Candida auris: Epidemiology, biology, antifungal resistance, and virulence

Candida auris-associated hospitalizations and outbreaks, China, 2018-2023

The emerging human fungal pathogen Candida auris has become a serious threat to public health. This pathogen has spread to 10 provinces in China as of December 2023. Here we describe 312 C. auris-associated hospitalizations and 4 outbreaks in healthcare settings in China from 2018 to 2023. Three genetic clades of C. auris have been identified during this period. Molecular epidemiological analyses indicate that C. auris has been introduced and local transmission has occurred in multiple instances in China. Most C. auris isolated from China (98.7%) exhibited resistance to fluconazole, while only a small subset of strains were resistant to amphotericin B (4.2%) and caspofungin (2.2%).

Biological and genomic analyses of Clavispora sputum sp. nov., a novel potential fungal pathogen closely related to Clavispora lusitaniae (syn. Candida lusitaniae) and Candida auris

Several human fungal pathogens, including drug-resistant Candida auris and species of the Candida haemulonii complex, have emerged over the past two decades, posing new threats to human health. In this study, we report the isolation and identification of a novel species belonging to the genus Clavispora, herein named as Cl avispora sputum, from a clinical sputum sample of a COVID-19 patient. Cl . sputum is phylogenetically closely related to fungal pathogens Clavispora lusitaniae (syn. Candida lusitaniae) and C. auris. When grown on CHROMagar Candida Plus medium, Cl. sputum exhibited a similar coloration to C. auris strain CBS12372. Cl. sputum was able to develop weak filaments on CM medium. Although Cl. sputum and Cl. lusitaniae are phylogenetically closely related, comparative genomic and synteny analyses indicated significant chromosomal rearrangements between the two species. Although Cl. sputum could not grow at 37 °C under regular culture condition, an increased fungal burden in the lung tissue of a mouse systemic infection model implies that it could be a potential opportunistic pathogenic yeast in humans.

Investigating role of positively selected genes and mutation sites of ERG11 in drug resistance of Candida albicans

The steep increase in acquired drug resistance in Candida isolates has posed a great challenge in the clinical management of candidiasis globally. Information of genes and codon sites that are positively selected during evolution can provide insights into the mechanisms driving antifungal resistance in Candida. This study aimed to create a manually curated list of genes of Candida spp. reported to be associated with antifungal resistance in literature, and further investigate the structure-function implications of positively selected genes and mutation sites. Sequence analysis of antifungal drug resistance associated gene sequences from various species and strains of Candida revealed that ERG11 and MRR1 of C. albicans were positively selected during evolution. Four sites in ERG11 and two sites in MRR1 of C. albicans were positively selected and associated with drug resistance. These four sites (132, 405, 450, and 464) of ERG11 are predictive markers for azole resistance and have evolved over time. A well-characterized crystal structure of sterol-14-α-demethylase (CYP51) encoded by ERG11 is available in PDB. Therefore, the stability of CYP51 in complex with fluconazole was evaluated using MD simulations and molecular docking studies for two mutations (Y132F and Y132H) reported to be associated with azole resistance in literature. These mutations induced high flexibility in functional motifs of CYP51. It was also observed that residues such as I304, G308, and I379 of CYP51 play a critical role in fluconazole binding affinity. The insights gained from this study can further guide drug design strategies addressing antimicrobial resistance.

The identification of essential cellular genes is critical for validating drug targets

Accurately identifying biological targets is crucial for advancing treatment options. Essential genes, vital for cell or organism survival, hold promise as potential drug targets in disease treatment. Although many studies have sought to identify essential genes as therapeutic targets in medicine and bioinformatics, systematic reviews on their relationship with drug targets are relatively rare. This work presents a comprehensive analysis to aid in identifying essential genes as potential targets for drug discovery, encompassing their relevance, identification methods, successful case studies, and challenges. This work will facilitate the identification of essential genes as therapeutic targets, thereby boosting new drug development.

The Candida auris Hog1 MAP kinase is essential for the colonization of murine skin and intradermal persistence

Candida auris, a multidrug-resistant human fungal pathogen, was first identified in 2009 in Japan. Since then, systemic C. auris infections have now been reported in more than 50 countries, with mortality rates of 30%-60%. A major contributing factor to its high inter- and intrahospital clonal transmission is that C. auris, unlike most Candida species, displays unique skin tropism and can stay on human skin for a prolonged period. However, the molecular mechanisms responsible for C. auris skin colonization, intradermal persistence, and systemic virulence are poorly understood. Here, we report that C. auris Hog1 mitogen-activated protein kinase is essential for efficient skin colonization, intradermal persistence as well as systemic virulence. RNA-seq analysis of wild-type parental and hog1Δ mutant strains revealed marked downregulation of genes involved in processes such as cell adhesion, cell wall rearrangement, and pathogenesis in hog1Δ mutant compared to the wild-type parent. Consistent with these data, we found a prominent role for Hog1 in maintaining cell wall architecture, as the hog1Δ mutant demonstrated a significant increase in cell-surface β-glucan exposure and a concomitant reduction in chitin content. Additionally, we observed that Hog1 was required for biofilm formation in vitro and fungal survival when challenged with primary murine macrophages and neutrophils ex vivo. Collectively, these findings have important implications for understanding the C. auris skin adherence mechanisms and penetration of skin epithelial layers preceding bloodstream infections.

IMPORTANCE

Candida auris is a World Health Organization fungal priority pathogen and an urgent public health threat recognized by the Centers for Disease Control and Prevention. C. auris has a unique ability to colonize human skin. It also persists on abiotic surfaces in healthcare environments for an extended period of time. These attributes facilitate the inter- and intrahospital clonal transmission of C. auris. Therefore, understanding C. auris skin colonization mechanisms is critical for infection control, especially in hospitals and nursing homes. However, despite its profound clinical relevance, the molecular and genetic basis of C. auris skin colonization mechanisms are poorly understood. Herein, we present data on the identification of the Hog1 MAP kinase as a key regulator of C. auris skin colonization. These findings lay the foundation for further characterization of unique mechanisms that promote fungal persistence on human skin.

Early Introductions of Candida auris Detected by Wastewater Surveillance, Utah, USA, 2022-2023

Candida auris is considered a nosocomial pathogen of high concern and is currently spreading across the United States. Infection control measures for C. auris focus mainly on healthcare facilities, yet transmission levels may already be significant in the community before outbreaks are detected in healthcare settings. Wastewater-based epidemiology (culture, quantitative PCR, and whole-genome sequencing) can potentially gauge pathogen transmission in the general population and lead to early detection of C. auris before it is detected in clinical cases. To learn more about the sensitivity and limitations of wastewater-based surveillance, we used wastewater-based methods to detect C. auris in a southern Utah jurisdiction with no known clinical cases before and after the documented transfer of colonized patients from bordering Nevada. Our study illustrates the potential of wastewater-based surveillance for being sufficiently sensitive to detect C. auris transmission during the early stages of introduction into a community.

Genome-Guided Identification of Surfactin-Producing Bacillus halotolerans AQ11M9 with Anti-Candida auris Potential

The emergence of multidrug-resistant fungi Candida auris is a worldwide health crisis connected with high rates of mortality. There is a critical need to find novel and unique antifungal compounds for treating infections of multidrug-resistant fungi such as C. auris. This study aimed to illustrate that biosynthetic gene clusters in native bacterial isolates are able to produce antifungal compounds against the multidrug-resistant fungus C. auris. It was successfully achieved using large-scale antifungal activity screening, cytotoxicity analysis, and whole genome sequencing integrated with genome mining-guided analysis and liquid chromatography-mass spectrometry (LC/MS). A list of possible gene candidates was initially identified with genome mining methods to predict secondary metabolite gene clusters of antifungal-compound-producing bacteria. Then, gene clusters present in the antifungal-compound-producing bacteria were identified and aligned with the reference genome using comparative genomic approaches. Bacillus halotolerans AQ11M9 was identified through large-scale antifungal activity screening as a natural compound-producer against multidrug-resistant C. auris, while it was nontoxic to normal human skin fibroblast cells (confirmed using a cell viability assay). The genome (4,197,347 bp) of B. halotolerans AQ11M9 with 2931 predicted genes was first mined for detecting and characterizing biosynthetic gene clusters, which revealed 10 candidate regions with antifungal activity. Clusters of AQ11M9 encoded non-ribosomal peptide synthase (NRPS) (bacilysin, bacillibactin, paenibactin, surfactin, plipastin, and fengycin) and polyketide (macrobrevin). The presence of gene clusters with anti-C. auris activity, and surfactin identified through LC/MS, from AQ11M9 suggests the potential of utilizing it as a source for a novel and powerful anti-C. auris compound.

Lipids from a snail host regulate the multicellular behavior of a predator of parasitic schistosomes

Transmission of vector-borne diseases can be slowed by symbionts within the secondary hosts that spread disease. Snails spread schistosomiasis, and the snail symbiont Capsaspora owczarzaki kills schistosome larvae. In studying how Capsaspora colonizes its host snail, we discovered that Capsaspora responded to its host by forming multicellular aggregates. We elucidated the chemical cue for aggregation: hemolymph phosphatidylcholines (PCs). Furthermore, we uncovered that Capsaspora cells aggregate to different degrees in sera from different host snails-and these responses correlate with serum concentrations of PCs. Therefore, Capsaspora senses a host factor that can indicate the identity and physiological state of its host. Since cellular aggregation controls microbial motility, feeding, and immune evasion, this response within host tissue may be important for colonization. If so, snail serum PC and Capsaspora aggregation will be molecular and cellular markers to discern which conditions will favor the colonization of snails (and potential exclusion of schistosomes) by Capsaspora.

Baicalein induces apoptosis by targeting ribosomes in Candida auris

The emergence of the "super fungus" Candida auris poses a significant threat to human health, given its multidrug resistance and high mortality rates. Therefore, developing a new antifungal strategy is necessary. Our previous research showed that Baicalein (BE), a key bioactive compound from the dried root of the perennial herb Scutellaria baicalensis Georgi, has strong fungistatic properties against C. auris. Nevertheless, the antifungal activity of BE against C. auris and its mechanism of action requires further investigation. In this study, we explored how BE affects this fungus using various techniques, including scanning electron microscopy (SEM), Annexin V-FITC apoptosis detection, CaspACE FITC-VAD-FMK In Situ Marker, reactive oxygen species (ROS) assay, singlet oxygen sensor green (SOSG) fluorescent probe, enhanced mitochondrial membrane potential (MMP) assay with JC-1, DAPI staining, TUNEL assay and reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Our findings revealed that BE induced several apoptotic features, including phosphatidylserine (PS) externalization, metacaspase activation, nuclear condensation and DNA fragmentation. BE also increased intracellular ROS levels and altered mitochondrial functions. Additionally, transcriptomic analysis and RT-qPCR validation indicated that BE may induce apoptosis in C. auris by affecting ribosome-related pathways, suggesting that ribosomes could be new targets for antifungal agents, in addition to cell walls, membranes, and DNA. This study emphasizes the antifungal activity and mechanism of BE against C. auris, offering a promising treatment strategy for C. auris infection.

Resistance and virulence genes characteristic of a South Asia Clade (I) Candida auris strain isolated from blood in Beijing

INTRODUCTION

Candida auris is a globally disseminated invasive ascomycetous yeast, that imposes a substantial burden on healthcare systems. It has been documented to have spread to over 40 countries across six continents, necessitating in-depth comprehension through advanced techniques like Whole-Genome Sequencing.

METHOD

This study entailed the isolation and Whole-Genome Sequencing of a fluconazole-resistant C. auris strain (CA01) obtained from a patient's blood in Beijing. Genome analysis was conducted to classify the strain, and molecular docking was performed to understand the impact of mutations on drug resistance.

RESULTS

Genome analysis revealed that CA01 belongs to the South Asia Clade (I) and shares the closest genetic relationship with previously reported strains BJCA001 and BJCA002. Notably, unlike BJCA001, CA01 exhibits significant resistance to fluconazole primarily due to the A395T mutation in the ERG11 gene. Molecular docking studies demonstrated that this mutation leads to geometric changes in the active site where fluconazole binds, resulting in decreased binding affinity. Additionally, the present findings have identified several core virulence genes in C. auris, such as RBF1.

DISCUSSION

The findings from this study expand the understanding of the genetic diversity and adaptive mechanisms of C. auris within the South Asia Clade (I). The observed fluconazole resistance driven by the ERG11 mutation A395T highlights the need for heightened awareness and adaptation in clinical treatment strategies in China. This study provides critical insights into drug resistance and virulence profiles at a genetic level, which could guide future therapeutic and management strategies for C. auris infections.

Evaluation of amlodipine against strains of Candida spp. in planktonic cells, developing biofilms and mature biofilms

Aim: To evaluate the antifungal activity of amlodipine against strains of Candida spp. and to its possible mechanism of action.Methods: Broth microdilution tests were used to determine the minimum inhibitory concentration, while the synergistic activity was evaluated by calculating the fractional inhibitory concentration index. The action of amlodipine against biofilms was determined using the MTT assay and its possible mechanism of action was investigated through flow cytometry tests.Results: Amlodipine showed MICs ranging from 62.5 to 250 μg/ml, in addition to action against pre-formed and forming biofilms, with reductions between 50 and 90%. Amlodipine increases the externalization of phosphatidylserine and reduces the cell viability of fungal cells, suggesting apoptosis.Conclusion: Amlodipine had good antifungal activity against planktonic cells and biofilms of Candida spp., by leading the cells to apoptosis.

Review and Current Perspectives on DNA Topoisomerase I and II Enzymes of Fungi as Study Models for the Development of New Antifungal Drugs

Fungal infections represent a growing public health problem, mainly stemming from two phenomena. Firstly, certain diseases (e.g., AIDS and COVID-19) have emerged that weaken the immune system, leaving patients susceptible to opportunistic pathogens. Secondly, an increasing number of pathogenic fungi are developing multi-drug resistance. Consequently, there is a need for new antifungal drugs with novel therapeutic targets, such as type I and II DNA topoisomerase enzymes of fungal organisms. This contribution summarizes the available information in the literature on the biology, topology, structural characteristics, and genes of topoisomerase (Topo) I and II enzymes in humans, two other mammals, and 29 fungi (including Basidiomycetes and Ascomycetes). The evidence of these enzymes as alternative targets for antifungal therapy is presented, as is a broad spectrum of Topo I and II inhibitors. Research has revealed the genes responsible for encoding the Topo I and II enzymes of fungal organisms and the amino acid residues and nucleotide residues at the active sites of the enzymes that are involved in the binding mode of topoisomerase inhibitors. Such residues are highly conserved. According to molecular docking studies, antifungal Topo I and II inhibitors have good affinity for the active site of the respective enzymes. The evidence presented in the current review supports the proposal of the suitability of Topo I and II enzymes as molecular targets for new antifungal drugs, which may be used in the future in combined therapies for the treatment of infections caused by fungal organisms.

Ligand-based analysis of the antifungal potential of phytosterols and triterpenes isolated from Cryptostegia grandiflora against Candida auris FKBP12

Candida auris, a pathogenic fungus, has posed significant challenges to conventional medical treatments due to its increasing resistance to antifungal agents. Consequently, due to their promising pharmacological properties, there is a compelling interest in exploring novel bioactive compounds, such as phytosterols and triterpenes. This study aimed to conduct virtual screening utilizing computational methods, including ADMET, molecular docking, and molecular dynamics, to assess the activity and feasibility of phytosterols extracted from Cryptostegia grandiflora as potential therapeutic agents. Computational predictions suggest that compounds bearing structural similarities to Fsp3-rich molecules hold promise for inhibiting enzymes and G protein-coupled receptor (GPCR) modulators, with particular emphasis on ursolic acid, which, in its conjugated form, exhibits high oral bioavailability and metabolic stability, rendering it a compelling drug candidate. Molecular docking calculations identified ursolic acid and stigmasterol as promising ligands. While stigmasterol displayed superior affinity during molecular dynamics simulations, it exhibited instability, contrasting with ursolic acid's slightly lower affinity yet sustained stability throughout the dynamic assessments. This suggests that ursolic acid is a robust candidate for inhibiting the FKBP12 isomerase in C. auris. Moreover, further investigations could focus on experimentally validating the molecular docking predictions and evaluating the efficacy of ursolic acid as an FKBP12 isomerase inhibitor in models of C. auris infection.

Uniqueness of Candida auris cell wall in morphogenesis, virulence, resistance, and immune evasion

Candida auris has drawn global attention due to its alarming multidrug resistance and the emergence of pan resistant strains. C. auris poses a significant risk in nosocomial candidemia especially among immunocompromised patients. C. auris showed unique virulence characteristics associated with cell wall including cell polymorphism, adaptation, endurance on inanimate surfaces, tolerance to external conditions, and immune evasion. Notably, it possesses a distinctive cell wall composition, with an outer mannan layer shielding the inner 1,3-β glucan from immune recognition, thereby enabling immune evasion and drug resistance. This review aimed to comprehend the association between unique characteristics of C. auris's cell wall and virulence, resistance mechanisms, and immune evasion. This is particularly relevant since the fungal cell wall has no human homology, providing a potential therapeutic target. Understanding the complex interactions between the cell wall and the host immune system is essential for devising effective treatment strategies, such as the use of repurposed medications, novel therapeutic agents, and immunotherapy like monoclonal antibodies. This therapeutic targeting strategy of C. auris holds promise for effective eradication of this resilient pathogen.

Prevalence and Outcomes of Candida auris Infections in a Tertiary Hospital in the United Arab Emirates (UAE)

Background Candida auris (C. auris) is an emerging serious threat to healthcare settings, with an average mortality of 45% in cases of bloodstream infections. This study aimed to determine the prevalence of C. auris in a single center in the UAE during the year 2022 and understand risk factors related to poor outcomes. Methods This retrospective cohort chart review at Al-Qassimi Hospital encompassed all confirmed Candida infections, including C. auris, from January to December 2022. The study involved male and female patients aged 13 years and older, using comprehensive data extracted from the hospital's electronic healthcare records. The analysis included clinical, laboratory, and epidemiological data. Adhering to the 2011 Declaration of Helsinki and Good Pharmacoepidemiology Practices, the study received Institutional Review Board approval, with informed consent waived due to its retrospective design. Data were summarized using appropriate statistical methods, including the unpaired t-test, Mann-Whitney U test, Chi-square test, and Fisher exact test. A significance level of 95% (p<0.05) was maintained throughout the statistical analyses. Results Of the 75 confirmed Candidainfections, 53 (70.7%) were C. auris-positive cases. About 23 (43.4%) of the C. auris group were above 65 years old. Most cases of C. auris group were hospital-acquired (49, 92.5%). The highest number of positive cases were found in urine samples. The demographic and clinical profiles of the C. auris and non-auris groups candidemia were largely similar, except for differences in antifungal use history and ICU requirements. Notably, the C. auris group had a significantly lower history of antifungal use and a lower ICU requirement compared to the non-auris group. The study also highlighted the higher mortality rate associated with candidemia. While mortality was higher in the non-auris group, the difference was not statistically significant. Conclusions The findings of the study suggest that while C. auris poses a serious threat, particularly in hospital settings; the clinical and demographic factors influencing its spread and impact are complex and warrant further investigation. Understanding these factors is crucial for developing effective strategies to prevent and manage C. auris infections, particularly in vulnerable patient populations.

Insight into Virulence and Mechanisms of Amphotericin B Resistance in the Candida haemulonii Complex

The Candida haemulonii complex includes emerging opportunistic human fungal pathogens with documented multidrug-resistance profiles. It comprises Candida haemulonii sensu stricto, Candida haemulonii var. vulnera, Candida duobushaemulonii, Candida pseudohaemulonii, and Candida vulturna. In recent years, rates of clinical isolation of strains from this complex have increased in multiple countries, including China, Malaysia, and Brazil. Biofilm formation, hydrolytic enzymes, surface interaction properties, phenotype switching and cell aggregation abilities, extracellular vesicles production, stress response, and immune evasion help these fungi to infect the host and exert pathological effects. Multidrug resistance profiles also enhance the threat they pose; they exhibit low susceptibility to echinocandins and azoles and an intrinsic resistance to amphotericin B (AMB), the first fungal-specific antibiotic. AMB is commonly employed in antifungal treatments, and it acts via several known mechanisms. Given the propensity of clinical Candida species to initiate bloodstream infections, clarifying how C. haemulonii resists AMB is of critical clinical importance. This review outlines our present understanding of the C. haemulonii complex's virulence factors, the mechanisms of action of AMB, and the mechanisms underlying AMB resistance.

Two outbreaks and sporadic occurrences of Candida auris from one hospital in China: an epidemiological, genomic retrospective study

OBJECTIVES

To investigate the clinical relevance, origin, transmission, and resistance of Candida auris (C. auris) isolates from two outbreaks and sporadic occurrences from one hospital in China.

METHODS

A total of 135 C. auris isolates were collected. Clinical characteristics were obtained and antifungal susceptibility testing (AFST) was performed using the method of broth microdilution. Phylogenetic tree, WGS analysis, and single nucleotide polymorphisms (SNPs) were used to determine the origin, transmission, and resistance mechanisms.

RESULTS

A total of 31 patients (91.2%, 31/34) received invasive medical procedures and 13 patients (38.2%, 13/34) had antifungal agents before C. auris infection/colonization, except one patient whose clinical information was missing. Only 4 cases of C. auris candidemia were observed. 18 patients died, 13 patients recovered, and the outcomes of 3 patients were not available. A total of 35 C. auris isolates, which were successfully cultivated and the first isolated or harbored specific drug-resistant phenotype from each patient, were selected to be sequenced and further analyzed. C. auris isolates presented low genetic variability and belonged to clade I, possibly originating from BJ004-H7 in Beijing. All 35 isolates were resistant to Fluconazole (FCZ) and amphotericin B (AMB), and 3 isolates were resistant to caspofungin (CAS). Mutations in ERG11 and FKS1 were linked to reduced azole and echinocandin susceptibility, respectively.

CONCLUSIONS

Two outbreaks of highly clonal, multidrug-resistant C. auris isolates within the medical facility were reported. The intensive performance of disinfection measures helped block in-hospital transmission. Understanding the epidemiology, drug resistance and management of C. auris will be helpful for implementing effective infection control and treatment strategies.

Sensitivity Analysis of C. auris, S. cerevisiae, and C. cladosporioides by Irradiation with Far-UVC, UVC, and UVB

Background

The World Health Organization has published a list of pathogenic fungi with prior-itizing groups and calls for research and development of antifungal measures, with Candida auris belonging to the group with high priority.

Methods

The photosensitivity towards short wavelength ultraviolet irradiation (Far-UVC, UVC, and UVB) was investigated and compared to other yeasts (Saccharomyces cerevisiae) and a mold (Cladosporium cladosporioides). The observed 1-log reduction doses were compared to literature values of other representatives of the genus Candida, but also with S. cerevisiae, Aspergillus niger, and A. fumigatus.

Results

For the determined 1-log reduction doses, an increase with higher wavelengths was observed. A 1-log reduction dose of 4.3 mJ/cm2 was determined for C. auris when irradiated at 222 nm, a dose of 6.1 mJ/cm2 at 254 nm and a 1-log reduction dose of 51.3 mJ/cm2 was required when irradiated with UVB.

Conclusions

It was observed that S. cerevisiae is a possible surrogate for C. auris for irradiation with Far-UVC and UVB due to close 1-log reduction doses. No surrogate suitability was verified for C. cladosporioides in relation to A. niger and A. fumigatus for irradiation with a wavelength of 254 nm and for A. niger at 222 nm.

Antifungal Activity of the Dichloromethane Extract of CaoHuangGuiXiang Formula Against Candida auris by in vitro and in vivo Evaluation

Purpose

CaoHuangGuiXiang (CHGX) formula is a traditional Chinese medicine for the treatment of Candida-related infection. However, its antifungal mechanisms against the emerging fungal pathogen Candida auris remain unclear. This study aimed to evaluate the antifungal activity of the dichloromethane extract of CHGX (CHGX-DME) and clarified its antifungal mechanims against C. auris.

Methods

The major components of CHGX-DME were identified by ultra-performance liquid chromatography tandem mass spectrometry. Then, the minimal inhibitory concentration (MIC) assay and the time-kill kinetic assay were performed to investigate the in vitro antifungal activity of CHGX-DME against C. auris, including 8 isolates of 4 discrete clades and 2 special phenotypes (filamentous and aggregative). Furthermore, the effect of CHGX-DME on biofilm development was examined. In addition, the in vivo toxicity and efficacy of CHGX-DME were evaluated in a Galleria mellonella infection model.

Results

First, 20 major compounds in CHGX-DME were detected and characterized. The MIC50% and MIC90% of CHGX-DME against C. auris isolates ranged from 50-200 mg/L and 100-400 mg/L, respectively. At 400 mg/L, CHGX-DME was able to efficiently kill more than 70% and 90% of C. auris cells after 3 hours and 6 hours of treatment, respectively. This notable antifungal activity exhibited a dosage- and time-dependent manner. Moreover, CHGX-DME not only played a critical role in inhibiting the proliferation of filamentous and aggregative cells, but also showed restricting effect on biofilm development in C. auris. Importantly, it significantly improved the survival rate and reduced the fungal burden in G. mellonella infection models, suggesting a remarkable treatment effect against C. auris infection.

Conclusion

CHGX-DME exhibited potent antifungal activity against C. auris and significantly ameliorated this fungal infection in the G. mellonella model, confirming that it would be a promising antifungal drug for the troublesome and emerging fungal pathogen C. auris.

Barbosa E, Rocha HAO, Chaves GM. Mechanism of action and synergistic effect of Eugenia uniflora extract in Candida spp

The limited arsenal of antifungal drugs have prompted the search for novel molecules with biological activity. This study aimed to characterize the antifungal mechanism of action of Eugenia uniflora extract and its synergistic activity with commercially available antifungal drugs on the following Candida species: C. albicans, C. tropicalis, C. glabrata, C. parapsilosis and C. dubliniensis. In silico analysis was performed to predict antifungal activity of the major compounds present in the extract. Minimal inhibitory concentrations (MICs) were determined in the presence of exogenous ergosterol and sorbitol. Yeast cells were grown in the presence of stressors. The loss of membrane integrity was assessed using propidium iodide staining (fluorescence emission). Synergism between the extract and antifungal compounds (in addition to time kill-curves) was determined. Molecular docking revealed possible interactions between myricitrin and acid gallic and enzymes involved in ergosterol and cell wall biosynthesis. Candida cells grown in the presence of the extract with addition of exogenous ergosterol and sorbitol showed 2 to 8-fold increased MICs. Strains treated with the extract revealed greater loss of membrane integrity when compared to their Fluconazole counterparts, but this effect was less pronounced than the membrane damage caused by Amphotericin B. The extract also made the strains more susceptible to Congo red and Calcofluor white. A synergistic action of the extract with Fluconazole and Micafungin was observed. The E. uniflora extract may be a viable option for the treatment of Candida infections.

Candida spp.: the burden of a microorganism in a microbiology department

There is no precise information available on the entire workload of isolating a specific microorganism in a clinical microbiology laboratory, and the costs associated with it have not been specifically estimated. In this descriptive retrospective study conducted at the microbiology department of a general teaching hospital from January 2021 to December 2022, we assessed the workload associated with identifying Candida species in all types of clinical samples and patients. Costs were estimated from data obtained from the hospital's finance department and microbiology laboratory cost records. In 2 years, 1,008,231 samples were processed at our microbiology department, of which 8,775 had one or more Candida spp. isolates (9,683 total isolates). Overall, 5,151 samples with Candida spp. were identified from 2,383 inpatients. We isolated Candida spp. from 515.3 samples/100,000 population/year and from 92 samples/1,000 hospital admissions/year. By sample type, 90.8% were superficial, mainly mucosal. Only 9.1% Candida spp. were isolated from deep, usually sterile, samples, being mostly from ordinarily sterile fluids. Candida albicans was the main species (58.5%) identified, followed by C. parapsilosis complex, C. glabrata, C. tropicalis, and C. krusei. In admitted patients, the incidences of samples with Candida spp. isolates were 302.7 samples/100,000 population/year and 54 samples/1,000 admissions/year. The average cost of isolating and identifying Candida spp. was estimated at 25€ per culture-positive sample. To our knowledge, this is the first attempt to gage the workload and costs of Candida spp. isolation at a hospital microbiology department. These data can help assess the burden and significance of Candida isolation at other institutions and also help design measures for streamlining.

IMPORTANCE

We believe that this work is of interest because at present, there is no really accurate information available on the total workload involved in isolating a specific microorganism in a clinical microbiology laboratory. The costs related to this have also not been described. We have described the unrestricted workload of Candida spp. in all types of samples for all types of species and patients. We believe that this information would be necessary to collect and share this information as well as to collect it in a standardized way to know the current situation of Candida spp. workload in all clinical microbiology laboratories.

Candida auris inpatient screening in collaboration with the public health department

Candida auris is a multidrug-resistant fungal pathogen that is associated with nosocomial outbreaks in patients with extensive health care exposure and treatment outside the United States. The Ohio Department of Health recommends C auris screening in high-risk patients. However, this can be operationally difficult for many health care facilities. This report describes a C auris and carbapenem-resistant Enterobacterales inpatient screening program done in collaboration with state public health.

Yeast and filamentous Candida auris stimulate distinct immune responses in the skin

Candida auris, an emerging multidrug-resistant fungal pathogen, predominately colonizes the human skin long term leading to subsequent life-threatening invasive infections. Fungal morphology is believed to play a critical role in modulating mucocutaneous antifungal immunity. In this study, we used an intradermal mouse model of C. auris infection to examine fungal colonization and the associated innate and adaptive immune response to yeast and filamentous C. auris strains. Our results indicate that mice infected with a filamentous C. auris had significantly decreased fungal load compared to mice infected with the yeast form. Mice infected with yeast and filamentous forms of C. auris stimulated distinct innate immune responses. Phagocytic cells (CD11b+Ly6G+ neutrophils, CD11b+Ly6Chi inflammatory monocytes, and CD11b+MHCII+CD64+ macrophages) were differentially recruited to mouse skin tissue infected with yeast and filamentous C. auris. The percentage and absolute number of interleukin 17 (IL-17) producing innate lymphoid cells, TCRγδ+, and CD4+ T cells in the skin tissue of mice infected with filamentous C. auris were significantly increased compared to the wild-type of yeast strain. Furthermore, complementation of filamentous mutant strain of C. auris (Δelm1 + ELM1) strain exhibited wild-type yeast morphology in vivo and induced comparable level of skin immune responses similar to mice infected with yeast strain. Collectively, our findings indicate that yeast and filamentous C. auris induce distinct local immune responses in the skin. The decreased fungal load observed in mouse skin infected with filamentous C. auris is associated with a potent IL-17 immune response induced by this morphotype.IMPORTANCECandida auris is a globally emerging fungal pathogen that transmits among individuals in hospitals and nursing home residents. Unlike other Candida species, C. auris predominantly colonizes and persists in skin tissue resulting in outbreaks of systemic infections. Understanding the factors that regulate C. auris skin colonization and host immune response is critical to develop novel preventive and therapeutic approaches against this emerging pathogen. We identified that yeast and filamentous forms of C. auris induce distinct skin immune responses in the skin. These findings may help explain the differential colonization and persistence of C. auris morphotypes in skin tissue. Understanding the skin immune responses induced by yeast and filamentous C. auris is important to develop novel vaccine strategies to combat this emerging fungal pathogen.

Comprehensive Overview of Candida auris: An Emerging Multidrug-Resistant Fungal Pathogen

The rise of Candida auris, a multidrug-resistant fungal pathogen, across more than 40 countries, has signaled an alarming threat to global health due to its significant resistance to existing antifungal therapies. Characterized by its rapid spread and robust drug resistance, C. auris presents a critical challenge in managing infections, particularly in healthcare settings. With research on its biological traits and genetic basis of virulence and resistance still in the early stages, there is a pressing need for a concerted effort to understand and counteract this pathogen. This review synthesizes current knowledge on the epidemiology, biology, genetic manipulation, pathogenicity, diagnostics, and resistance mechanisms of C. auris, and discusses future directions in research and therapeutic development. By exploring the complexities surrounding C. auris, we aim to underscore the importance of advancing research to devise effective control and treatment strategies.

A multicentric outbreak of Candida auris in Mexico: 2020 to 2023

BACKGROUND

Candida auris, an emerging multidrug-resistant yeast, has become a global concern due to its association with nosocomial outbreaks and resistance to antifungal medications. The COVID-19 pandemic has exacerbated the situation, with several outbreaks reported worldwide, including in Mexico. We describe the clinical and microbiological characteristics of a multicentric outbreak in private institutions in Mexico.

METHODS

A retrospective observational study was conducted across 4 Christus Muguerza Hospital Health Care System facilities in Monterrey, Mexico, where simultaneous outbreaks of C auris occurred. Patients with colonization or infection with C auris between September 2020 and December 2023 were included.

RESULTS

Analysis revealed 37 cases, predominantly male (median age, 55.8years). While most cases were initially colonization, a significant proportion progressed to infection (32.4%). Patients with documented infection had longer intensive care unit and hospital stays, often requiring mechanical ventilation. Antifungal treatment varied, with empirical fluconazole being the first drug in most cases, followed by anidulafungin and caspofungin. Resistance to fluconazole was widespread, but susceptibility to other antifungals varied. The overall mortality rates were high (40.5%), with no significant difference in median survival between colonized and infected patients.

CONCLUSIONS

We reported a high rate of infection in previously colonized cases associated with longer hospital lenght stay, and a high susceptibility to echinocandins.

Suppressing the virulence factors of Candida auris with baicalein through multifaceted mechanisms

Candida auris, a rapidly spreading multi-drug-resistant fungus, is causing lethal infections under certain conditions globally. Baicalin (BE), an active ingredient extracted from the dried root of Scutellaria baicalensis Georgi, exhibits antifungal activity. However, studies have shown the distinctive advantages of Traditional Chinese medicine in combating fungal infections, while the effect of BE, an active ingredient extracted from the dried roots of Scutellaria baicalensis Georgi, on C. auris, remains unknown. Therefore, this study aims to evaluate the potential of BE as an antifungal agent against the emerging multidrug-resistant C. auris. Various assays and models, including microbroth dilution, time growth curve analysis, spot assays, adhesion tests, flocculation test, cell surface hydrophobicity assay, hydrolase activity assays, XTT assay, violet crystal assay, scanning electron microscope (SEM), confocal laser scanning microscope (CLSM), flow cytometry, Live/dead fluorescent staining, reactive oxygen species (ROS), cell wall assay, aggregation assay, porcine skin model, Galleria mellonella larvae (G. mellonella larvae) infection model, and reverse transcription-quantitative polymerase chain reaction (RT-PCR) were utilized to investigate how baicalein suppresses C. auris through possible multifaceted mechanisms. The findings indicate that BE strongly inhibited C. auris growth, adhesion, and biofilm formation. It also effectively reduced drug resistance and aggregation by disrupting the cell membrane and cell wall while reducing colonization and invasion of the host. Transcriptome analysis showed significant modulation in gene expression related to different virulence factors post-BE treatment. In conclusion, BE exhibits significant effectiveness against C. auris, suggesting its potential as a viable treatment option due to its multifaceted suppression mechanisms.

Candida auris from the Egyptian cobra: Role of snakes as potential reservoirs

Candida auris represents one of the most urgent threats to public health, although its ecology remains largely unknown. Because amphibians and reptiles may present favorable conditions for C. auris colonization, cloacal and blood samples (n = 68), from several snake species, were cultured and molecularly screened for C. auris using molecular amplification of glycosylphosphatidylinositol protein-encoding genes and ribosomal internal transcribed spacer sequencing. Candida auris was isolated from the cloacal swab of one Egyptian cobra (Naja haje legionis) and molecularly identified in its cloaca and blood. The isolation of C. auris from wild animals is herein reported for the first time, thus suggesting the role that these animals could play as reservoirs of this emerging pathogen. The occurrence of C. auris in blood requires further investigation, although the presence of cationic antimicrobial peptides in the plasma of reptiles could play a role in reducing the vitality of the fungus.

A single gene mutation underpins metabolic adaptation and acquisition of filamentous competence in the emerging fungal pathogen Candida auris

Filamentous cell growth is a vital property of fungal pathogens. The mechanisms of filamentation in the emerging multidrug-resistant fungal pathogen Candida auris are poorly understood. Here, we show that exposure of C. auris to glycerol triggers a rod-like filamentation-competent (RL-FC) phenotype, which forms elongated filamentous cells after a prolonged culture period. Whole-genome sequencing analysis reveals that all RL-FC isolates harbor a mutation in the C2H2 zinc finger transcription factor-encoding gene GFC1 (Gfc1 variants). Deletion of GFC1 leads to an RL-FC phenotype similar to that observed in Gfc1 variants. We further demonstrate that GFC1 mutation causes enhanced fatty acid β-oxidation metabolism and thereby promotes RL-FC/filamentous growth. This regulation is achieved through a Multiple Carbon source Utilizer (Mcu1)-dependent mechanism. Interestingly, both the evolved RL-FC isolates and the gfc1Δ mutant exhibit an enhanced ability to colonize the skin. Our results reveal that glycerol-mediated GFC1 mutations are beneficial during C. auris skin colonization and infection.

Mechanism of azole resistance in Candida vulturna, an emerging multidrug resistant pathogen related with Candida haeumulonii and Candida auris

BACKGROUND

Candida vulturna is an emerging pathogen belonging to the Metshnikowiaceae family together with Candida auris and Candida haemulonii species complex. Some strains of this species were reported to be resistant to several antifungal agents.

OBJECTIVES

This study aims to address identification difficulties, evaluate antiungal susceptibilities and explore the molecular mechanisms of azole resistance of Candida vulturna.

METHODS

We studied five C. vulturna clinical strains isolated in three Colombian cities. Identification was performed by phenotypical, proteomic and molecular methods. Antifungal susceptibility testing was performed following CLSI protocol. Its ERG11 genes were sequenced and a substitution was encountered in azole resistant isolates. To confirm the role of this substitution in the resistance phenotype, Saccharomyces cerevisiae strains with a chimeric ERG11 gene were created.

RESULTS

Discrepancies in identification methods are highlighted. Sequencing confirmed the identification as C. vulturna. Antifungal susceptibility varied among strains, with four strains exhibiting reduced susceptibility to azoles and amphotericin B. ERG11 sequencing showed a point mutation (producing a P135S substitution) that was associated with the azole-resistant phenotype.

CONCLUSIONS

This study contributes to the understanding of C. vulturna's identification challenges, its susceptibility patterns, and sheds light on its molecular mechanisms of azole resistance.

Clinical and microbiological characteristics of a hospital outbreak of Candida auris in a referral hospital in Lima, Peru

BACKGROUND

Candida auris, a multidrug-resistant fungal pathogen, has received considerable attention owing to its recent surge, especially in South America, which coincides with the ongoing global COVID-19 pandemic. Understanding the clinical and microbiological characteristics of outbreaks is crucial for their effective management and control.

OBJECTIVE

This retrospective observational study aimed to characterize a C. auris outbreak at a Peruvian referral hospital between January 2021 and July 2023.

METHODS

Data were collected from hospitalized patients with positive C. auris culture results. Microbiological data and antifungal susceptibility test results were analysed. Additionally, infection prevention and control measures have been described. Statistical analysis was used to compare the characteristics between the infected and colonized patients.

RESULTS

Thirty-three patients were identified, mostly male (66.7%), with a median age of 53 years. Among them, 18 (54.5%) were colonized, and 15 (45.5%) were infected. Fungemia was the predominant presentation (80%), with notable cases of fungemia in tuberculosis patients with long-stay devices for parenteral anti-tuberculosis therapy. Seventy-five percent of the isolates exhibited fluconazole resistance. Echinocandins were the primary treatment, preventing fungemia recurrence within 30 days. Infected patients had significantly longer hospital stays than colonized patients (100 vs. 45 days; p = .023). Hospital mortality rates were 46.7% and 25% in the infected and fungemia patients, respectively. Simultaneous outbreaks of multidrug-resistant bacteria were documented.

CONCLUSIONS

This study underscores the severity of a C. auris outbreak at a referral hospital in Peru, highlighting its significant impact on patient outcomes and healthcare resources. The high prevalence of fluconazole-resistant isolates, leading to prolonged hospital stay and high mortality rates, particularly in cases of fungemia, underscores the critical need for effective infection prevention and control strategies.

Saps1-3 Antigens in Candida albicans: Differential Modulation Following Exposure to Soluble Proteins, Mammalian Cells, and Infection in Mice

The secreted aspartic peptidases (Saps) of Candida albicans play crucial roles in various steps of fungal-host interactions. Using a flow cytometry approach, this study investigated the expression of Saps1-3 antigens after (i) incubation with soluble proteins, (ii) interaction with mammalian cells, and (iii) infection in immunosuppressed BALB/c mice. Supplementation strategies involving increasing concentrations of bovine serum albumin (BSA) added to yeast carbon base (YCB) medium as the sole nitrogenous source revealed a positive and significant correlation between BSA concentration and both the growth rate and the percentage of fluorescent cells (%FC) labeled with anti-Saps1-3 antibodies. Supplementing the YCB medium with various soluble proteins significantly modulated the expression of Saps1-3 antigens in C. albicans. Specifically, immunoglobulin G, gelatin, and total bovine/human sera significantly reduced the %FC, while laminin, human serum albumin, fibrinogen, hemoglobin, and mucin considerably increased the %FC compared to BSA. Furthermore, co-cultivating C. albicans yeasts with either live epithelial or macrophage cells induced the expression of Saps1-3 antigens in 78% (mean fluorescence intensity [MFI] = 152.1) and 82.7% (MFI = 178.2) of the yeast cells, respectively, compared to BSA, which resulted in 29.3% fluorescent cells (MFI = 50.9). Lastly, the yeasts recovered from the kidneys of infected immunosuppressed mice demonstrated a 4.8-fold increase in the production of Saps1-3 antigens (MFI = 246.6) compared to BSA, with 95.5% of yeasts labeled with anti-Saps1-3 antibodies. Altogether, these results demonstrated the positive modulation of Saps' expression in C. albicans by various key host proteinaceous components, as well as by in vitro and in vivo host challenges.

Fourier Transform Infrared Spectroscopy Application for Candida auris Outbreak Typing in a Referral Intensive Care Unit: Phylogenetic Analysis and Clustering Cut-Off Definition

Recently Candida auris has emerged as a multi-resistant fungal pathogen, with a significant clinical impact, and is able to persist for a long time on human skin and hospital environments. It is a critical issue on the WHO fungal priority list and therefore it is fundamental to reinforce hospital surveillance protocols to limit nosocomial outbreaks. The purpose of this study was to apply Fourier transform infrared spectroscopy (FT-IR) to investigate the phylogenetic relationships among isolated strains from a C. auris outbreak at the University Intensive Care Unit of a Tertiary University hospital in Turin (Italy). To calculate a clustering cut-off, intra- and inter-isolate, distance values were analysed. The data showed the presence of a major Alfa cluster and a minor Beta cluster with a defined C. auris clustering cut-off. The results were validated by an external C. auris strain and Principal Component and Linear Discriminant Analyses. The application of FT-IR technology allowed to obtain important information about the phylogenetic relationships between the analysed strains, defining for the first time a "not WGS-based" clustering cut-off with a statistical-mathematical approach. FT-IR could represent a valid alternative to molecular methods for the rapid and cost-saving typing of C. auris strains with important clinical implications.

Candida auris-a systematic review to inform the world health organization fungal priority pathogens list

The World Health Organization (WHO) in 2022 developed a fungal priority pathogen list. Candida auris was ultimately ranked as a critical priority pathogen. PubMed and Web of Science were used to find studies published from 1 January 2011 to 18 February 2021, reporting on predefined criteria including: mortality, morbidity (i.e., hospitalization and disability), drug resistance, preventability, yearly incidence, and distribution/emergence. Thirty-seven studies were included in the final analysis. The overall and 30-day mortality rates associated with C. auris candidaemia ranged from 29% to 62% and 23% to 67%, respectively. The median length of hospital stay was 46-68 days, ranging up to 140 days. Late-onset complications of C. auris candidaemia included metastatic septic complications. Resistance rates to fluconazole were as high as 87%-100%. Susceptibility to isavuconazole, itraconazole, and posaconazole varied with MIC90 values of 0.06-1.0 mg/l. Resistance rates to voriconazole ranged widely from 28% to 98%. Resistance rates ranged between 8% and 35% for amphotericin B and 0%-8% for echinocandins. Over the last ten years, outbreaks due to C. auris have been reported in in all WHO regions. Given the outbreak potential of C. auris, the emergence and spread of MDR strains, and the challenges associated with its identification, and eradication of its environmental sources in healthcare settings, prevention and control measures based on the identified risk factors should be evaluated for their effectiveness and feasibility. Global surveillance studies could better inform the incidence rates and distribution patterns to evaluate the global burden of C. auris infections.

Antifungal resistance: why are we losing this battle?

The emergence of fungal pathogens and changes in the epidemiological landscape are prevalent issues in clinical mycology. Reports of resistance to antifungals have been reported. This review aims to evaluate molecular and nonmolecular mechanisms related to antifungal resistance. Mutations in the ERG genes and overexpression of the efflux pump (MDR1, CDR1 and CDR2 genes) were the most reported molecular mechanisms of resistance in clinical isolates, mainly related to Azoles. For echinocandins, a molecular mechanism described was mutation in the FSK genes. Furthermore, nonmolecular virulence factors contributed to therapeutic failure, such as biofilm formation and selective pressure due to previous exposure to antifungals. Thus, there are many public health challenges in treating fungal infections.

The Potential of Dutasteride for Treating Multidrug-Resistant Candida auris Infection

Novel antifungal drugs are urgently needed to treat candidiasis caused by the emerging fungal multidrug-resistant pathogen Candida auris. In this study, the most cost-effective drug repurposing technology was adopted to identify an appropriate option among the 1615 clinically approved drugs with anti-C. auris activity. High-throughput virtual screening of 1,3-beta-glucanosyltransferase inhibitors was conducted, followed by an analysis of the stability of 1,3-beta-glucanosyltransferase drug complexes and 1,3-beta-glucanosyltransferase-dutasteride metabolite interactions and the confirmation of their activity in biofilm formation and planktonic growth. The analysis identified dutasteride, a drug with no prior antifungal indications, as a potential medication for anti-auris activity in seven clinical C. auris isolates from Saudi Arabian patients. Dutasteride was effective at inhibiting biofilm formation by C. auris while also causing a significant reduction in planktonic growth. Dutasteride treatment resulted in disruption of the cell membrane, the lysis of cells, and crushed surfaces on C. auris, and significant (p-value = 0.0057) shrinkage in the length of C. auris was noted at 100,000×. In conclusion, the use of repurposed dutasteride with anti-C. auris potential can enable rapid recovery in patients with difficult-to-treat candidiasis caused by C. auris and reduce the transmission of nosocomial infection.

Antifungal pipeline: Is there light at the end of the tunnel?

The misuse and overuse of classic antifungals have accelerated the development of resistance mechanisms, diminishing the efficacy of established therapeutic pathways and necessitating a shift towards alternative targets. Despite this pressing need for new treatments, the antifungal drug pipeline has been largely stagnant for the past three decades, primarily due to the high risks and costs associated with antifungal drug development, compounded by uncertain market returns. Extensive research durations, special patient populations and rigorous regulatory demands pose significant barriers to bringing novel antifungal agents to market. In response, the "push-pull" incentive model has emerged as a vital strategy to invigorate the pipeline and encourage innovation. This editorial critically examines the current clinical landscape and spotlights emerging antifungal agents, such as Fosmanogepix, Ibrexafungerp, and Olorofim, while also unraveling the multifaceted challenges faced in new antifungal drug development. The generation of novel antifungals offers a beacon of hope in the battle against antimicrobial resistance, but it is premature to declare them as definitive solutions. Their future role hinges on thorough clinical validation, cost-effectiveness assessments, and continuous post-marketing surveillance. Only through strategic implementation and integration with market strategies we can transform the landscape of antifungal development, addressing both the resistance crisis and the treatment challenges.

A novel diterpenic derivative produced by Streptomyces chrestomyceticus ADP4 is a potent inhibitor of biofilm and virulence factors in Candida albicans and C. auris

AIM

Isolation, identification, structural and functional characterization of potent anti-Candida compound with specific antagonistic activities against significant human pathogens, Candida albicans and C. auris.

METHODS AND RESULTS

The compound (55B3) was purified from the metabolites produced by Streptomyces chrestomyceticus ADP4 by employing column chromatography. The structure of 55B3 was determined from the analyses of spectral data that included LCMS, nuclear magnetic resonance, FTIR, and UV spectroscopies. It was identified as a novel derivative of diterpenic aromatic acid, 3-(dictyotin-11'-oate-15'α, 19'β-olide)-4-(dictyotin-11'-oate-15″α, 19″β-olide)-protocatechoic acid. The compound displayed potent antifungal and anti-biofilm activities against C. albicans ATCC 10231 (Minimum Inhibitory Concentration, MIC90:14.94 ± 0.17 μgmL-1 and MBIC90: 16.03 ± 1.1 μgmL-1) and against C. auris CBS 12372 (MIC90: 21.75 ± 1.5 μgmL-1 and Minimum Biofilm Inhibitory Concentration, MBIC90: 18.38 ± 1.78 μgmL-1). Further, pronounced inhibition of important virulence attributes of Candida spp., e.g. yeast-to-hyphae transition, secretory aspartyl proteinase and phospholipase B by 55B3 was noted at subinhibitory concentrations. A plausible mechanism of anti-Candida action of the compound appeared to be the inhibition of ergosterol biosynthesis, which was inhibited by 64 ± 3% at the MIC90 value. The non-cytotoxic attribute of the compound was noted in the liver cell line (HepG2 cells).

CONCLUSION

The present work led to the discovery of a novel diterpenic derivative produced by S. chrestomyceticus ADP4. The compound displayed potent anti-Candida activity, particularly against the two most significant human pathogens, C. albicans and C. auris, which underlined its significance as a potential drug candidate for infections involving these pathogens.

The Light-activated Effect of Natural Anthraquinone Parietin against Candida auris and Other Fungal Priority Pathogens

Antimicrobial photodynamic therapy (aPDT) is an evolving treatment strategy against human pathogenic microbes such as the Candida species, including the emerging pathogen C. auris. Using a modified EUCAST protocol, the light-enhanced antifungal activity of the natural compound parietin was explored. The photoactivity was evaluated against three separate strains of five yeasts, and its molecular mode of action was analysed via several techniques, i.e., cellular uptake, reactive electrophilic species (RES), and singlet oxygen yield. Under experimental conditions (λ = 428 nm, H = 30 J/cm2, PI = 30 min), microbial growth was inhibited by more than 90% at parietin concentrations as low as c = 0.156 mg/L (0.55 µM) for C. tropicalis and Cryptococcus neoformans, c = 0.313 mg/L (1.10 µM) for C. auris, c = 0.625 mg/L (2.20 µM) for C. glabrata, and c = 1.250 mg/L (4.40 µM) for C. albicans. Mode-of-action analysis demonstrated fungicidal activity. Parietin targets the cell membrane and induces cell death via ROS-mediated lipid peroxidation after light irradiation. In summary, parietin exhibits light-enhanced fungicidal activity against all Candida species tested (including C. auris) and Cryptococcus neoformans, covering three of the four critical threats on the WHO's most recent fungal priority list.

Candida auris in Greek healthcare facilities: Active surveillance results on first cases and outbreaks from eleven hospitals within Attica region

BACKGROUND

Candida auris was sporadically detected in Greece until 2019. Thereupon, there has been an increase in isolations among inpatients of healthcare facilities.

AIM

We aim to report active surveillance data on MALDI-TOF confirmed Candida auris cases and outbreaks, from November 2019 to September 2021.

METHODS

A retrospective study on hospital-based Candida auris data, over a 23-month period was conducted, involving 11 hospitals within Attica region. Antifungal susceptibility testing and genotyping were conducted. Case mortality and fatality rates were calculated and p-values less than 0.05 were considered statistically significant. Infection control measures were enforced and enhanced.

RESULTS

Twenty cases with invasive infection and 25 colonized were identified (median age: 72 years), all admitted to hospitals for reasons other than fungal infections. Median hospitalisation time until diagnosis was 26 days. Common risk factors among cases were the presence of indwelling devices (91.1 %), concurrent bacterial infections during hospitalisation (60.0 %), multiple antimicrobial drug treatment courses prior to hospitalisation (57.8 %), and admission in the ICU (44.4 %). Overall mortality rate was 53 %, after a median of 41.5 hospitalisation days. Resistance to fluconazole and amphotericin B was identified in 100 % and 3 % of tested clinical isolates, respectively. All isolates belonged to South Asian clade I. Outbreaks were identified in six hospitals, while remaining hospitals detected sporadic C. auris cases.

CONCLUSION

Candida auris has proven its ability to rapidly spread and persist among inpatients and environment of healthcare facilities. Surveillance focused on the presence of risk factors and local epidemiology, and implementation of strict infection control measures remain the most useful interventions.

Recurrent Fungemia Due to Candida auris

We present a case of recurrent multidrug-resistant Candida auris (C. auris) in a patient who required multiple hospitalizations. The patient's case was complicated by interval admissions to the intensive care unit for septic and hypovolemic shock for 12 months to manage C. auris fungemia. Despite adequate isolation precautions and appropriate antifungal treatment, this case demonstrates the profound implications of this emerging pathogen, specifically regarding invasive infections. Moreover, C. auris is rapidly becoming known as a multidrug-resistant organism, which limits treatment options and thus contributes to high mortality.

In Vitro Activitiy of Rezafungin in Comparison with Anidulafungin and Caspofungin against Invasive Fungal Isolates (2017 to 2022) in China

The efficacy of different echinocandins is assessed by evaluating the in vitro activity of a novel antifungal, rezafungin, against invasive fungal isolates in comparison with anidulafungin and caspofungin. Using the broth microdilution (BMD) method, the susceptibility of 1000 clinical Candida isolates (including 400 C. albicans, 200 C. glabrata, 200 C. parapsilosis, 150 C. tropicalis and 50 C. krusei) and 150 Aspergillus isolates (100 A. fumigatus and 50 A. flavus) from the Eastern China Invasive Fungi Infection Group (ECIFIG) was tested for the antifungals including anidulafungin, rezafungin, caspofungin and fluconazole. The echinocandins showed strong activity against C. albicans that was maintained against fluconazole-resistant isolates. The GM MIC (geometric mean minimum inhibitory concentration) value of rezafungin was found to be comparable to that of anidulafungin or caspofungin against the five tested common Candida species. C. tropicalis exhibited higher resistance rates (about 8.67-40.67% in different antifungals) than the other four Candida species. Through the sequencing of FKS genes, we searched for mutations in echinocandin-resistant C. tropicalis isolates and found that all displayed alterations in FKS1 S654P. The determined MEC (minimal effective concentration) values against A. fumigatus and A. flavus for rezafungin (0.116 μg/mL, 0.110 μg/mL) are comparable to those of caspofungin (0.122 μg/mL, 0.142 μg/mL) but higher than for anidulafungin (0.064 μg/mL, 0.059 μg/mL). Thus, the in vitro activity of rezafungin appears comparable to anidulafungin and caspofungin against most common Candida and Aspergillus species. Rezafungin showed higher susceptibility rates against C. glabrata. Rezafungin indicates its potent activity for potential clinical application.

Malik A, Nafady-Hego H, Hanana F, Abraham J, G. Garcell H, Hudaib G, Al-Wali W, Eltayeb F, Shams S, G. Thomas A, Saleem S, Abou-Samra AB, Butt AA. Spectrum of infection and outcomes in individuals with Candida auris infection in Qatar

BACKGROUND

We investigated the spectrum of infection and risk factors for invasive fungal disease due to Candida auris (CA) in Qatar.

METHODS

We performed structured chart reviews on individuals with any positive CA culture between May 2019 and December 2022 at three tertiary care hospitals in Qatar. Invasive CA disease (ICAD) was defined as a positive sterile site culture, or any positive culture for CA with appropriate antifungal prescription. Main outcomes included proportion of individuals who developed ICAD among those with positive cultures, and 30-day/in-hospital mortality.

RESULTS

Among 331 eligible individuals, median age was 56 years, 83.1% were male, 70.7% were non-Qataris, and 37.5% had ≥ 3 comorbidities at baseline. Overall, 86.4% were deemed to have colonization and 13.6% developed ICAD. Those with ICAD were more likely to have invasive central venous or urinary catheterization and mechanical ventilation. Individuals with ICAD had longer prior ICU stay (16 vs 26 days, P = 0.002), and longer hospital length of stay (63 vs. 43 days; P = 0.003), and higher 30-day mortality (38% vs. 14%; P<0.001). In multivariable regression analysis, only mechanical ventilation was associated with a higher risk of ICAD (OR 3.33, 95% CI 1.09-10.17).

CONCLUSION

Invasive Candida auris Disease is associated with longer hospital stay and higher mortality. Severely ill persons on mechanical ventilation should be especially monitored for development of ICAD.

Assessing Diagnosis of Candida Infections: A Study on Species Prevalence and Antifungal Resistance in Northern Morocco

The incidence of Candida infections has increased in the last decade, posing a serious threat to public health. Appropriately facing this challenge requires precise epidemiological data on species and antimicrobial resistance incidence, but many countries lack appropriate surveillance programs. This study aims to bridge this gap for Morocco by identifying and phenotyping a year-long collection of clinical isolates (n = 93) from four clinics in Tetouan. We compared the current standard in species identification with molecular methods and assessed susceptibility to fluconazole and anidulafungin. Our results identified limitations in currently used diagnostics approaches, and revealed that C. albicans ranks as the most prevalent species with 60 strains (64.52%), followed by C. glabrata with 14 (15.05%), C. parapsilosis with 6 (6.45%), and C. tropicalis with 4 (4.30%). In addition, we report the first identification of C. metapsilosis in Morocco. Susceptibility results for fluconazole revealed that some isolates were approaching MICs resistance breakpoints in C. albicans (2), and C. glabrata (1). Our study also identified anidulafungin resistant strains in C. albicans (1), C. tropicalis (1), and C. krusei (2), rendering the two strains from the latter species multidrug-resistant due to their innate resistance to fluconazole. These results raise concerns about species identification and antifungal resistance in Morocco and highlight the urgent need for more accurate methods and preventive strategies to combat fungal infections in the country.

Rapid Environmental Contamination With Candida auris and Multidrug-Resistant Bacterial Pathogens Near Colonized Patients

BACKGROUND

Environmental contamination is suspected to play an important role in Candida auris transmission. Understanding speed and risks of contamination after room disinfection could inform environmental cleaning recommendations.

METHODS

We conducted a prospective multicenter study of environmental contamination associated with C. auris colonization at 6 ventilator-capable skilled nursing facilities and 1 acute care hospital in Illinois and California. Known C. auris carriers were sampled at 5 body sites followed by sampling of nearby room surfaces before disinfection and at 0, 4, 8, and 12 hours after disinfection. Samples were cultured for C. auris and bacterial multidrug-resistant organisms (MDROs). Odds of surface contamination after disinfection were analyzed using multilevel generalized estimating equations.

RESULTS

Among 41 known C. auris carriers, colonization was detected most frequently on palms/fingertips (76%) and nares (71%). C. auris contamination was detected on 32.2% (66/205) of room surfaces before disinfection and 20.5% (39/190) of room surfaces by 4 hours after disinfection. A higher number of C. auris-colonized body sites was associated with higher odds of environmental contamination at every time point following disinfection, adjusting for facility of residence. In the rooms of 38 (93%) C. auris carriers co-colonized with a bacterial MDRO, 2%-24% of surfaces were additionally contaminated with the same MDRO by 4 hours after disinfection.

CONCLUSIONS

C. auris can contaminate the healthcare environment rapidly after disinfection, highlighting the challenges associated with environmental disinfection. Future research should investigate long-acting disinfectants, antimicrobial surfaces, and more effective patient skin antisepsis to reduce the environmental reservoir of C. auris and bacterial MDROs in healthcare settings.

In silico genome wide identification of long non-coding RNAs differentially expressed during Candida auris host pathogenesis

Candida auris is an invasive fungal pathogen of high concern due to acquired drug tolerance against antifungals used in clinics. The prolonged persistence on biotic and abiotic surfaces can result in onset of hospital outbreaks causing serious health threat. An in depth understanding of pathology of C. auris is highly desirable for development of efficient therapeutics. Non-coding RNAs play crucial role in fungal pathology. However, the information about ncRNAs is scanty to be utilized. Herein our aim is to identify long noncoding RNAs with potent role in pathobiology of C. auris. Thereby, we analyzed the transcriptomics data of C. auris infection in blood for identification of potential lncRNAs with regulatory role in determining invasion, survival or drug tolerance under infection conditions. Interestingly, we found 275 lncRNAs, out of which 253 matched with lncRNAs reported in Candidamine, corroborating for our accurate data analysis pipeline. Nevertheless, we obtained 23 novel lncRNAs not reported earlier. Three lncRNAs were found to be under expressed throughout the course of infection, in the transcriptomics data. 16 of potent lncRNAs were found to be coexpressed with coding genes, emphasizing for their functional role. Noteworthy, these ncRNAs are expressed from intergenic regions of the genes associated with transporters, metabolism, cell wall biogenesis. This study recommends for possible association between lncRNA expression and C. auris pathogenesis.

Potential Environmental Reservoirs of Candida auris: A Systematic Review

Candida auris, a multidrug-resistant yeast, poses significant challenges in healthcare settings worldwide. Understanding its environmental reservoirs is crucial for effective control strategies. This systematic review aimed to review the literature regarding the natural and environmental reservoirs of C. auris. Following the PRISMA guidelines, published studies until October 2023 were searched in three databases: PubMed, Web of Science, and Scopus. Information regarding the origin, sampling procedure, methods for laboratory identification, and antifungal susceptibility was collected and analyzed. Thirty-three studies published between 2016 and 2023 in 15 countries were included and analyzed. C. auris was detected in various environments, including wastewater treatment plants, hospital patient care surfaces, and natural environments such as salt marshes, sand, seawater, estuaries, apples, and dogs. Detection methods varied, with molecular techniques often used alongside culture. Susceptibility profiles revealed resistance patterns. Phylogenetic studies highlight the potential of environmental strains to influence clinical infections. Despite methodological heterogeneity, this review provides valuable information for future research and highlights the need for standardized sampling and detection protocols to mitigate C. auris transmission.

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.

Identification of the Most Immunoreactive Antigens of Candida auris to IgGs from Systemic Infections in Mice

The delay in making a correct diagnosis of Candida auris causes concern in the healthcare system setting, and immunoproteomics studies are important to identify immunoreactive proteins for new diagnostic strategies. In this study, immunocompetent murine systemic infections caused by non-aggregative and aggregative phenotypes of C. auris and by Candida albicans and Candida haemulonii were carried out, and the obtained sera were used to study their immunoreactivity against C. auris proteins. The results showed higher virulence, in terms of infection signs, weight loss, and histopathological damage, of the non-aggregative isolate. Moreover, C. auris was less virulent than C. albicans but more than C. haemulonii. Regarding the immunoproteomics study, 13 spots recognized by sera from mice infected with both C. auris phenotypes and analyzed by mass spectrometry corresponded to enolase, phosphoglycerate kinase, glyceraldehyde-3-phosphate dehydrogenase, and phosphoglycerate mutase. These four proteins were also recognized by sera obtained from human patients with disseminated C. auris infection but not by sera obtained from mice infected with C. albicans or Aspergillus fumigatus. Spot identification data are available via ProteomeXchange with the identifier PXD049077. In conclusion, this study showed that the identified proteins could be potential candidates to be studied as new diagnostic or even therapeutic targets for C. auris.

Candida auris Outbreaks: Current Status and Future Perspectives

Candida auris has been identified by the World Health Organization (WHO) as a critical priority pathogen on its latest list of fungi. C. auris infections are reported in the bloodstream and less commonly in the cerebrospinal fluid and abdomen, with mortality rates that range between 30% and 72%. However, no large-scale epidemiology studies have been reported until now. The diagnosis of C. auris infections can be challenging, particularly when employing conventional techniques. This can impede the early detection of outbreaks and the implementation of appropriate control measures. The yeast can easily spread between patients and in healthcare settings through contaminated environments or equipment, where it can survive for extended periods. Therefore, it would be desirable to screen patients for C. auris colonisation. This would allow facilities to identify patients with the disease and take appropriate prevention and control measures. It is frequently unsusceptible to drugs, with varying patterns of resistance observed among clades and geographical regions. This review provides updates on C. auris, including epidemiology, clinical characteristics, genomic analysis, evolution, colonisation, infection, identification, resistance profiles, therapeutic options, prevention, and control.

Purification and characterization of Cdr1, the drug-efflux pump conferring azole resistance in Candida species

Candida albicans and C. glabrata express exporters of the ATP-binding cassette (ABC) superfamily and address them to their plasma membrane to expel azole antifungals, which cancels out their action and allows the yeast to become multidrug resistant (MDR). In a way to understand this mechanism of defense, we describe the purification and characterization of Cdr1, the membrane ABC exporter mainly responsible for such phenotype in both species. Cdr1 proteins were functionally expressed in the baker yeast, tagged at their C-terminal end with either a His-tag for the glabrata version, cgCdr1-His, or a green fluorescent protein (GFP) preceded by a proteolytic cleavage site for the albicans version, caCdr1-P-GFP. A membrane Cdr1-enriched fraction was then prepared to assay several detergents and stabilizers, probing their level of extraction and the ATPase activity of the proteins as a functional marker. Immobilized metal-affinity and size-exclusion chromatographies (IMAC, SEC) were then carried out to isolate homogenous samples. Overall, our data show that although topologically and phylogenetically close, both proteins display quite distinct behaviors during the extraction and purification steps, and qualify cgCdr1 as a good candidate to characterize this type of proteins for developing future inhibitors of their azole antifungal efflux activity.