Tackling the emerging threat of antifungal resistance to human health

The sulfur-related metabolic status of Aspergillus fumigatus during infection reveals cytosolic serine hydroxymethyltransferase as a promising antifungal target

Sulfur metabolism is an essential aspect of fungal physiology and pathogenicity. Fungal sulfur metabolism comprises anabolic and catabolic routes that are not well conserved in mammals, therefore is considered a promising source of prospective novel antifungal targets. To gain insight into Aspergillus fumigatus sulfur-related metabolism during infection, we used a NanoString custom nCounter-TagSet and compared the expression of 68 key metabolic genes in different murine models of invasive pulmonary aspergillosis, at 3 time-points, and under a variety of in vitro conditions. We identified a set of 15 genes that were consistently expressed at higher levels in vivo than in vitro, suggesting that they may be particularly relevant for intrapulmonary growth and thus constitute promising drug targets. Indeed, the role of 5 of the 15 genes has previously been empirically validated, supporting the likelihood that the remaining candidates are relevant. In addition, the analysis of gene expression dynamics at early (16 h), mid (24 h), and late (72 h) time-points uncovered potential disease initiation and progression factors. We further characterized one of the identified genes, encoding the cytosolic serine hydroxymethyltransferase ShmB, and demonstrated that it is an essential gene of A. fumigatus, also required for virulence in a murine model of established pulmonary infection. We further showed that the structure of the ligand-binding pocket of the fungal enzyme differs significantly from its human counterpart, suggesting that specific inhibitors can be designed. Therefore, in vivo transcriptomics is a powerful tool for identifying genes crucial for fungal pathogenicity that may encode promising antifungal target candidates.

Rutin attenuates oxidative damage-induced renal injury in rats experimentally infected with Cryptococcus neoformans by improving antioxidant capacity and reducing fungal burden

Oxidative stress plays a pivotal role in the pathophysiology of infectious diseases, contributing to pathogenesis and the appearance of clinical symptoms. However, the involvement of oxidative stress in renal cryptococcosis remains unknown, as do the potential protective effects of rutin. Cryptococcus neoformans is considered the main agent of cryptococcosis, a systemic life-threatening opportunistic fungal disease that affects internal organs. In 2022, the World Health Organization classified it as a critical-priority group on its Fungal Priority Pathogens List. Rutin, a flavonoid with potent antioxidant and antifungal properties, has been proposed as a protective agent. Thus, this study aimed to evaluate whether 50 mg rutin/kg body weight prevents or reduces C. neoformans var. Grubii-induced renal oxidative stress. Renal fungal burden was significantly lower in rats that were treated with rutin and experimentally infected with C. neoformans, compared to those treated with saline solution and experimentally infected. Renal reactive oxygen species (ROS) and protein carbonylation levels were significantly higher in experimentally infected rats compared to uninfected controls, whereas catalase (CAT) and glutathione S-transferase (GST) activities were significantly lower. Treatment with rutin prevented the increase in renal ROS levels and the inhibition of CAT activity elicited by C. neoformans var. Grubii. However, no significant differences were observed in lipid damage or superoxide dismutase activity. This study is the first to demonstrate that C. neoformans var. Grubii infection induces renal oxidative damage in rats by promoting oxidative stress, increasing ROS levels, and impairing antioxidant defenses. Rutin treatment restored redox status in experimental rats through mechanisms involving oxidative stress. The protective effects of rutin against C. neoformans-induced kidney damage may result from its combined ability to scavenge ROS, inhibit protein damage, and enhance the antioxidant system.

Label-free rapid antimicrobial susceptibility testing with machine-learning based dynamic holographic laser speckle imaging

Antimicrobial resistance (AMR) presents a significant global challenge, creating an urgent need for rapid and sensitive antimicrobial susceptibility testing (AST) methods to guide timely treatment decisions. Traditional AST techniques, such as broth microdilution, disk diffusion, and gradient diffusion assays, require extended incubation times, delaying critical therapeutic interventions. In this study, we present a dynamic holographic laser speckle imaging (DhLSI) system, coupled with machine learning algorithms, for rapid assessment of bacterial susceptibility upon antibiotic treatment. Our method operates by utilizing a reference beam to enhance the detection of weak scattering signals, capable of performing AST at bacterial concentrations as low as 103 CFU/mL, while producing results consistent with those obtained using the standard concentration of 105 CFU/mL. By employing artificial neural networks (ANN) to analyze dynamic speckle patterns, the DhLSI system can determine bacterial susceptibility within 2-3 h. The system was validated using model Gram-positive and Gram-negative bacterial strains, as well as two antibiotic treatments with different mechanisms of action. Experiments conducted on bacteria incubated on different days demonstrated consistent performance. This approach offers a rapid, label-free platform for early-stage infection diagnosis and effective antimicrobial stewardship, with the potential to be implemented in clinical settings to address AMR challenges.

Targeting biofilm formation in Candida albicans with halogenated pyrrolopyrimidine derivatives

Growing concern over environmental contaminants, including pharmaceuticals and antifungal agents, highlights their role in promoting resistance and biofilm formation by microorganisms. Antifungal resistance, especially in drug-resistant Candida spp., poses a global threat, worsened by the widespread use of antifungal agents in both clinical applications and environmental contamination. This study investigates the antibiofilm properties of various halogenated pyrrolo pyrimidine derivatives, specifically 4-chloro-5-iodo-7H-pyrrolo[2,3-d]pyrimidine (10) and 2,4-dichloro-5-iodo-7H-pyrrolo[2,3-d]pyrimidine (16), against fluconazole-resistant C. albicans. Both compounds demonstrated strong biofilm inhibition, with 16 showing greater efficacy even at lower concentrations. qRT-PCR analysis revealed downregulation of key biofilm- and hyphae/germ tube-relating genes, including ALS3, HWP1, and ECE1, alongside upregulation of stress response and biofilm regulator genes such as CDR11, GST3, IFD6, UCF1, YWP1, and ZAP1, indicating complex regulatory responses to the treatments. Molecular docking analysis revealed that these compounds bind effectively to the binding cavity of the ALS3 protein, with halogen atoms playing a key role in stabilizing interaction. Compound 16 exhibited minimal cytotoxicity in Brassica rapa and Caenorhabditis elegans models, suggesting a favorable ADMET safety profile. Confocal microscopy analysis confirmed the compounds effectiveness in preventing biofilm formation when applied as biodegradable PLGA coatings on biomaterial surfaces. These findings suggest that 16 holds promise as a potent antifungal agent with reduced environmental impact, offering both efficacy and sustainability.

SidF, a dual substrate N5-acetyl-N5-hydroxy-L-ornithine transacetylase involved in Aspergillus fumigatus siderophore biosynthesis

Siderophore-mediated iron acquisition is essential for the virulence of Aspergillus fumigatus, a fungus causing life-threatening aspergillosis. Drugs targeting the siderophore biosynthetic pathway could help improve disease management. The transacetylases SidF and SidL generate intermediates for different siderophores in A. fumigatus. A. fumigatus has a yet unidentified transacetylase that complements SidL during iron deficiency in SidL-lacking mutants. We present the first X-ray structure of SidF, revealing a two-domain architecture with tetrameric assembly. The N-terminal domain contributes to protein solubility and oligomerization, while the C-terminal domain containing the GCN5-related N-acetyltransferase (GNAT) motif is crucial for the enzymatic activity and mediates oligomer formation. Notably, AlphaFold modelling demonstrates structural similarity between SidF and SidL. Enzymatic assays showed that SidF can utilize acetyl-CoA as a donor, previously thought to be a substrate of SidL but not SidF, and selectively uses N5-hydroxy-L-ornithine as an acceptor. This study elucidates the structure of SidF and reveals its role in siderophore biosynthesis. We propose SidF as the unknown transacetylase complementing SidL activity, highlighting its central role in A. fumigatus siderophore biosynthesis. Investigation of this uncharacterized GNAT protein enhances our understanding of fungal virulence and holds promise for its potential application in developing antifungal therapies.

Intrinsic Natural Resistance of Various Plant Pathogens to Ipflufenoquin, a New DHODH (Dihydroorotate Dehydrogenase)-Inhibiting Fungicide, in Relation to an Unaltered Amino Acid Sequence of the Target Site

In recent years, increasingly stringent pesticide regulations have made the development of new chemistries challenging. Under these regulations, the new fungicide ipflufenoquin (FRAC Code 52) was first released in Japan. Its mode of action is new; it inhibits dihydroorotate dehydrogenase (DHODH), a key enzyme in the biosynthesis of pyrimidine-based nucleotides. However, because it is a single-site inhibitor, the risk of resistance developing in pathogens must be carefully considered. The risk for dual use of DHODH inhibitors in agriculture and medicine has also become a great concern because a new antifungal olorofim is under development against human pathogens now, and cross-resistance has recently been reported between ipflufenoquin and olorofim in Aspergillus fumigatus. In this study, the sensitivity to ipflufenoquin was examined in culture and in plants using "baseline" isolates, which had never been exposed to DHODH inhibitors. Isolates of Alternaria alternata, Botrytis cinerea, B. elliptica, Colletotrichum fioriniae, C. fructicola, C. nymphaeae, C. orbiculare, C. siamense, C. tropicale, C. truncatum, and Sclerotinia sclerotiorum were highly sensitive to ipflufenoquin in culture, but isolates of Coniella vitis, Corynespora cassiicola, Pseudocercospora fuligena, and Rhizoctonia solani were inherently resistant. Ipflufenoquin had low efficacy against C. cassiicola and C. vitis after inoculation of cucumber and grapevine leaves, respectively. To understand the mechanism of natural resistance, we analyzed the partial sequence of pyrE genes, which encode the DHODH enzyme, but did not find any differences in the deduced amino acids that were thought to be associated with resistance. Thus, mechanisms other than target-site mutations might be involved in the intrinsic resistance.

Chemical Innovations of Antimicrobial Polymers for Combating Antimicrobial Resistance

The global rise of antimicrobial resistance (AMR) has rendered many traditional antibiotics ineffective, leading to an urgent need for alternative therapeutic strategies. Antimicrobial polymers, with their ability to rapidly kill bacteria by disrupting or crossing membranes and/or targeting multiple microbial functions without inducing resistance, offer a promising solution. This perspective explores recent innovations in the design and synthesis of antimicrobial polymers, focusing on their chemical motifs, structural derivatives, and their applications in combating systemic and topical infections. We also highlight key challenges in translating these materials from laboratory research to clinical practice, including issues related to the high dose required, bioavailability and stability in systemic infection treatment, and ability to disperse and kill biofilms in localized infection management. By addressing these challenges, antimicrobial polymers could play a crucial role in the development of next-generation therapeutics to combat multidrug-resistant pathogens. This perspective attempts to summarize significant insights for the design and development of advanced antimicrobial polymers to overcome AMR, offering potential pathways to improve clinical outcomes in treating systemic and local infections.

The Impact of Dietary Interventions on the Pharmacokinetics of Antifungal Drugs: A Systematic Review with Meta-analyses

BACKGROUND AND OBJECTIVE

Managing food-drug interactions may help to optimize the efficacy and safety of antifungal therapy. This systematic review followed Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines to evaluate how food, beverages, antacids, and mineral supplements influence the pharmacokinetic (PK) parameters or pharmacokinetic/pharmacodynamic (PK/PD) indices of 14 orally administered antifungal drugs.

METHODS

We considered all studies evaluating the effects of food, beverages, antacids, and mineral supplements on PK parameters and PK/PD indices of oral antifungal drugs for inclusion. We excluded in vitro, in silico, animal studies, reviews, and alcohol-related investigations. Searches were conducted in Medline (via PubMed), Embase, and Cochrane Library from database inception to June 2024. We evaluated the risk of bias using the National Institutes of Health (NIH) tool for before-after studies and the Cochrane tool for parallel and cross-over trials. We performed meta-analyses when two or more studies with comparable designs were available; otherwise, results were summarized qualitatively.

RESULTS

The review included 73 studies from 68 reports. Only studies investigating the effect of dietary interactions on PK parameters were found. Meta-analyses were conducted for seven antifungal drugs, while qualitative synthesis covered the remaining drugs. Open-label, cross-over studies accounted for 58% of trials, aligning with Food and Drug Administration (FDA) recommendations. A high risk of bias appeared in 33% of studies, while only 7% showed low risk. Among 11 antifungals with food-effect data, seven (64%) exhibited clinically important interactions. High positive food effects (area under the concentration-time curve (AUC) or peak serum concentration (Cmax) increased by > 45%) were seen for griseofulvin, itraconazole capsules and tablets (except rice-based meals), and posaconazole immediate-release tablets and suspension. A moderate positive impact of high-fat meals (AUC or Cmax increased in the range of 35-45%) occurred for ibrexafungerp and oteseconazole. A high negative food effect was observed on the absorption of voriconazole and itraconazole oral suspension or super bioavailable (SUBA) capsules (AUC or Cmax decreased by > 40%). Antacids strongly reduced itraconazole and ketoconazole absorption, while nutritional supplements improved posaconazole bioavailability. Acidic beverages such as Coca Cola substantially enhanced the absorption of itraconazole, ketoconazole, and posaconazole, whereas orange juice significantly reduced itraconazole bioavailability.

CONCLUSION

Interactions were influenced by such factors as drug physicochemical properties, type of dietary intervention, drug formulation, and patient characteristics. Although the review largely filled the existing gaps in recommendations, we judged the overall quality of evidence as low owing to outdated studies, methodological inconsistencies, and uneven data availability. Further research involving PK/PD indices is needed to link the postprandial changes in the bioavailability of antifungal drugs with their clinical efficacy.

OTHER

The protocol of the systematic review was registered in March 2024 in the Open Science Framework (OSF) Registries ( https://doi.org/10.17605/OSF.IO/HAVK9 ).

Rational search for natural antimicrobial compounds: relevance of sesquiterpene lactones

Antimicrobial resistance is one of the most pressing global health challenges, as many pathogens are rapidly evolving to evade existing treatments. Despite this urgent need for new solutions, natural plant-derived compounds remain relatively underexplored in the development of antimicrobial drugs. This report highlights an innovative approach to discovering potent antimicrobial agents through bioguided fractionation of numerous plant species from the rich Argentinean flora. By systematically screening 60 species (over 177 extracts) for antimicrobial activity against representative strains of gram-positive and gram-negative bacteria, we identified promising bioactive compounds within the Asteraceae family-particularly sesquiterpene lactones from the Xanthium genus. Building on this basis, we synthesized semi-synthetic derivatives by chemically modifying plant sub-extracts, focusing on structures incorporating heteroatoms and/or heterocycles containing oxygen and nitrogen (important for the bioavailability and bioactivity that they are capable of providing). These modifications were evaluated for their potential to enhance antimicrobial efficacy against bacteria and Candida species, including resistant strains. Our findings suggest that tailoring natural metabolites from Xanthium and related Asteraceae species can significantly improve their antimicrobial properties. This strategy offers a promising pathway for the development of novel therapeutic agents to combat bacterial and fungal infections in an era of rising drug resistance.

A novel pan-fungal screening platform for antifungal drug discovery: proof of principle study

Broad-spectrum activity is a desirable property of novel antifungal drugs, but relevant in vitro testing is complicated by differential nutritional requirements and growth dynamics of fungal pathogens. Many screens for novel drugs are initiated against individual species or genera, with hit compounds later tested for "pan-fungal" activity. Hypothesizing that an optimized pan-fungal methodology would enhance the efficiency of early-stage drug discovery, a standardized assay was developed for a selection of World Health Organization-defined critical and high-priority fungal pathogens. Instead of using the standard susceptibility testing broth RPMI, an enriched media "fungal RPMI" (fRPMI), including multiple additional fungal growth-enhancing nutrients, was utilized. To assess utility for pan-fungal growth assessments, growth in fRPMI was compared to RPMI medium for 12 fungal pathogens. Growth was significantly improved in 7/12 species in fRPMI after 24 and/or 48 hours. For our proof-of-principle study, 500 chemical fragments from the Maybridge Ro3 Fragment library were screened at concentrations of 0.1 or 1 mM against five fungal pathogens: Aspergillus fumigatus, Candida albicans, Candida auris, Cryptococcus neoformans, and Nakaseomyces glabratus. Assay quality was assessed using z-factor analysis, and hits were normalized using a standard z-score to identify outliers. All assays achieved a high-quality z-factor (≥0.5) with readings at ≤24 hours, allowing the identification of 23 compounds with antifungal activity against at least one fungal species. From these, five compounds were identified as having pan-assay interference or broadly toxic properties. In conclusion, hits identified from pan-fungal phenotypic growth-based assays demonstrate reproducibility in all fungal species tested with carefully optimized conditions and precise timing.

Proton-Detected Solid-State NMR for Deciphering Structural Polymorphism and Dynamic Heterogeneity of Cellular Carbohydrates in Pathogenic Fungi

Carbohydrate polymers in their cellular context display highly polymorphic structures and dynamics essential to their diverse functions, yet they are challenging to analyze biochemically. Proton-detection solid-state NMR spectroscopy offers high isotopic abundance and sensitivity, enabling the rapid and high-resolution structural characterization of biomolecules. Here, an array of 2D/3D 1H-detection solid-state NMR techniques are tailored to investigate polysaccharides in fully protonated or partially deuterated cells of three prevalent pathogenic fungi: Rhizopus delemar, Aspergillus fumigatus, and Candida albicans, representing filamentous species and yeast forms. Selective detection of acetylated carbohydrates reveals 15 forms of N-acetylglucosamine units in R. delemar chitin, which coexists with chitosan, and associates with proteins only at limited sites. This is supported by distinct order parameters and effective correlation times of their motions, analyzed through relaxation measurements and model-free analysis. Five forms of α-1,3-glucan with distinct structural origins and dynamics were identified in A. fumigatus, important for this buffering polysaccharide to perform diverse roles of supporting wall mechanics and regenerating a soft matrix under antifungal stress. Eight α-1,2-mannan side chain variants in C. albicans were resolved, highlighting the crucial role of mannan side chains in maintaining interactions with other cell wall polymers to preserve structural integrity. These methodologies provide novel insights into the functional structures of key fungal polysaccharides and create new opportunities for exploring carbohydrate biosynthesis and modifications across diverse organisms.

Synthesis, characterization, and microbiological evaluation of new triazolopyrimidine-based ferrocenes as potent antimicrobial prospects

Antimicrobial metallodrugs have gained considerable attention for their potent inhibitory activity and clinical success, driving the development of novel metallodrug candidates. These efforts have uncovered new bioactive scaffolds and mechanisms of action. However, the global challenge of antimicrobial resistance (AMR), fueled by the genetic adaptability of microbes and resistance to nearly all antibiotic classes, highlights the urgent need for innovative antibiotics. In this study, we expand the repertoire of metallodrugs by designing, synthesizing, and biologically evaluating triazolopyrimidine-based ferrocenes as antimicrobial agents. These compounds demonstrated broad-spectrum activity against both bacterial and fungal pathogens. Advanced characterization techniques, including NMR, HRMS, FE-SEM, and SCXRD, confirmed their structural integrity and properties. Notably, the ferrocenes exhibited potent antifungal activity against Candida species, comparable to fluconazole, and were effective against Escherichia coli and Staphylococcus aureus. Our findings reveal a new class of metallodrugs with significant antimicrobial potential, offering promising avenues to combat AMR in future.

Aspergillus fumigatus biology, immunopathogenicity and drug resistance

Aspergillus fumigatus is a saprophytic fungus prevalent in the environment and capable of causing severe invasive infection in humans. This organism can use strategies such as molecule masking, immune response manipulation and gene expression alteration to evade host defences. Understanding these mechanisms is essential for developing effective diagnostics and therapies to improve patient outcomes in Aspergillus-related diseases. In this Review, we explore the biology and pathogenesis of A. fumigatus in the context of host biology and disease, highlighting virus-associated pulmonary aspergillosis, a newly identified condition that arises in patients with severe pulmonary viral infections. In the post-pandemic landscape, in which immunotherapy is gaining attention for managing severe infections, we examine the host immune responses that are critical for controlling invasive aspergillosis and how A. fumigatus circumvents these defences. Additionally, we address the emerging issue of azole resistance in A. fumigatus, emphasizing the urgent need for greater understanding in an era marked by increasing antimicrobial resistance. This Review provides timely insights necessary for developing new immunotherapeutic strategies against invasive aspergillosis.

Regulating Intratumoral Fungi With Hydrogels: A Novel Approach to Modulating the Tumor Microbiome for Cancer Therapy

BACKGROUND

Fungi in tumors act as a double-edged sword, potentially worsening or alleviating malignancy based on the ecological balance within the tumor microenvironment (TME). Hydrogels, as innovative drug delivery systems, are poised to redefine treatment paradigms. As advanced biomaterials, they offer a versatile platform for encapsulating and releasing antifungal agents and immunomodulators, responding to the TME's unique demands.

METHODS

We have conducted and collated numerous relevant reviews and studies in recent years from three aspects: Hydrogels, intra-tumoral fungi, and tumor microbe microenvironment, in the hope of identifying the connections between hydrogels and intra-tumoral microbes.

RESULTS

This review underscores the crucial role of intra-tumoral microbes, particularly fungi, in tumorigenesis, progression, and treatment efficacy. At the same time, we concentrated on the findings of hydrogels investigations, with their remarkable adaptability to the tumor microenvironment emerge as intelligent drug delivery systems.

CONCLUSIONS

Hydrogels unique ability to precisely target and modulate the tumor microflora, including fungi, endows them with a significant edge in enhancing treatment efficacy. This innovative approach not only holds great promise for improving cancer therapy outcomes but also paves the way for developing novel strategies to control metastasis and prevent cancer recurrence.

Doubling of triazole resistance rates in invasive aspergillosis over a 10-year period, Belgium, 1 April 2022 to 31 March 2023

BackgroundDutch national treatment guidelines for fungal infections have been adapted based on surveillance findings of triazole resistance rates >10% in Aspergillus species isolates. In Belgium, nationwide resistance data have not been collected since 2011.AimOur objective was to evaluate changes in antifungal susceptibility among Aspergillus species isolates from patients with invasive aspergillosis.MethodsLaboratories across Belgium were invited to send all clinically relevant Aspergillus species isolates from patients diagnosed with invasive aspergillosis, collected between April 2022 and March 2023, to the National Reference Centre for Mycosis at UZ Leuven for identification and antifungal susceptibility testing.ResultsOverall, 29 clinical laboratories contributed 309 isolates from 297 patients. Median patient age was 66 years (range: 6 months-96 years). Among isolates, 61% (189/309) were from male patients. At species level, Aspergillus fumigatus isolates predominated (278/309, 90%), with a 9.7% (27/278) triazole resistance rate, compared to the 4.6% rate found in 2011. Of 27 resistant isolates, successful Cyp51A sequencing of 26 showed 20 with the TR34/L98H resistance mechanism. Across the country, local A. fumigatus triazole resistance rates varied. Among provinces in the Flanders region, Antwerp had the highest resistance rate (15.4%: 10/65; p = 0.082), Flemish Brabant (6/48) also had a rate >10%, while Limburg (2/46) had the lowest rate.ConclusionsGeographical differences in A. fumigatus triazole resistance rates stress the importance of implementing broad prospective surveillance initiatives, not limited to one region or one hospital. In Belgium, triazole resistance rates have doubled over 10 years, nearly attaining the 10% threshold, warranting re-evaluation of local empirical antifungal treatment regimen decisions.

Antifungal susceptibility of a collection of Aspergillus fumigatus strains isolated from patients with invasive pulmonary aspergillosis and COVID-19 associated aspergillosis

We assessed the antifungal susceptibility of 86 Aspergillus fumigatus strains by a phenotypic test. Azole sensitivity was compared to a molecular test detecting cyp51A mutations. Azole resistance was quite limited, whereas strains from COVID-19 patients showed higher amphotericin B MICs. The molecular test showed a 100 %-agreement with the phenotypic assay.

Uncovering the role of mitochondrial genome in pathogenicity and drug resistance in pathogenic fungi

Fungal infections are becoming more prevalent globally, particularly affecting immunocompromised populations, such as people living with HIV, organ transplant recipients and those on immunomodulatory therapy. Globally, approximately 6.55 million people are affected by invasive fungal infections annually, leading to serious health consequences and death. Mitochondria are membrane-bound organelles found in almost all eukaryotic cells and play an important role in cellular metabolism and energy production, including pathogenic fungi. These organelles possess their own genome, the mitochondrial genome, which is usually circular and encodes proteins essential for energy production. Variation and evolutionary adaptation within and between species' mitochondrial genomes can affect mitochondrial function, and consequently cellular energy production and metabolic activity, which may contribute to pathogenicity and drug resistance in certain fungal species. This review explores the link between the mitochondrial genome and mechanisms of fungal pathogenicity and drug resistance, with a particular focus on Cryptococcus neoformans and Candida albicans. These insights deepen our understanding of fungal biology and may provide new avenues for developing innovative therapeutic strategies.

The unfolded protein response is a potential therapeutic target in pathogenic fungi

Pathogenic fungal infections cause significant morbidity and mortality, particularly in immunocompromised patients. The frequent emergence of multidrug-resistant strains challenges existing antifungal therapies, driving the need to investigate novel antifungal agents that target new molecular moieties. Pathogenic fungi are subjected to various environmental stressors, including pH, temperature, and pharmacological agents, both in natural habitats and the host body. These stressors elevate the risk of misfolded or unfolded protein production within the endoplasmic reticulum (ER) which, if not promptly mitigated, can lead to the accumulation of these proteins in the ER lumen. This accumulation triggers an ER stress response, potentially jeopardizing fungal survival. The unfolded protein response (UPR) is a critical cellular defense mechanism activated by ER stress to restore the homeostasis of protein folding. In recent years, the regulatory role of the UPR in pathogenic fungi has garnered significant attention, particularly for its involvement in fungal adaptation, regulation of virulence, and drug resistance. In this review, we comparatively analyze the UPRs of fungi and mammals and examine the potential utility of the UPR as a molecular antifungal target in pathogenic fungi. By clarifying the specificity and regulatory functions of the UPR in pathogenic fungi, we highlight new avenues for identifying potential therapeutic targets for antifungal treatments.

Characterizing the Soil Microbial Community Associated with the Fungal Pathogen Coccidioides immitis

Coccidioidomycosis is a fungal disease affecting humans and other mammals caused by environmental pathogens of the genus Coccidioides. Human exposure to the pathogen occurs via inhalation of spores aerosolized from soil. Thus, understanding the ecological factors that shape the distribution of Coccidioides in soils is important for minimizing the risk of human exposure, though this task remains challenging due to the pathogen's highly variable spatial distribution. Here, we examined the associations between the soil microbial community and Coccidioides immitis' presence within the Carrizo Plain National Monument, a minimally disturbed grassland ecosystem, and the site of a longitudinal study examining the effects of rodents and their burrows on C. immitis' presence in soils. Using internal transcribed spacer 2 (ITS2) and 16S amplicon sequencing to characterize the soil fungal and bacterial communities, we found over 30 fungal species, including several other members of the Onygenales order, that co-occurred with C. immitis more frequently than would be expected by chance. Coccidioides-positive samples were significantly higher in fungal and bacterial diversity than negative samples, an association partly driven by higher Coccidioides presence within rodent burrows compared to surface soils. Soil source (i.e., rodent burrow versus surface soil) explained the largest amount of variation in bacterial and fungal community diversity and composition, with soils collected from rodent burrows having higher fungal and bacterial diversity than those collected from adjacent surface soils. While prior evidence is mixed regarding the relationship between the presence of Coccidioides and microbial diversity, we find that favorable microhabitats, such as rodent burrows, lead to a positive association between soil microbial diversity and Coccidioides presence, particularly in otherwise resource-limited natural environments.

The endophytic fungus Cosmosporella sp. VM-42 from Vinca minor is a source of bioactive compounds with potent activity against drug-resistant bacteria

Medicinal plants serve as valuable resources for the isolation of endophytic fungi. Vinca minor is a well-known producer of important vinca alkaloids and emerges as a promising source of endophytic fungi with antibacterial potential and biosynthetic capacity. In this study, we isolated an endophytic fungus from V. minor and identified it as Cosmosporella sp. VM-42. To date, relatively little is known about this fungal genus. The ethyl acetate extract of this isolate selectively inhibited Gram-positive bacteria, such as methicillin-sensitive and methicillin-resistant Staphylococcus aureus (MSSA and MRSA). Therefore, we isolated the most abundant compound from the crude extract and identified it as nectriapyrone with MIC and MBC values ranging from 125 to 62.5 µg/mL against MSSA and MRSA strains. We further sequenced and annotated the 39.07 Mb genome of the isolate, revealing that it encodes 9842 protein-coding genes, including 415 genes for carbohydrate-active enzymes and various biosynthetic gene clusters. Our untargeted metabolomic analysis shows that the fungus produces various secondary metabolites, including cyclodepsipeptides, dimeric naphtho-γ-pyrones, and macrolactones, which are known to have antifungal and antibacterial activities. In addition, we used small-molecule epigenetic modulators to activate the expression of silent biosynthetic gene clusters to broaden the chemical profile of Cosmosporella sp. VM-42. Taken together, we provide a first systematic analysis of Cosmosporella sp. VM-42, and our results show that it is a promising source of compounds with pharmacological potential against drug resistant bacteria.

Synthesis of a New Purine Analogue Class with Antifungal Activity and Improved Potency against Fungal IP3-4K

New antifungals are urgently needed to treat deadly fungal infections. Targeting the fungal inositol polyphosphate kinases IP3-4K (Arg1) and IP6K (Kcs1) is a promising strategy as it has been validated genetically to be crucial for fungal virulence but never pharmacologically. We now report the synthesis of DT-23, an analogue of N2-(m-trifluorobenzylamino)-N6-(p-nitrobenzylamino)purine (TNP), and demonstrate that it more potently inhibits recombinant Arg1 from the priority pathogen Cryptococcus neoformans (Cn) (IC50 = 0.6 μM) than previous analogues (IC50 = 10-30 μM). DT-23 also inhibits recombinant Kcs1 with similar potency (IC50 = 0.68 μM) and Arg1 and Kcs1 activity in vivo. Unlike previous analogues, DT-23 inhibits fungal growth (MIC50 = 15 μg/mL) and only 1.5 μg/mL synergizes with Amphotericin B to kill Cn in vitro. DT-23/Amphotericin B is also more protective against Cn infection in an insect model compared to each drug alone. Transcription profiling shows that DT-23 impacts early stages in IP synthesis and cellular functions impacted by IPK gene deletion, consistent with its targeted effect. This study establishes the first pharmacological link between inhibiting IPK activity and antifungal activity, providing tools for studying IPK function and a foundation to potentially develop a new class of antifungal drug.

Antifungal resistance in yeasts from One Health perspective: A Brazilian study

Environmental exposure to fungicides can induce cross-resistance in filamentous fungi, but little is known about their effects on medically important yeasts. This multicenter study investigated the resistance in Candida isolated from different sources and evaluated the influence of clinical and environmental antifungals. Different yeasts were collected from patients, hospital environments, swine, poultry and their surroundings in four different states of Brazil. A total of 571 isolates were identified, of which 82.5 % belonged to the genus Candida. Antifungal susceptibility testing revealed that C. tropicalis had the highest resistance rate (12 %) to fluconazole, followed by C. glabrata and C. albicans with resistance rates of 8 % and 6 %, respectively. Resistance to micafungin was most common in C. glabrata (15 %). For amphotericin B, we identified two non-wild-type isolates, one belonging to the C. tropicalis species and the other to C. glabrata. Most resistant isolates were recovered from patients; however, resistance was also observed in animal and environmental isolates. In addition, susceptibility to tebuconazole, an environmental azole, was evaluated and a cut-off value of 8 μg/mL was proposed to assess potential resistance. Among the isolates, 10.5 % had a high minimum inhibitory concentrations (MIC) for tebuconazole. Moreover, cross-resistance is possible to occur, as 3.6 % of Candida isolates were resistant to fluconazole and had high MIC for tebuconazole, particularly C. albicans, C. tropicalis, and C. krusei. This study demonstrates the importance of monitoring yeast resistance to antifungals and environmental fungicides in different niches, and calls for a multidisciplinary approach to understand multiple factors involved in resistance development.

How does antifungal resistance vary in Candida (Candidozyma) auris and its clades? Quantitative and qualitative analyses and their clinical implications

BACKGROUND

Candida (Candidozyma) auris is a multidrug-resistant yeast that emerged as a significant health care-associated pathogen. It is classified as an urgent threat to public health due to the high resistance to available antifungal agents. Globally six distinct clades of C. auris have been identified with varying antifungal susceptibility patterns and geographical distributions.

OBJECTIVES

The aim of this review is to investigate the (published) antifungal susceptibility profiles of different C. auris clades to identify those with a higher prevalence of resistance.

SOURCES

A comprehensive literature review was conducted using PubMed, SciELO, Google Scholar, and MEDLINE databases to collect data on MIC distributions and clade designations of C. auris strains.

CONTENT

A total of 1031 C. auris strains were included. Clades I and III, which are closely related phylogenetically, displayed the highest resistance rates, particularly to fluconazole, with 94% and 96% of isolates, respectively. Clade IV also exhibited resistance to both azoles and echinocandins. In contrast, clades II, V, and VI had lower resistance rates, with clade VI being entirely susceptible to fluconazole. Anidulafungin demonstrated the greatest efficacy across all clades, with resistance rates ranging from 0% to 3.67%. Furthermore, clades V and VI showed complete susceptibility to all antifungal agents evaluated.

IMPLICATIONS

This study highlights significant variations in antifungal resistance profiles across the six C. auris clades. Clades I, III, and IV stand out because of their multidrug resistance, particularly to fluconazole and amphotericin B, posing serious challenges for treatment. Continuous global surveillance and tailored management strategies are essential for controlling C. auris infections, especially in highly resistant clades. Enhanced diagnostic capabilities and further genomic studies are critical to understanding the evolving nature of resistance in this emerging pathogen and improving therapeutic outcomes. Clade-specific antifungal resistance in C. auris requires monitoring to optimize therapy selection during outbreaks.

Nanoparticle-based antifungal therapies innovations mechanisms and future prospects

Fungal infections present an increasing global health challenge, with a substantial annual mortality rate of 1.6 million deaths each year in certain situations. The emergence of antifungal resistance has further complicated treatment strategies, underscoring the urgent need for novel therapeutic approaches. This review explores recent advances in nanoparticle-based therapies targeting fungal infections, emphasizing their unique potential to enhance drug solubility, bioavailability, and targeted delivery. Nanoparticles offer the ability to penetrate biological barriers, improve drug stability, and act as direct antifungal agents by disrupting fungal cell walls and generating reactive oxygen species. Despite their promising applications, challenges such as potential toxicity, scalability of production, and the need for controlled drug release remain. Future research should focus on optimizing nanoparticle properties, evaluating long-term safety profiles, developing environmentally sustainable synthesis methods, and exploring synergistic approaches with existing antifungal drugs. Nanotechnology offers a transformative opportunity in the management of fungal diseases, paving the way for more effective and targeted treatments.

Organoselenium compounds as an enriched source for the discovery of new antimicrobial agents

The urgent need for novel antifungal drugs is underscored by the limited number of antifungal agents in clinical development and the global spread of fungal resistance. This study highlights the potential of organoselenium compounds as a new source of scaffolds with promising antifungal activity against a variety of fungal strains. Analysis of over 300 000 compounds screened by the Community for Open Antimicrobial Drug Discovery (CO-ADD) for antibacterial and antifungal activity identified 233 organoselenium derivatives. A remarkable 33% (77) of these exhibited antifungal activity against two representative strains of Candida and Cryptococcus, in contrast to only 2% of the non-selenium-containing organic compounds tested by CO-ADD. Of these compounds that displayed antifungal activity (MIC < 16 μg mL-1), 87% did not exhibit cytotoxicity against mammalian cell lines or haemolytic properties at similar concentrations, compared to only 35% of the organic 'hits'. A subset of these 69 compounds was further evaluated against three clinically relevant fungal strains that often exhibit resistance to current antifungals (Candida auris, MDR Candida auris, and Cryptococcus deuterogattii), and generally retained good activity. Lastly, we compared a handful of matched sulfur and selenium compounds which further highlighted the beneficial impact of this bioisosteric conversion on antifungal activity.

Synthesis of 2-Amino-4, 5-Diarylthiazole Derivatives and Evaluation of Their Anti-Candida Albicans Activity

The thiazole heterocycle is one of the most common moieties found in various drugs. Using 2-aminothiazole as the core structure, the amino group was functionalized with an amide. As a result, 30 trisubstituted 2-amino-4, 5-diarylthiazole derivatives were synthesized, with different substitutions introduced at the C2, C4, and C5 positions. The anti-Candida albicans biological activities of these synthetic compounds on five kinds of Candida albicans at different concentrations were detected by the microdilution method. In the first round, four derivatives of 2-amino-4, 5-diarylthiazole exhibited moderate anti-Candida albicans activity. Among them, 4a8 was chosen to be subjected to a demethylation process. Thus, 5a8 was synthesized successfully, giving anti-Candida albicans activity (MIC80 = 9 μM) similar to that of a typical antifungal drug, fluconazole. To understand the mechanism of anti-Candida albicans, molecular docking of the most active 5a8 against four target proteins of anti-Candida albicans, such as glutamine-fructose-6-phosphoamidamitransferase (GFAT), protein kinase (Yck2), heat-shock protein 90 (Hsp90), and lanosterol 14a-demethylase (CYP51) was carried out. Our research will provide an experimental basis and theoretical guidance for the further design of a new aminothiazole-leading pharmaceutical molecule.

Establishment of epidemiological cutoff values for Fonsecaea pedrosoi, the primary etiologic agent of chromoblastomycosis, and eight antifungal medications

Chromoblastomycosis, a fungal neglected tropical disease, is acquired through traumatic inoculation and is clinically characterized by a chronic granulomatous infection of the skin and subcutaneous tissue. Fonsecaea pedrosoi is the most commonly reported etiologic agent globally. Itraconazole is considered first-line therapy, but successful treatment with terbinafine, voriconazole, and posaconazole has been reported. F. pedrosoi minimum inhibitory concentration (MIC) data are limited, and epidemiological cutoffs (ECVs) are lacking; such data are important to help monitor antifungal resistance trends and guide initial antifungal selection. Thus, we performed antifungal susceptibility testing (AFST) on F. pedrosoi isolates and determined the MIC distributions and ECVs. AFST on Fonsecaea pedrosoi isolates was conducted at six laboratories from October 2023 to June 2024. Species identification was previously confirmed by DNA sequence analysis. AFST was performed by CLSI M38 standard broth microdilution method for itraconazole, voriconazole, posaconazole, isavuconazole, ketoconazole, terbinafine, flucytosine, and amphotericin B. The ECVs were established using the iterative statistical method with ECOFFinder (version 2.1) following CLSI M57 guidelines. We analyzed MIC results from 148 Fonsecaea pedrosoi isolates. The calculated ECVs were itraconazole, 0.5 µg/mL; voriconazole, 0.5 µg/mL; posaconazole, 0.5 µg/mL; isavuconazole, 1 µg/mL; ketoconazole, bimodal, no ECV determined; terbinafine, 0.25 µg/mL; flucytosine, rejected; and amphotericin, 8 µg/mL. These Fonsecaea pedrosoi ECVs, obtained through a multicenter international effort, provide a baseline to better understand the in vitro antifungal susceptibility profile of this species and monitor resistance. Clinicians and researchers can use these values to detect non-wild-type isolates with reduced susceptibility, reevaluate therapeutic options, and investigate potential clinical resistance if treatment failure occurs.IMPORTANCEChromoblastomycosis is a neglected tropical disease caused by an environmental, dematiaceous fungus. This fungal disease is acquired after a break in the skin that allows the fungus to enter, leading to a chronic infection in the skin and subcutaneous tissue. It is difficult to treat and often requires years of antifungal treatment. Fonsecaea pedrosoi is the most reported causative agent globally. Limited antifungal susceptibility data exist for F. pedrosoi making interpreting minimum inhibitory concentration (MIC) results difficult. We performed antifungal susceptibility testing on 148 F. pedrosoi isolates to establish MIC distributions and epidemiologic cutoff values (ECVs) for eight antifungals, including those commonly used to treat chromoblastomycosis. The calculated ECVs for the commonly used antifungals itraconazole and terbinafine were 0.5 and 0.25 µg/mL, respectively. ECVs can be helpful in choosing potential treatment options for F. pedrosoi and monitoring antifungal resistance epidemiology.

Induction of Antifungal Tolerance Reveals Genetic and Phenotypic Changes in Candida glabrata

Candida glabrata is an opportunistic, pathogenic fungus that is increasingly isolated from hospitalized patients. The incidence of drug tolerance, heteroresistance, and resistance is on the rise due to an overuse of antifungal drugs. The aim of this study was to expose a sensitive C. glabrata strain to sequentially increasing concentrations of two antifungal drugs, fluconazole, an azole that targets ergosterol biosynthesis, or caspofungin, an echinocandin that targets cell wall glucan synthesis. Analysis of the drug-exposed isolates showed development of antifungal tolerance, chromosomal abnormalities, decreased adhesion, attenuated virulence, and an increase in efflux pump activity. Furthermore, whole genome sequencing of all isolates exposed to different concentrations of fluconazole or caspofungin was performed to determine mutations in key genes that could correlate with the observed phenotypes. Mutations were found in genes implicated in adhesion, such as in the AWP, PWP, and EPA family of genes. Isolates exposed to higher drug concentrations displayed more mutations than those at lower concentrations.

Fungal Pulmonary Coinfections in COVID-19: Microbiological Assessment, Inflammatory Profiles, and Clinical Outcomes

Background and Objectives: Secondary pulmonary fungal infections in coronavirus disease 2019 (COVID-19) remain underexplored despite emerging reports linking them to heightened morbidity. Comorbidities, steroid use, and prolonged hospital stays can predispose patients to opportunistic fungi. This study aimed to evaluate the impact of fungal coinfection on inflammatory markers, disease severity, antifungal resistance profiles, and outcomes in hospitalized COVID-19 patients. Methods: This retrospective observational study enrolled 280 adults (≥18 years) with real-time polymerase chain reaction (RT-PCR)-confirmed COVID-19 admitted to a tertiary care center (January 2023-December 2024). Patients were divided into a COVID-19-only group (n = 216) and a COVID-fungal group (n = 64) based on bronchoalveolar lavage, sputum, and/or blood culture positivity for fungal pathogens. Inflammatory markers (C-reactive protein (CRP), procalcitonin, the neutrophil-to-lymphocyte ratio, and the systemic immune inflammation index) and severity scores (Acute Physiology and Chronic Health Evaluation II, CURB-65 score, and the National Early Warning Score) were measured. We assessed antifungal susceptibilities and recorded ICU admissions, ventilation, hospital length of stay, and mortality. Results:Aspergillus fumigatus (31.3%), Candida albicans (28.1%), Cryptococcus neoformans (7.8%), Pneumocystis jirovecii (6.3%), and Mucorales (6.3%) dominated; Candida glabrata, Candida tropicalis, and mixed infections were also noted. Multidrug-resistant (MDR) isolates or resistance to triazoles occurred in 25.0% of cultures. The COVID-19-fungal group showed significantly higher CRP (85.7 vs. 71.6 mg/L, p < 0.001), procalcitonin (2.4 vs. 1.3 ng/mL, p < 0.001), and APACHE II scores (18.6 vs. 14.8, p < 0.001). intensive-care unit admissions (39.1% vs. 19.9%, p = 0.004) and mechanical ventilation (26.6% vs. 10.2%, p = 0.01) were more frequent with fungal coinfection. Mortality trended at a higher rate (15.6% vs. 7.4%, p = 0.06). Conclusions: Pulmonary fungal coinfections intensify the inflammatory milieu, elevate severity scores, and lead to more frequent ICU-level interventions in COVID-19 patients. Early identification, guided by culture-based and molecular diagnostics, alongside prompt antifungal therapy, could mitigate adverse outcomes. These findings underscore the critical need for proactive fungal surveillance and rigorous stewardship in managing severe COVID-19 pneumonia.

Study on antifungal usage in patients with vaginal itching and discharge at a private hospital in Kolkata using the National Accreditation Board for Hospitals and Healthcare Providers and the World Health Organization prescribing criteria

Introduction

One in every 10 women presents with abnormal vaginal discharge in Gynaecology and Obstetrics Department, with the most common cause being candidiasis. Irrational use of antifungal for treatment of this condition leads to antifungal resistance and increase morbidity.

Materials and Methods

This retrospective study was conducted at the Department of Pharmacology in collaboration of Department of Obstetrics and Gynaecology of the private medical college hospital in Kolkata. One hundred and forty outpatient department prescriptions were screened and included in this study from March 2024 to April 2024, and the prescriptions of the previous 6 months were collected.

Results

The average number of drugs per prescription was 1.1. Antifungals were prescribed in 89.3%, out of which only 8.6% were in accordance with the standard treatment guidelines of management of vaginal candidiasis. The dose of the drug was written in 11.5% of the prescriptions while the duration of treatment was written in 84.9% of the prescriptions. The fungal culture and sensitivity testing was documented in only 10.7% of the prescriptions. 29.5% of the prescriptions had the generic name of the medicines whereas the complete diagnosis was written in only 13.7% of the prescriptions.

Conclusion

This study highlights the commonly encountered errors in prescribing of antifungal drugs in a tertiary care teaching hospital. These errors may lead to irrational prescribing of antifungal and development of antifungal resistance in the long run. Active surveillance in the form of regular prescription audit and organizing regular training workshop for the prescribers will improve the prescribing practice.

Candida species covered from traditional cheeses: Characterization of C. albicans regarding virulence factors, biofilm formation, caseinase activity, antifungal resistance and phylogeny

This study has provided characterization data (carriage of virulence, antifungal resistance, caseinase activity, biofilm-forming ability and genotyping) of Candida albicans isolates and the occurrence of Candida species in traditional cheeses collected from Kayseri, Türkiye. Phenotypic (E-test, Congo red agar and microtiter plate tests) and molecular tests (identification, virulence factors, biofilm-formation, antifungal susceptibility) were carried out. The phylogenetic relatedness of C. albicans isolates was obtained by constructing the PCA dendrogram from the mass spectra data. Of 102 samples, 13 (12.7%) were found to be contaminated with C. albicans, 15 (14.7%), 10 (9.8%) and five (4.9%) were found to be contaminated with C. krusei, C. lusitane and C. paraplosis, respectively. While seven (16.2%) of 43 Candida spp. isolates were obtained from cheese collected from villages, 36 (83.7%) belonged to cheeses collected from traditional retail stores. The carriage rate of C. albicans isolates belonging to virulence factors HSP90 and PLB1 genes was 30.7%. ALST1, ALST3, BCR, ECE, andHWP (virulence and biofilm-associated) genes were harbored by 30.7%, 23%, 38.4%, 53.8%, and 38.4% of the 13 isolates. According to the microplate test, eight (61.5%) of 13 isolates had strong biofilm production. ERG11 and FKS1 (antifungal resistance genes) were found in 46.1% and 23% of 13 isolates, respectively. Due to missense mutations, K128T, E266D and V488I amino acid changes were detected for some isolates regarding azole resistance. As a result of the E-test, of the 13 isolates, one (7.6%) was resistant to flucytosine, four (30.7%) were resistant to caspofungin, and nine (69.2%) were resistant to fluconazole. The PCA analysis clustered the studied isolates into two major clades. C. albicans isolates of traditional cheese collected from villages were grouped in the same cluster. Among the C. albicans isolates from village cheese, there were those obtained from the same dairy milk at different times. Samples from the same sales points produced at different dairy farms were also contaminated with C. albicans. Concerning food safety standards applied from farm to fork, in order to prevent these pathogenic agents from contaminating cheeses, attention to the hygiene conditions of the sale points, conscious personnel, prevention of cross contamination will greatly reduce public health threats in addition to the application of animal health control, milking hygiene, pasteurization parameters in traditional cheese production.

An agricultural triazole induces genomic instability and haploid cell formation in the human fungal pathogen Candida tropicalis

The human fungal pathogen Candida tropicalis is widely distributed in clinical and natural environments. It is known to be an obligate diploid organism with an incomplete and atypical sexual cycle. Azole-resistant C. tropicalis isolates have been observed with increasing prevalence in many countries in recent years. Here, we report that tebuconazole (TBZ), a triazole fungicide widely used in agriculture, can induce ploidy plasticity and the formation of haploid cells in C. tropicalis. The evolved C. tropicalis strains with ploidy variations exhibit a cross-resistance between TBZ and standard azoles used in clinical settings (such as fluconazole and voriconazole). Similar to its diploid cells, these newly discovered C. tropicalis haploid cells are capable of undergoing filamentation, white-opaque switching, and mating. However, compared to its diploid cells, these haploid C. tropicalis cells grow more slowly under in vitro culture conditions and are less virulent in a mouse model of systemic infection. Interestingly, flow cytometry analysis of a clinical strain with extremely low genome heterozygosity indicates the existence of natural C. tropicalis haploids. Discovery of this C. tropicalis haploid state sheds new light into the biology and genetic plasticity of C. tropicalis and could provide the framework for the development of new genetic tools in the field.

A polyene macrolide targeting phospholipids in the fungal cell membrane

The global spread of multidrug-resistant pathogenic fungi presents a serious threat to human health, necessitating the discovery of antifungals with unique modes of action1. However, conventional activity-based screening for previously undescribed antibiotics has been hampered by the high-frequency rediscovery of known compounds and the lack of new antifungal targets2. Here we report the discovery of a polyene antifungal antibiotic, mandimycin, using a phylogeny-guided natural-product discovery platform. Mandimycin is biosynthesized by the mand gene cluster, has evolved in a distinct manner from known polyene macrolide antibiotics and is modified with three deoxy sugars. It has demonstrated potent and broad-spectrum fungicidal activity against a wide range of multidrug-resistant fungal pathogens in both in vitro and in vivo settings. In contrast to known polyene macrolide antibiotics that target ergosterol, mandimycin has a unique mode of action that involves targeting various phospholipids in fungal cell membranes, resulting in the release of essential ions from fungal cells. This unique ability to bind multiple targets gives it robust fungicidal activity as well as the capability to evade resistance. The identification of mandimycin using the phylogeny-guided natural-product discovery strategy represents an important advancement in uncovering antimicrobial compounds with distinct modes of action, which could be developed to combat multidrug-resistant fungal pathogens.

Identification and antifungal susceptibility patterns of reference yeast strains to novel and conventional agents: a comparative study using CLSI, EUCAST and Sensititre YeastOne methods

Objectives

The aim of this study was to identify and determine the MICs of 13 antifungal drugs, including the novel agents ibrexafungerp, manogepix and rezafungin, against 22 laboratory reference strains from 14 different Candida spp. and allied yeast genera using the EUCAST, CLSI and Sensititre™ YeastOne™ (SYO) methods.

Results

Complete agreement between molecular and proteomics methods was observed for identification. The compounds with the greatest in vitro activity, as indicated by the lowest geometric mean MIC (GM), were manogepix (GM: 0.01), isavuconazole (GM: 0.05) and rezafungin (GM: 0.03-0.07). The overall essential agreement (EA) (within ±0 to ±2 2-fold dilutions) between the reference methods, EUCAST and CLSI, was 95%, with results ranging from 82% (ibrexafungerp) to 100% (amphotericin B, anidulafungin, fluconazole, 5-flucytosine and micafungin). Regarding EA for EUCAST and CLSI compared with SYO, values were 91% and 89%, respectively. Nevertheless, when the MIC values were transformed into log2, significant differences were observed (e.g. fluconazole, ibrexafungerp and 5-flucytosine). At the species level, Candidozyma auris and Candida duobushaemulonii exhibited the highest number of cases with significant differences when comparing the three techniques for each antifungal.

Conclusions

The high EA observed reinforces the reliability of EUCAST, CLSI and SYO in guiding antifungal therapy. However, the differences in EA, particularly for ibrexafungerp and 5-flucytosine, highlight the importance of continued evaluation of these methodologies to ensure consistency. Given that antifungal susceptibility testing plays a critical role in treatment decisions, understanding these variations is essential to prevent potential misclassification of susceptibility profiles, which could impact clinical outcomes.

It's Here, It's There, There's Fungi Everywhere: A Case Series Utilizing Rezafungin for Invasive Candidiasis

Rezafungin is a long-acting echinocandin with broad coverage against Candida. Rezafungin has primarily been indicated for candidemia, with limited literature available on its use for infections outside of the bloodstream. Herein, three patient cases are presented from an academic medical center. Infectious processes presented include drug-resistant mucosal candidiasis, prosthetic joint infection, and candidemia involving Candida auris. In all three cases, patients received rezafungin. Clinical response was demonstrated in all patients as was tolerability of rezafungin. Together these cases provide further evidence for the use of rezafungin, including its use for treatment of invasive infections other than candidemia.

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.

Unveiling antifungal resistance and biocide tolerance in clinical isolates of Candida spp

AIMS

Candidiasis, caused by Candida spp. is an opportunistic infection with significant healthcare risks, worsened by trends in antifungal resistance. This study aimed to evaluate the antifungal susceptibility profile, investigate resistance mechanisms, assess efflux pump activity, and examine biocide tolerance in clinical Candida isolates.

METHODS

A total of 100 Candida isolates from hospitalized and outpatient individuals were analyzed for their antifungal susceptibility profile, molecular resistance mechanisms through PCR, efflux pump activity with the Cartwheel method, and biocide tolerance (sodium hypochlorite, hydrogen peroxide, and benzalkonium chloride), which was assessed by disk diffusion.

RESULTS

A high prevalence of resistance (87%) to at least one antifungal was observed, with 47.12% of isolates showing simultaneous multiple resistance to three azole derivatives. The highest antifungal agent resistance was observed for fluconazole (n = 70) and the highest susceptibility for amphotericin B (n = 1). The most common mutation was in the ERG11 gene (n = 38/43.7%). Efflux pump activity was detected in both C. albicans and non-albicans Candida species. Biocide testing revealed a higher tolerance for sodium hypochlorite, with an inhibition zone ranging from 18.25 (4.40) to 34.0 (4.00).

CONCLUSIONS

This study highlights significant antifungal resistance in Candida spp. particularly to azoles, stressing the need for improved infection control and novel therapeutic strategies.

Emerging Treatments in Neonatal Fungal Infections: Progress and Prospects

Fungal infections in neonates are potentially life threatening. The differential diagnosis for neonatal rashes is extensive, with common culprits including both bacteria and fungi. Candida albicans is the predominant fungal pathogen, causing infections that range from superficial disease to severe systemic conditions, including sepsis and meningitis. Neonates, especially those who are preterm, are particularly susceptible because of developmentally immature immune systems and the use of invasive procedures and devices in neonatal intensive care units. Congenital cutaneous candidiasis, acquired in utero or during delivery, can lead to disseminated infection with high mortality rates. Early diagnosis and prompt antifungal treatment are crucial but challenging because of subtle clinical presentations, making accurate identification of the offending organism essential for selecting the appropriate treatment. Candida species account for the majority of neonatal fungal infections, with different species necessitating distinct treatments because of varying susceptibility profiles. Aspergillus, another significant pathogen, poses high mortality risks and can present either cutaneously or systemically. Malassezia, though less common, primarily affects preterm infants with catheter-related fungemia. Other fungal species, including Zygomycetes, Trichosporon, and Cryptococcus, rarely produce neonatal infections but are noteworthy for consideration. Treatment of fungal infection is critical despite the relative paucity of information regarding the clinical pharmacology of many antifungal drugs in neonates. We review the major antifungal agents (e.g., amphotericin B, the echinocandins, the azoles) and provide pharmacologic and dosing information. Finally, preventive strategies, including the use of stringent aseptic techniques and careful clinical monitoring, are essential to mitigate both the incidence and severity of these infections in neonates and infants in the first months of life.

A hidden intrinsic ability of bicistronic expression based on a novel translation reinitiation mechanism in yeast

Gene organization in operons and co-expression as polycistronic transcripts is characteristic of prokaryotes. With the evolution of the eukaryotic translation machinery, operon structure and expression of polycistrons were largely abandoned. Whether eukaryotes still possess the ability to express polycistrons, and how they functionally activate bacterial operons acquired by horizontal DNA transfer is unknown. Here, we demonstrate that a polycistron can be rapidly activated in yeast by induction of bicistronic expression under selection. We show that induced translation of the downstream cistron in a bicistronic transcript is based on a novel type of reinitiation mediated by the 80S ribosome and triggered by inefficient stop codon recognition, and that induced bicistronic expression is stable and independent of cis-elements. These results provide key insights into the epigenetic mechanism of the pathway of activation. We also developed a yeast strain that efficiently expresses bicistronic constructs, but does not carry any genomic DNA sequence change, and utilized this strain to synthesize a high-value metabolite from a bicistronic expression construct. Together, our results reveal the capacity of yeast to express bicistrons in a previously unrecognized pathway. While this capacity is normally hidden, it can be rapidly induced by selection to improve fitness.

Indoloquinoline alkaloid neocryptolepine derivative inhibits Botrytis cinerea by targeting thiamine thiazole synthase

The emergence and rapid spread of multidrug-resistant Botrytis cinerea strains pose a great challenge to the quality and safety of agricultural products and the efficient use of pesticides. Previously unidentified fungicides and targets are urgently needed to combat B. cinerea-associated infections as alternative therapeutic options. In this study, the promising compound Z24 demonstrated efficacy against all tested plant pathogenic fungi. Thiamine thiazole synthase (Bcthi4) was identified as a target protein of Z24 by drug affinity responsive target stability (DARTS), cellular thermal shift assay (CETSA), and surface plasmon resonance (SPR) assays. Molecular docking and enzyme activity experiments have demonstrated that Z24 can affect the function of Bcthi4. Last, mechanistic studies show that Z24 inhibits thiamine biosynthesis by binding to Bcthi4 and induces up-regulation of alternative splicing [alternative 5' splice site (A5SS)] of the Bcthi4 gene. In conclusion, by targeting Bcthi4, Z24 has the potential to be developed as a previously unidentified anti-B. cinerea candidate.

Clinical aspects and recent advances in fungal diseases impacting human health

Fungal diseases are of growing clinical concern in human medicine as the result of changes in the epidemiology, diversity in clinical presentation, emergence of new pathogens, difficulties in diagnosis and increasing resistance to antifungals of current available classes. There is a need for high disease awareness among the public and healthcare physicians, improvement in diagnostic methods and the development of drugs from new therapeutic classes with an improved resistance profile. In this article, we will explore some key aspects of fungal diseases in humans and provide a general overview of this important topic.

Proton-Detected Solid-State NMR for Deciphering Structural Polymorphism and Dynamic Heterogeneity of Cellular Carbohydrates in Pathogenic Fungi

Carbohydrate polymers in their cellular context display highly polymorphic structures and dynamics essential to their diverse functions, yet they are challenging to analyze biochemically. Proton-detection solid-state NMR spectroscopy offers high isotopic abundance and sensitivity, enabling rapid and high-resolution structural characterization of biomolecules. Here, an array of 2D/3D 1H-detection solid-state NMR techniques are tailored to investigate polysaccharides in fully protonated or partially deuterated cells of three prevalent pathogenic fungi: Rhizopus delemar, Aspergillus fumigatus, and Candida albicans, representing filamentous species and yeast forms. Selective detection of acetylated carbohydrates reveals fifteen forms of N-acetylglucosamine units in R. delemar chitin, which coexists with chitosan as separate domains or polymers and associates with proteins only at limited sites. This is supported by distinct order parameters and effective correlation times of their motions, analyzed through relaxation measurements and model-free analysis. Five forms of α-1,3-glucan with distinct structural origins and dynamics were identified in A. fumigatus, important for this buffering polysaccharide to perform diverse roles of supporting wall mechanics and regenerating soft matrix under antifungal stress. Eight α-1,2-mannan sidechain variants in C. albicans were resolved, highlighting the crucial role of mannan sidechains in maintaining interactions with other cell wall polymers to preserve structural integrity. These methodologies provide novel insights into the functional structures of key fungal polysaccharides and create new opportunities for exploring carbohydrate biosynthesis and modifications across diverse organisms.

Cyclic N, O-acetals and corresponding opened N, N-aminals as new scaffolds with promising anti-inflammatory and antifungal activities against Candida albicans

P2 × 7R is crucial in the pathogenesis of chronic inflammatory diseases, and its activation leads to the release of pro-inflammatory cytokines, exacerbating the inflammatory response. Two new series of scarce cyclic N, O-acetals (ATF 61-74) and corresponding opened N, N-aminals (CS 1-14) have been designed as novel potential P2RX7 antagonists, then synthesized and evaluated for their anti-inflammatory properties through investigating the pro-inflammatory markers and also for their antifungal activity against Candida albicans. Three compounds (ATF 64, CS 8, and CS 9) exhibited dual antifungal and anti-inflammatory properties. ATF 64, CS 8, and CS 9 reduced ROS production and IL-1β expression in macrophages and intestinal cells in a manner correlated with NF-KB expression. These compounds showed excellent antifungal activity against clinical isolates of C. albicans resistant to fluconazole and caspofungin, and reduced C. albicans biofilm formation. Treatment with CS 8 or CS 9 protected the nematode Caenorhabditis elegans against infection with C. albicans and enhanced antimicrobial gene expression. This duality of action offers a promising new pharmacological strategy to counteract inflammatory diseases and propels N, N-aminals as promising candidates for future optimization and investigation.

Fungal microbiota in COPD patients during exacerbations

Acute exacerbations of chronic obstructive pulmonary disease (COPD) results in increased mortality and can be triggered by a range of factors, including microorganisms. Very little studies have examined the role of fungi and fungal diversity in COPD patients. The aim of the study was to determine the role of Candida in COPD during an exacerbation. Oral swabs, sputum, feces and whole blood samples were collected from the AECOPD patients and control group. Mycological and serological analysis were performed. Yeast were statistically significantly more often isolated from the AECOPD group (97.06%) than from the control group (26.32%). 7 species were isolated from the AECOPD, and 3 from the control group. Dominated Candida albicans followed by C. tropicalis. α-diversity was much greater in AECOPD patients than in controls. β-diversity was also assessed. A much higher level of antimycotic resistance was observed in isolates from the AECOPD group, which affects the effectiveness of therapy. Serological tests showed twice the frequency of positive results in the AECOPD group. The mycobiota of AECOPD patients is numerically and taxonomically richer than controls, including species less frequently recorded in humans. Our research confirms that fungal mycobiota may be a potential factor influencing the development of exacerbations and progression of COPD.

Antifungal Action of Valencene and Nootkatone Compounds in Association with Fluconazole and Their Mechanism of Action Against Candida spp. and Pichia kudriavzevii Strains

Candidemia is a public health challenge as it causes thousands of annual deaths and combating it has become difficult due to the development of resistance in Candida spp. Compounds derived from natural products may counter this resistance. Therefore, we evaluate the intrinsic and combined antifungal activity of valencene and nootkatone compounds and their possible mechanism of action against Candida spp. Using the microdilution method, the antifungal effect of sesquiterpenes and their combination with fluconazole was determined. The results comprised the yeast growth curve and its 50% Inhibitory Concentration (IC50). They showed that the compounds alone inhibited microbial growth at a concentration of 1024 µg/mL for valencene being able to kill the fungus Pichia kudriavzevii (Candida krusei), for nootkatone the inhibition occurred at 512 µg/mL and was able to kill the species P. kudriavzevii and Candida tropicalis. Combined with the antifungal, the inhibition occurred at low concentrations (2 and 4 µg/mL) against all strains except P. kudriavzevii, which the combination with nootkatone inhibited at 512 µg/mL. The IC50 revealed inhibition of the strains at higher concentrations in the compounds and fluconazole alone compared to the combination concentrations. In addition, both compounds acted through the production of reactive oxygen species, helping the antifungal against C. albicans and P. kudriavzevii, contributing minimally to compromising membrane viability. Thus, the compounds show promise for combined activity with fluconazole.

Structure-guided optimization of small molecules targeting Yck2 as a strategy to combat Candida albicans

Candida albicans is the most common cause of life-threatening fungal infection in the developed world but remains a therapeutic challenge. Protein kinases have been rewarding drug targets across diverse indications but remain untapped for antifungal development. Previously, screening kinase inhibitors against C. albicans revealed a 2,3-aryl-pyrazolopyridine, GW461484A (GW), which targets casein kinase 1 (CK1) family member Yck2. Here, we report optimization of GW via two complementary approaches, synthesis of bioisosteres possessing an imidazo[1,2-a]pyridine core, and R-group substitution of GW's pyrazolo[1,5-a]pyridine core. Characterization of compounds reveals two 6-cyano derivatives with improved pharmacological properties that retain whole-cell bioactivity and selectivity for fungal Yck2 compared to human CK1α. Efficacy studies in mice indicate both analogs possess single-agent activity against C. albicans resistant to first-line echinocandin antifungals and potentiate non-curative echinocandin treatment. Results validate Yck2 as an antifungal target and encourage further development of inhibitors acting by this previously unexploited mode of action.

Electrically-driven drug delivery into deep cutaneous tissue by conductive microneedles for fungal infection eradication and protective immunity

Fungal infections affect over 13 million people worldwide and are responsible for 1.5 million deaths annually. Some deep cutaneous fungal infections may extend the dermal barriers to cause systemic infection, resulting in substantial morbidity and mortality. However, the management of deep cutaneous fungal infection is challenging and yet overlooked by traditional treatments, which only offer limited drug availability within deep tissue. In this study, we have developed an electrically stimulated microneedle patch to deliver miconazole into the subcutaneous layer. We tested its antifungal efficacy using in vitro and ex vivo models that mimic fungal infection. Moreover, we confirmed its anti-fungal and wound-healing effects in a murine subcutaneous fungal infection model. Furthermore, our findings also showed that the combination of miconazole and applied current synergistically stimulated the nociceptive sensory nerves, thereby activating protective cutaneous immunity mediated by dermal dendritic and γδ-T cells. Collectively, this study provides a new strategy for minimally invasive delivery of therapeutic agents and the modulation of the neuro-immune axis in deep tissue.

Vidarabine as a novel antifungal agent against Candida albicans: insights on mechanism of action

Around 1.5 million mortality cases due to fungal infection are reported annually, posing a massive threat to global health. However, the effectiveness of current antifungal therapies in the treatment of invasive fungal infections is limited. Repurposing existing antifungal drugs is an advisable alternative approach for enhancing their effectiveness. This study evaluated the antifungal efficacy of the antiviral drug vidarabine against Candida albicans ATCC 90028. Antifungal susceptibility testing was performed by microbroth dilution assay and further processed to find the minimum fungicidal concentration. Investigation on probable mode of vidarabine action against C. albicans was assessed by using the ergosterol reduction assay, reactive oxygen species (ROS) accumulation, nuclear condensation, and apoptosis assay. Results revealed that C. albicans was susceptible to vidarabine action and exhibited minimum inhibitory concentration at 150 µg/ml. At a concentration of 300 µg/ml, vidarabine had fungicidal activity against C. albicans. 300 µg/ml vidarabine-treated C. albicans cells demonstrated 91% reduced ergosterol content. Annexin/FITC/PI assay showed that vidarabine (150 µg/ml) had increased late apoptotic cells up to 31%. As per the fractional inhibitory concentration index, vidarabine had synergistic activity with fluconazole and caspofungin against this fungus. The mechanism underlying fungicidal action of vidarabine was evaluated at the intracellular level, and probably because of increased nuclear condensation, enhanced ROS generation, and cell cycle arrest. In conclusion, this data is the first to report that vidarabine has potential to be used as a repurposed antifungal agent alone or in combination with standard antifungal drugs, and could be a quick and safe addition to existing therapies for treating fungal infections.