifungal and Antibiofilm Activities Against Candida albicans: Insights into Gene Expression and Morphological Changes

Candida species, opportunistic pathogens that cause various infections, pose a significant threat due to their ability to form biofilms that resist antifungal treatments and immune responses. The increasing resistance of Candida spp. and the limited availability of effective treatments have prompted the research of natural compounds as alternative therapies. This study assessed the antifungal properties of RA against Candida species, focusing on its impact on C. albicans biofilms and the underlying mechanisms. The antifungal efficacy of RA was evaluated using the CLSI M27-A3 microdilution method on both fluconazole-susceptible and -resistant strains. Biofilm formation by C. albicans was assessed through a crystal violet assay, while its antibiofilm activity was analyzed using an MTT assay and field emission scanning electron microscopy (FESEM). Gene expression related to biofilm formation was studied using quantitative real-time PCR (qRT-PCR), and statistical analysis was performed with an ANOVA. Among the 28 Candida strains tested, RA exhibited minimum inhibitory concentration (MIC) values ranging from 160 to 1280 μg/mL. At a 640 μg/mL concentration, it significantly reduced the expression of genes associated with adhesion (ALS3, HWP1, and ECE1), hyphal development (UME6 and HGC1), and hyphal cAMP-dependent protein kinase regulators (CYR1, RAS1, and EFG1) in RAS1-cAMP-EFG1 pathway (p < 0.05). FESEM analysis revealed a reduction in hyphal networks and disruptions on the cell surface. Our study is the first to demonstrate the effects of RA on C. albicans adhesion, hyphae development, and biofilm formation through gene expression analysis with findings supported by FESEM. This approach distinguishes our study from previous studies on the effect of RA on Candida. However, the high MIC values of RA limit its antifungal potential. Therefore, more extensive research using innovative methods is required to increase the antifungal effect of RA.

Global research trends and hotspots on human intestinal fungi and health: a bibliometric visualization study

Background

This article employs bibliometric methods and visual maps to delineate the research background, collaborative relationships, hotspots, and trends in the study of gut fungi in human diseases and health.

Methods

Publications related to human gut fungi were retrieved from the Web of Science Core Collection. VOSviewer, CiteSpace, R software and Microsoft Excel were employed to generate visual representations illustrating the contributions made by countries/regions, authors, organizations, and journals. Employing VOSviewer and CiteSpace, we conducted a comprehensive analysis of the retrieved publications, revealing underlying tendencies, research hotspots, and intricate knowledge networks.

Results

This study analyzed a total of 3,954 publications. The United States ranks first in the number of published papers and has the highest number of citations and h-index. Mostafa S Elshahed is the most prolific author. The University of California System is the institution that published the most papers. Frontiers In Microbiology is the journal with the largest number of publications. Three frequently co-cited references have experienced a citation burst lasting until 2024.

Conclusion

Advancements in sequencing technologies have intensified research into human gut fungi and their health implications, shifting the research focus from gut fungal infections towards microbiome science. Inflammatory bowel diseases and Candida albicans have emerged as pivotal areas of interest in this endeavor. Through this study, we have gained a deeper insight into global trends and frontier hotspots within this field, thereby enhancing our understanding of the intricate relationship between gut fungi and human health.

Innate cells and STAT1-dependent signals orchestrate vaccine-induced protection against invasive Cryptococcus infection

Fungal pathogens are underappreciated causes of significant morbidity and mortality worldwide. In previous studies, we determined that a heat-killed, Cryptococcus neoformans fbp1-deficient strain (HK-fbp1) is a potent vaccine candidate. We determined that vaccination with HK-fbp1 confers protective immunity against lethal Cryptococcosis in an interferon γ (IFNγ)-dependent manner. In this study, we set out to uncover cellular sources and relevant targets of the protective effects of IFNγ in response to the HK-fbp1 vaccine. We found that early IFNγ production peaks at day 3 and that monocytes and neutrophils are important sources of this cytokine after vaccination. Neutralization of IFNγ at day 3 results in impaired CCR2+ monocyte recruitment and reduced differentiation into monocyte-derived dendritic cells (Mo-DC). In turn, depletion of CCR2+ cells prior to immunization results in impaired activation of IFNγ-producing CD4 and CD8 T cells. Thus, monocytes are important targets of innate IFNγ and help promote further IFNγ production by lymphocytes. We employed monocyte-fate mapper and conditional STAT1 knockout mice to uncover that STAT1 activation in CD11c+ cells, including alveolar macrophages, Mo-DCs, and monocyte-derived macrophages (Mo-Mac) is essential for HK-fbp1 vaccine-induced protection. Altogether, our aggregate findings suggest critical roles for innate cells as orchestrators of vaccine-induced protection against Cryptococcus infection.IMPORTANCEThe number of patients susceptible to invasive fungal infections across the world continues to rise at an alarming pace yet current antifungal drugs are often inadequate. Immune-based interventions and novel antifungal vaccines hold the promise of significantly improving patient outcomes. In previous studies, we identified a Cryptococcus neoformans mutant strain (Fbp1-deficient) as a potent, heat-inactivated vaccine candidate capable of inducing homologous and heterologous antifungal protection. In this study, we used a combination of methods together with a cohort of conditional knockout mouse strains to interrogate the roles of innate cells in the orchestration of vaccine-induced antifungal protection. We uncovered novel roles for neutrophils and monocytes as coordinators of a STAT1-dependent cascade of responses that mediate vaccine-induced protection against invasive cryptococcosis. This new knowledge will help guide the future development of much-needed antifungal vaccines.

Host immune response against fungal biofilms

Fungal biofilms are a multilayered community of cells attached to mucosal or abiotic surfaces enclosed in a coating of self-produced extracellular polymeric matrix. The sheer density of cells protected by a polymeric shield not only makes the biofilm impermeable to antimicrobials or immune cells but also hidden from host recognition. Biofilms also serve as a reservoir of drug-resistant persister cells and dispersal cells armored with virulence factors adept at evading the immune system. Here, we summarize the latest knowledge on the immunomodulatory properties of biofilms formed by Candida species and by other biofilm-forming fungal pathogens such as Aspergillus and Cryptococcus. Finally, we deliberate on promising strategies to help activate the immune system for combating fungal biofilms.

Anticandidal activity of Croton heliotropiifolius Kunth essential oil is enhanced by N-acetylcysteine and itraconazole

Aim: Evaluate the anticandidal effect of Croton heliotropiifolius Kunth essential oil and its interaction with azoles and N-acetylcysteine (NAC) against planktonic cells and biofilms.Materials & methods: Broth microdilution and checkerboard methods were used to evaluate the individual and combined activity with fluconazole and itraconazole (ITRA). The antibiofilm effect of the oil was assessed in 96-well plates alone and combined with ITRA and NAC, and cytotoxicity determined by MTT.Results: The oil inhibited all Candida species growth. The activity was enhanced when associated with ITRA and NAC for planktonic cells and biofilms in formation. The effective concentrations were lower than the toxic ones to V79 cells.Conclusion: C. heliotropiifolius Kunth essential oil is an anticandidal alternative, and can be associated with ITRA and NAC.

Promoting antifungal stewardship through an antifungal multidisciplinary team in a paediatric and adult tertiary centre in the UK

Background

Invasive fungal infections (IFIs) present significant challenges, especially among immunocompromised patients, with associated high morbidity, mortality and significant economic impact. Diagnostic difficulties and the emergence of antifungal resistance necessitates enhanced antifungal stewardship (AFS) efforts.

Methods

We report outcomes from a review of our multidisciplinary approach to AFS, based in a 1300-bed teaching hospital in the South-West of England. Retrospectively reviewing all adult and paediatric cases over 12 months in 2022, we investigated demographics, diagnosis, antifungal therapy and adherence to AFS advice, including clinical, mycological, financial and teamwork metrics. Data were extracted from our AFS database, supported by pharmacy records.

Results

The AFS multidisciplinary team (MDT) reviewed 111 patients, with 30 day and 1 year mortality of 22.7% and 35.4%, respectively. IFIs classified as proven accounted for 26%, with fungal pathogens identified in 36.3% of cases. Antifungal consumption (by 25.1%) and expenditure (by 59.9%) decreased from 2018 to 2022. The AFS MDT issued 324 recommendations, with a 93% acceptance rate.

Conclusions

Our approach to AFS, centred around a weekly MDT, demonstrated improvements in IFI management, antifungal consumption and cost-efficiency. This single-centre study highlights the value of a comprehensive, collaborative approach to AFS involving experts in mycology, infection, radiology, antifungal therapies and clinical teams. The programme's success in paediatric and adult populations and the near-universal acceptance of its recommendations show its potential as a model for replication. It represents a model for enhancing patient care and AFS practices, with future directions aimed at expanding service reach and the integration of further rapid diagnostic modalities.

Elucidation of furanone as ergosterol pathway inhibitor in Cryptococcus neoformans

In the era of antiretroviral therapy, the prevalence of Cryptococcal infection among HIV patients in developed countries has decreased considerably. However, C. neoformans ranks top among the critical priority pathogen that affects a wide range of immunocompromised individuals. The threat of C. neoformans is because of its incredibly multifaceted intracellular survival capabilities. Cell membrane sterols especially ergosterol and enzymes of its biosynthetic pathway are considered fascinating drug targets because of their structural stability. In this study, the ergosterol biosynthetic enzymes were modeled and docked with furanone derivatives. Among the tested ligands Compound 6 has shown a potential interaction with Lanosterol 14 α-demethylase. This best-docked protein-ligand complex was taken further to molecular dynamics simulation. In addition, Compound 6 was synthesized and an in vitro study was conducted to quantify the ergosterol in Compound 6 treated cells. Altogether the computational and in vitro study demonstrates that Compound 6 has anticryptococcal activity by targeting the biosynthetic pathway of ergosterol.Communicated by Ramaswamy H. Sarma.

Tackling multi-drug resistant fungi by efflux pump inhibitors

The emergence of multidrug-resistant fungi is of grave concern, and its infections are responsible for significant deaths among immunocompromised patients. The treatment of fungal infections primarily relies on a clinical class of antibiotics, including azoles, polyenes, echinocandins, polyketides, and a nucleotide analogue. However, the incidence of fungal infections is increasing as the treatment for human and plant fungal infections overlaps with antifungal drugs. The need for new antifungal agents acting on different targets than known targets is undeniable. Also, the pace at which loss of fungal susceptibility to antibiotics cannot be undermined. There are several modes by which fungi can develop resistance to antibiotics, including reduced drug uptake, drug target alteration, and a reduction in the cellular concentration of the drug due to active extrusions and biofilm formation. The efflux pump's overexpression in the fungi primarily reduced the antibiotic's concentration to a sub-lethal concentration, thus responsible for developing resistant fungus strains. Several strategies are used to check antibiotic resistance in multi-drug resistant fungi, including synthesizing antibiotic analogs and giving antibiotics in combination therapies. Among them, the efflux pump protein inhibitors are considered potential adjuvants to antibiotics and can block the efflux of antibiotics by inhibiting efflux pump protein transporters. Moreover, it can sensitize the antifungal drugs to multi-drug resistant fungi with overexpressed efflux pump proteins. This review discusses the natural lead molecules, repurposable drugs, and formulation strategies to overcome the efflux pump activity in the fungi.

Harnessing Machine Learning to Uncover Hidden Patterns in Azole-Resistant CYP51/ERG11 Proteins

Fungal resistance is a public health concern due to the limited availability of antifungal resources and the complexities associated with treating persistent fungal infections. Azoles are thus far the primary line of defense against fungi. Specifically, azoles inhibit the conversion of lanosterol to ergosterol, producing defective sterols and impairing fluidity in fungal plasmatic membranes. Studies on azole resistance have emphasized specific point mutations in CYP51/ERG11 proteins linked to resistance. Although very insightful, the traditional approach to studying azole resistance is time-consuming and prone to errors during meticulous alignment evaluation. It relies on a reference-based method using a specific protein sequence obtained from a wild-type (WT) phenotype. Therefore, this study introduces a machine learning (ML)-based approach utilizing molecular descriptors representing the physiochemical attributes of CYP51/ERG11 protein isoforms. This approach aims to unravel hidden patterns associated with azole resistance. The results highlight that descriptors related to amino acid composition and their combination of hydrophobicity and hydrophilicity effectively explain the slight differences between the resistant non-wild-type (NWT) and WT (nonresistant) protein sequences. This study underscores the potential of ML to unravel nuanced patterns in CYP51/ERG11 sequences, providing valuable molecular signatures that could inform future endeavors in drug development and computational screening of resistant and nonresistant fungal lineages.

Yeast Particle Encapsulation of Azole Fungicides for Enhanced Treatment of Azole-Resistant Candida albicans

Addressing the growing problem of antifungal resistance in medicine and agriculture requires the development of new drugs and strategies to preserve the efficacy of existing fungicides. One approach is to utilize delivery technologies. Yeast particles (YPs) are 3-5 µm porous, hollow microspheres, a byproduct of food-grade Saccharomyces cerevisiae yeast extract manufacturing processes and an efficient and flexible drug delivery platform. Here, we report the use of YPs for encapsulation of tetraconazole (TET) and prothioconazole (PRO) with high payload capacity and stability. The YP PRO samples were active against both sensitive and azole-resistant strains of Candida albicans. The higher efficacy of YP PRO versus free PRO is due to interactions between PRO and saponifiable lipids in the YPs. Encapsulation of PRO in glucan lipid particles (GLPs), a highly purified form of YPs that do not contain saponifiable lipids, did not result in enhanced PRO activity. We evaluated the co-encapsulation of PRO with a mixture of the terpenes: geraniol, eugenol, and thymol. Samples co-encapsulating PRO and terpenes in YPs or GLPs were active on both sensitive and azole-resistant C. albicans. These approaches could lead to the development of more effective drug combinations co-encapsulated in YPs for agricultural or GLPs for pharmaceutical applications.

[Clinical features and prognosis of hepatosplenic candidiasis in patients with hematopathy]

Hepatosplenic candidiasis (HSC) is a rare type of candidiasis that can occur in patients with hematologic malignancies, hematopoietic stem cell transplantation. At present, there is still a lack of studies on HSC in patients with hematologic disorders. Based on The Chinese Guidelines for the Diagnosis and Treatment of Invasive Fungal Disease in Patients with Hematological Disorders and Cancers (the 6th revision), We retrospectively analyzed the clinical characteristics and prognosis of patients with HSC treated in Peking University Institute of Hematology from 2008 to 2022. Finally, eighteen patients were included, with 1 (5.6%) proven, 2 (11.1%) probable, and 15 (83.3%) possible HSC. Among them, 3 (16.7%) patients occurred after haploid hematopoietic stem cell transplantation and 15 (83.3%) patients occurred after chemotherapy. 6 (33.3%) patients had positive blood cultures, including 4 cases of Candida tropicalis and 2 cases of Candida albicans. At 4 weeks of antifungal therapy, 10 (58.8%) patients achieved partial response (PR), At 8 weeks, 1 (6.3%) patients achieved complete response and 10 (62.5%) patients achieved PR. At 6 months after diagnosis, 3 (16.7%) patients died of hematopoietic recurrence, and none of them died of HSC. As a rare fungal infection disease, HSC has a low positive rate of microbiological and histological examinations, a persistent treat cycle, and has difficulty in remission, reminding us of the need for vigilance in patients with hematopoietic disorders and persistent fever.

Phenotypical Differences at the Physiological and Clinical Level between Two Genetically Closely Related Clavispora lusitaniae Strains Isolated from Patients

The occurrence of non-albicans species within the genus Candida poses a major challenge in the clinical setting. Clavispora lusitaniae, formerly known as Candida lusitaniae, has gained attention due to its potential multidrug resistance, particularly to amphotericin B (AmB). While intrinsic resistance to AmB is rare, secondary resistance may develop during treatment due to phenotypic rearrangement and the reorganization of the cell wall. Although there is evidence of genetic variability within C. lusitaniae, comprehensive genomic studies are lacking. This study examines the physiological differences within Candida species and focuses on the medical implications of this. Using two case reports, significant physiological and resistance differences between two strains of C. lusitaniae are demonstrated, highlighting the need for further research into genetic variability. While one strain showed higher resistance to antifungal drugs and slower growth compared to Strain 2, both strains showed minimal beta-D-glucan production, suggesting alternative pathogenic mechanisms. The study underlines the importance of understanding microbial adaptation and selection mechanisms, especially in the clinical setting, to effectively combat emerging drug resistance. Furthermore, research is needed to clarify the complex interplay between environmental causes, physiological traits, and the mechanisms of drug resistance in C. lusitaniae.

Fighting Emerging Caspofungin-Resistant Candida Species: Mitigating Fks1-Mediated Resistance and Enhancing Caspofungin Efficacy by Chitosan

Invasive candidiasis poses a worldwide threat because of the rising prevalence of antifungal resistance, resulting in higher rates of morbidity and mortality. Additionally, Candida species, which are opportunistic infections, have significant medical and economic consequences for immunocompromised individuals. This study explores the antifungal potential of chitosan to mitigate caspofungin resistance in caspofungin-resistant Candida albicans, C. krusei, and C. tropicalis isolates originating from human and animal sources using agar well diffusion, broth microdilution tests, and transmission electron microscope (TEM) analysis of treated Candida cells. Reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) was performed to assess the expression of SAGA complex genes (GCN5 and ADA2) and the caspofungin resistance gene (FKS) in Candida species isolates after chitosan treatment. The highest resistance rate was observed to ketoconazole (80%) followed by clotrimazole (62.7%), fluconazole (60%), terbinafine (58%), itraconazole (57%), miconazole (54.2%), amphotericin B (51.4%), voriconazole (34.28%), and caspofungin (25.7%). Nine unique FKS mutations were detected, including S645P (n = 3 isolates), S645F, L644F, S645Y, L688M, E663G, and F641S (one isolate in each). The caspofungin minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) values before chitosan treatment ranged from 2 to 8 µg/mL and 4 to 16 µg/mL, respectively. However, the MIC and MFC values were decreased after chitosan treatment (0.0625-1 µg/mL) and (0.125-2 µg/mL), respectively. Caspofungin MIC was significantly decreased (p = 0.0007) threefold following chitosan treatment compared with the MIC values before treatment. TEM analysis revealed that 0.5% chitosan disrupted the integrity of the cell surface, causing irregular morphologies and obvious aberrant changes in cell wall thickness in caspofungin-resistant and sensitive Candida isolates. The cell wall thickness of untreated isolates was 0.145 μm in caspofungin-resistant isolate and 0.125 μm in sensitive isolate, while it was significantly lower in chitosan-treated isolates, ranging from 0.05 to 0.08 μm when compared with the cell wall thickness of sensitive isolate (0.03 to 0.06 μm). Moreover, RT-qPCR demonstrated a significant (p < 0.05) decrease in the expression levels of histone acetyltransferase genes (GCN5 and ADA2) and FKS gene of caspofungin-resistant Candida species isolates treated with 0.5% chitosan when compared with before treatment (fold change values ranged from 0.001 to 0.0473 for GCN5, 1.028 to 4.856 for ADA2, and 2.713 to 12.38 for FKS gene). A comparison of the expression levels of cell wall-related genes (ADA2 and GCN5) between caspofungin-resistant and -sensitive isolates demonstrated a significant decrease following chitosan treatment (p < 0.001). The antifungal potential of chitosan enhances the efficacy of caspofungin against various caspofungin-resistant Candida species isolates and prevents the development of further antifungal resistance. The results of this study contribute to the progress in repurposing caspofungin and inform a development strategy to enhance its efficacy, appropriate antifungal activity against Candida species, and mitigate resistance. Consequently, chitosan could be used in combination with caspofungin for the treatment of candidiasis.

Azole resistance in Aspergillus fumigatus- comprehensive review

Aspergillus fumigatus is a ubiquitous filamentous fungus commonly found in the environment. It is also an opportunistic human pathogen known to cause a range of respiratory infections, such as invasive aspergillosis, particularly in immunocompromised individuals. Azole antifungal agents are widely used for the treatment and prophylaxis of Aspergillus infections due to their efficacy and tolerability. However, the emergence of azole resistance in A. fumigatus has become a major concern in recent years due to their association with increased treatment failures and mortality rates. The development of azole resistance in A. fumigatus can occur through both acquired and intrinsic mechanisms. Acquired resistance typically arises from mutations in the target enzyme, lanosterol 14-α-demethylase (Cyp51A), reduces the affinity of azole antifungal agents for the enzyme, rendering them less effective, while intrinsic resistance refers to a natural resistance of certain A. fumigatus isolates to azole antifungals due to inherent genetic characteristics. The current review aims to provide a comprehensive overview of azole antifungal resistance in A. fumigatus, discusses underlying resistance mechanisms, including alterations in the target enzyme, Cyp51A, and the involvement of efflux pumps in drug efflux. Impact of azole fungicide uses in the environment and the spread of resistant strains is also explored.

Impact of climate change and natural disasters on fungal infections

The effects of climate change and natural disasters on fungal pathogens and the risks for fungal diseases remain incompletely understood. In this literature review, we examined how fungi are adapting to an increase in the Earth's temperature and are becoming more thermotolerant, which is enhancing fungal fitness and virulence. Climate change is creating conditions conducive to the emergence of new fungal pathogens and is priming fungi to adapt to previously inhospitable environments, such as polluted habitats and urban areas, leading to the geographical spread of some fungi to traditionally non-endemic areas. Climate change is also contributing to increases in the frequency and severity of natural disasters, which can trigger outbreaks of fungal diseases and increase the spread of fungal pathogens. The populations mostly affected are the socially vulnerable. More awareness, research, funding, and policies on the part of key stakeholders are needed to mitigate the effects of climate change and disaster-related fungal diseases.

Synergistic activity of crocin and crocin loaded in niosomes alone and in combination with fluconazole against Candida albicans isolates: In vitro and in silico study

INTRODUCTION

Since the drug resistance in Candida species is becoming a serious clinical challenge, novel alternative therapeutic options, particularly herbal medicine, have attracted increasing interest. This study aimed to pinpoint the potential antifungal activity of crocin (Cro), the efficacy of the niosomal formulation of Cro (NCro), and the synergistic activity of both formulations in combination with fluconazole (FLC) against susceptible and resistant C. albicans isolates.

MATERIAL AND METHODS

NCro was formulated using the heating method. The in vitro antimycotic activity of Cro, NCro, and FLC was evaluated. Checkerboard and isobologram assays evaluated the interaction between both formulations of Cro and FLC. Necrotic and apoptotic effects of different agents were analyzed using the flow cytometry method. In silico study was performed to examine the interactions between Lanosterol 14 alpha-demethylase and Cro as a part of our screening compounds with antifungal properties.

RESULTS

NCro exhibited high entrapment efficiency up to 99.73 ± 0.54, and the mean size at 5.224 ± 0.618 µm (mean ± SD, n = 3). Both formulations of Cro were shown to display good anticandidal activity against isolates. The synergistic effect of the NCro in combination with FLC is comparable to Cro (P-value =0.03). Apoptotic indicators confirmed that tested compounds caused cell death in isolates. The docking study indicated that Cro has interactivity with the protein residue of 14α-demethylase.

CONCLUSION

The results showed a remarkable antifungal effect by NCro combined with FLC. Natural compounds, particularly nano-sized carrier systems, can act as an effective therapeutic option for further optimizing fungal infection treatment.

Holotoxin A1 from Apostichopus japonicus inhibited oropharyngeal and intra-abdominal candidiasis by inducing oxidative damage in Candida albicans

BACKGROUND AND PURPOSE

The holotoxin A1, isolated from Apostichopus japonicus, exhibits potent antifungal activities, but the mechanism and efficacy against candidiasis are unclear. In this study we have studied the antifungal effects and mechanism of holotoxin A1 against Candida albicans and in murine oropharyngeal and intra-abdominal candidiasis.

EXPERIMENTAL APPROACH

The antifungal effect of holotoxin A1 against C. albicans was tested in vitro. To explore the antifungal mechanism of holotoxin A1, the transcriptome, ROS levels, and mitochondrial function of C. albicans was evaluated. Effectiveness and systematic toxicity of holotoxin A1 in vivo was assessed in the oropharyngeal and intra-abdominal candidiasis models in mice.

KEY RESULTS

Holotoxin A1 was a potent fungicide against C. albicans SC5314, clinical strains and drug-resistant strains. Holotoxin A1 inhibited oxidative phosphorylation and induced oxidative damage by increasing intracellular accumulation of ROS in C. albicans. Holotoxin A1 induced dysfunction of mitochondria by depolarizing the mitochondrial membrane potential and reducing the production of ATP. Holotoxin A1 directly inhibited the enzymatic activity of mitochondrial complex I and antagonized with the rotenone, an inhibitor of complex I, against C. albicans. Meanwhile, the complex I subunit NDH51 null mutants showed a decreased susceptibility to holotoxin A1. Furthermore, holotoxin A1 significantly reduced fungal burden and infections with no significant systemic toxicity in oropharyngeal and intra-abdominal candidiasis in murine models.

CONCLUSION AND IMPLICATIONS

Holotoxin A1 is a promising candidate for the development of novel antifungal agents against both oropharyngeal and intra-abdominal candidiasis, especially when caused by drug-resistant strains.

Synthesis, In Silico Study, and In Vitro Antifungal Activity of New 5-(1,3-Diphenyl-1H-Pyrazol-4-yl)-4-Tosyl-4,5-Dihydrooxazoles

The increase in multi-drug resistant Candida strains has caused a sharp rise in life-threatening fungal infections in immunosuppressed patients, including those with SARS-CoV-2. Novel antifungal drugs are needed to combat multi-drug-resistant yeasts. This study aimed to synthesize a new series of 2-oxazolines and evaluate the ligands in vitro for the inhibition of six Candida species and in silico for affinity to the CYP51 enzymes (obtained with molecular modeling and protein homology) of the same species. The 5-(1,3-diphenyl-1H-pyrazol-4-yl)-4-tosyl-4,5-dihydrooxazoles 6a-j were synthesized using the Van Leusen reaction between 1,3-diphenyl-4-formylpyrazoles 4a-j and TosMIC 5 in the presence of K2CO3 or KOH without heating, resulting in short reaction times, high compound purity, and high yields. The docking studies revealed good affinity for the active site of the CYP51 enzymes of the Candida species in the following order: 6a-j > 4a-j > fluconazole (the reference drug). The in vitro testing of the compounds against the Candida species showed lower MIC values for 6a-j than 4a-j, and for 4a-j than fluconazole, thus correlating well with the in silico findings. According to growth rescue assays, 6a-j and 4a-j (like fluconazole) inhibit ergosterol synthesis. The in silico toxicity assessment evidenced the safety of compounds 6a-j, which merit further research as possible antifungal drugs.

Poacic Acid, a Plant-Derived Stilbenoid, Augments Cell Wall Chitin Production, but Its Antifungal Activity Is Hindered by This Polysaccharide and by Fungal Essential Metals

Climate and environmental changes have modified the habitats of fungal pathogens, inflicting devastating effects on livestock and crop production. Additionally, drug-resistant fungi are increasing worldwide, driving the urgent need to identify new molecular scaffolds for the development of antifungal agents for humans, animals, and plants. Poacic acid (PA), a plant-derived stilbenoid, was recently discovered to be a novel molecular scaffold that inhibits the growth of several fungi. Its antifungal activity has been associated with perturbation of the production/assembly of the fungal cell wall β-1,3-glucan, but its mode of action is not resolved. In this study, we investigated the antifungal activity of PA and its derivatives on a panel of yeast. PA had a fungistatic effect on S. cerevisiae and a fungicidal effect on plasma membrane-damaged Candida albicans mutants. Live cell fluorescence microscopy experiments revealed that PA increases chitin production and modifies its cell wall distribution. Chitin production and cell growth returned to normal after prolonged incubation. The antifungal activity of PA was reduced in the presence of exogenous chitin, suggesting that the potentiation of chitin production is a stress response that helps the yeast cell overcome the effect of this antifungal stilbenoid. Growth inhibition was also reduced by metal ions, indicating that PA affects the metal homeostasis. These findings suggest that PA has a complex antifungal mechanism of action that involves perturbation of the cell wall β-1,3-glucan production/assembly, chitin production, and metal homeostasis.

Approaches for identifying and measuring heteroresistance in azole-susceptible Candida isolates

Heteroresistance to antifungal agents poses a significant challenge in the treatment of fungal infections. Currently, the absence of established methods for detecting and measuring heteroresistance impedes progress in understanding this phenomenon in fungal pathogens. In response to this gap, we present a comprehensive set of new and optimized methods designed to detect and quantify azole heteroresistance in Candida albicans. Here, we define two primary assays for measuring heteroresistance: population analysis profiling, based on growth on solid medium, and single-cell assays, based on growth in liquid culture. We observe good correlations between the measurements obtained with liquid and solid assays, validating their utility for studying azole heteroresistance. We also highlight that disk diffusion assays could serve as an additional tool for the rapid detection of heteroresistance. These methods collectively provide a versatile toolkit for researchers seeking to assess heteroresistance in C. albicans. They also serve as a critical step forward in the characterization of antifungal heteroresistance, providing a framework for investigating this phenomenon in diverse fungal species and in the context of other antifungal agents. Ultimately, these advancements will enhance our ability to effectively measure antifungal drug responses and combat fungal infections.IMPORTANCEHeteroresistance involves varying antimicrobial susceptibility within a clonal population. This phenomenon allows the survival of rare resistant subpopulations during drug treatment, significantly complicating the effective management of infections. However, the absence of established detection methods hampers progress in understanding this phenomenon in human fungal pathogens. We propose a comprehensive toolkit to address this gap in the yeast Candida albicans, encompassing population analysis profiling, single-cell assays, and disk diffusion assays. By providing robust and correlated measurements through both solid and liquid assays, this work will provide a framework for broader applications across clinically relevant Candida species. These methods will enhance our ability to understand this phenomenon and the failure of antifungal therapy.

New thiazolyl-isoxazole derivatives as potential anti-infective agents: design, synthesis, in vitro and in silico antimicrobial efficacy

Antimicrobial resistance threatens the efficacious prevention and treatment of infectious diseases caused by microorganisms. To combat microbial infections, the need for new drug candidates is essential. In this context, the design, synthesis, antimicrobial screening, and in silico study of a new series of 5-aryl-3-(2-arylthiazol-4-yl)isoxazole (9a-t) have been reported. The structure of new compounds was confirmed by spectrometric methods. Compounds 9a-t were evaluated for in vitro antitubercular and antimicrobial activity. Against M. tuberculosis H37Rv, fourteen compounds showed good to excellent antitubercular activity with MIC 2.01-9.80 µM. Compounds 9a, 9b, and 9r showed four-fold more activity than the reference drug isoniazid. Nine compounds, 9a, 9b, 9d, 9e, 9i, 9q, 9r, 9s, and 9t, showed good antibacterial activity against E. coli with MIC 7.8-15.62 µg/mL. Against A. niger, four compounds showed good activity with MIC 31.25 µg/mL. Against C. albicans, all twenty compounds reported excellent to good activity with MIC 7.8-31.25 µg/mL. Compounds 9c-e, 9g-j, and 9q-t showed comparable activity concerning the reference drug fluconazole. The compounds 9a-t were screened for cytotoxicity against 3t3l1 cell lines and found to be less or non-cytotoxic. The in silico study exposed that these compounds displayed high affinity towards the M. tuberculosis targets PanK, DprE1, DHFR, PknA, KasA, and Pks13, and C. albicans targets NMT, CYP51, and CS. The compound 9r was evaluated for structural dynamics and molecular dynamics simulations. The potent antitubercular and antimicrobial activity of 5-aryl-3-(2-arylthiazol-4-yl)isoxazole (9a-t) derivatives has recommended that these compounds could assist in treating microbial infections.

Recent gene selection and drug resistance underscore clinical adaptation across Candida species

Understanding how microbial pathogens adapt to treatments, humans and clinical environments is key to infer mechanisms of virulence, transmission and drug resistance. This may help improve therapies and diagnostics for infections with a poor prognosis, such as those caused by fungal pathogens, including Candida. Here we analysed genomic variants across approximately 2,000 isolates from six Candida species (C. glabrata, C. auris, C. albicans, C. tropicalis, C. parapsilosis and C. orthopsilosis) and identified genes under recent selection, suggesting a highly complex clinical adaptation. These involve species-specific and convergently affected adaptive mechanisms, such as adhesion. Using convergence-based genome-wide association studies we identified known drivers of drug resistance alongside potentially novel players. Finally, our analyses reveal an important role of structural variants and suggest an unexpected involvement of (para)sexual recombination in the spread of resistance. Our results provide insights on how opportunistic pathogens adapt to human-related environments and unearth candidate genes that deserve future attention.

Treatment of onychomycosis in an era of antifungal resistance: Role for antifungal stewardship and topical antifungal agents

A growing body of literature has marked the emergence and spread of antifungal resistance among species of Trichophyton, the most prevalent cause of toenail and fingernail onychomycosis in the United States and Europe. We review published data on rates of oral antifungal resistance among Trichophyton species; causes of antifungal resistance and methods to counteract it; and in vitro data on the role of topical antifungals in the treatment of onychomycosis. Antifungal resistance among species of Trichophyton against terbinafine and itraconazole-the two most common oral treatments for onychomycosis and other superficial fungal infections caused by dermatophytes-has been detected around the globe. Fungal adaptations, patient characteristics (e.g., immunocompromised status; drug-drug interactions), and empirical diagnostic and treatment patterns may contribute to reduced antifungal efficacy and the development of antifungal resistance. Antifungal stewardship efforts aim to ensure proper antifungal use to limit antifungal resistance and improve clinical outcomes. In the treatment of onychomycosis, critical aspects of antifungal stewardship include proper identification of the fungal infection prior to initiation of treatment and improvements in physician and patient education. Topical ciclopirox, efinaconazole and tavaborole, delivered either alone or in combination with oral antifungals, have demonstrated efficacy in vitro against susceptible and/or resistant isolates of Trichophyton species, with low potential for development of antifungal resistance. Additional real-world long-term data are needed to monitor global rates of antifungal resistance and assess the efficacy of oral and topical antifungals, alone or in combination, in counteracting antifungal resistance in the treatment of onychomycosis.

Antimicrobial Potential of Natural Compounds of Zingiberaceae Plants and their Synthetic Analogues: A Scoping Review of In vitro and In silico Approaches

AIMS

There has been increased scientific interest in bioactive compounds and their synthetic derivatives to promote the development of antimicrobial agents that could be used sustainably and overcome antibiotic resistance.

METHODS

We conducted this scoping review to collect evidence related to the antimicrobial potential of diverse natural compounds from Zingiberaceae plants and their synthetic derivatives. We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Extension for Scoping Reviews guidelines. The literature search was conducted using PubMed, Web of Science and Scopus electronic databases for relevant studies published from 2012 to 2023. A total of 28 scientific studies fulfilled the inclusion criteria. The authors of these studies implemented in vitro and in silico methods to examine the antimicrobial potency and underlying mechanisms of the investigated compounds.

RESULT

The evidence elucidates the antimicrobial activity of natural secondary metabolites from Zingiberaceae species and their synthetic derivatives against a broad panel of gram-positive and gram-negative bacteria, fungi and viruses.

CONCLUSION

To date, researchers have proposed the application of bioactive compounds derived from Zingiberaceae plants and their synthetic analogues as antimicrobial agents. Nevertheless, more investigations are required to ascertain their efficacy and to broaden their commercial applicability.

Green synthesis of biogenic selenium nanoparticles functionalized with ginger dietary extract targeting virulence factor and biofilm formation in Candida albicans

To treat the systemic infections caused by Candida albicans (C. albicans), various drugs have been used, however, infections still persisted due to virulence factors and increasing antifungal resistance. As a solution to this problem, we synthesized selenium nanoparticles (SeNPs) by using Bacillus cereus bacteria. This is the first study to report a higher (70 %) reduction of selenite ions into SeNPs in under 6 h. The as-synthesized, biogenic SeNPs were used to deliver bioactive constituents of aqueous extract of ginger for inhibiting the growth and biofilm (virulence factors) in C. albicans. UV-visible spectroscopy revealed a characteristic absorption at 280 nm, and Raman spectroscopy showed a characteristic peak shift at 253 cm-1 for the biogenic SeNPs. The synthesized SeNPs are spherical with 240-250 nm in size as determined by electron microscopy. Fourier transform infrared spectroscopy confirmed the functionalization of antifungal constituents of ginger over the SeNPs (formation of Ginger@SeNPs nanoconjugates). In contrast to biogenic SeNPs, nanoconjugates were active against C. albicans for inhibiting growth and biofilm formation. In order to reveal antifungal mechanism of nanoconjugates', real-time polymerase chain reaction (RT-PCR) analysis was performed, according to RT-PCR analysis, the nanoconjugates target virulence genes involved in C. albicans hyphae and biofilm formation. Nanoconjugates inhibited 25 % growth of human embryonic kidney (HEK) 293 cell line, indicating moderate cytotoxicity of active nanoconjugates in an in-vitro cytotoxicity study. Therefore, biogenic SeNPs conjugated with ginger dietary extract may be a potential antifungal agent and drug carrier for inhibiting C. albicans growth and biofilm formation.

Fungal Infections, Treatment and Antifungal Resistance: The Sub-Saharan African Context

Fungal pathogens cause a wide range of infections in humans, from superficial to disfiguring, allergic syndromes, and life-threatening invasive infections, affecting over a billion individuals globally. With an estimated 1.5 million deaths annually attributable to them, fungal pathogens are a major cause of mortality in humans, especially people with underlying immunosuppression. The continuous increase in the population of individuals at risk of fungal infections in sub-Saharan Africa, such as HIV patients, tuberculosis patients, intensive care patients, patients with haematological malignancies, transplant (haematopoietic stem cell and organ) recipients and the growing global threat of multidrug-resistant fungal strains, raise the need for an appreciation of the region's perspective on antifungal usage and resistance. In addition, the unavailability of recently introduced novel antifungal drugs in sub-Saharan Africa further calls for regular evaluation of resistance to antifungal agents in these settings. This is critical for ensuring appropriate and optimal use of the limited available arsenal to minimise antifungal resistance. This review, therefore, elaborates on the multifaceted nature of fungal resistance to the available antifungal drugs on the market and further provides insights into the prevalence of fungal infections and the use of antifungal agents in sub-Saharan Africa.