Worldwide emergence of fluconazole-resistant Candida parapsilosis: current framework and future research roadmap

Screening a 681-membered yeast collection for the secretion of proteins with antifungal activity

Fungal pathogens pose a threat to human health and food security. Few antifungals are available and resistance to all has been reported. Novel strategies to control plant and human pathogens as well as food spoilers are urgently required. Environmental yeasts provide a functionally diverse, yet underexploited potential for fungal control based on their natural competition via the secretion of proteins and other small molecules such as iron chelators, volatile organic compounds or biosurfactants. However, there is a lack of standardized workflows to systematically access application-relevant yeast-based compounds and understand their molecular functioning. Towards this goal, we developed a workflow to identify and characterize yeast isolates that are active against spoilage yeasts and relevant human and plant pathogens, herein focusing on discovering yeasts that secrete antifungal proteins. The workflow includes the classification of the secreted molecules and cross-comparison of their antifungal capacity using an independent synthetic calibrant. Our workflow delivered a collection of 681 yeasts of which 212 isolates (31 %) displayed antagonism against at least one target strain. While 57.5 % of the active yeasts showed iron-depended antagonism, likely due to pulcherrimin-like iron chelators, 31.7 % secreted antifungal proteins. Those yeast candidates clustered within twelve OTUs, showed narrow and broad target spectra, and several showed a broad pH and temperature activity profile. Given the tools for yeast biotechnology and protein engineering available, our collection can serve as a rich starting point for genetic and molecular characterization of the various antifungal phenotypes, their mode of action and their future exploitation.

Distribution and prevalence of fungemia: a five-year retrospective multicentric survey in Venetian region, Italy

Background

Invasive fungal infections, significantly impact hospitalized and immunocompromised populations. Recent trends showed a shift from Candida albicans to non-albicans Candida (NAC) species, raising concerns about antifungal resistance.

Objectives

Our study focuses on the distribution of fungal species in blood cultures obtained from different healthcare settings, including hospitals, long-term care facilities, and community health centers in the Venetian region of Italy.

Methods

We retrospectively analyzed all consecutive blood culture isolates across 5 hospitals, 38 long-term care facilities, and 24 sample collection centers (blood exams and culture) from 2019 to 2023.

Results

Between 2019 and 2023, 11,552 microorganisms were isolated from blood cultures; 693 (6.0%) were fungi. The yearly prevalence ranged from 5.2% in 2019 to 6.1% in 2023. C. albicans isolates decreased significantly, from 60.0% in 2019 to 43.1% in 2023. NAC species showed significant growth, particularly C. parapsilosis sensu stricto (from 23.6% in 2019 to 28.8% in 2023), C. tropicalis (from 0.0% in 2019 to 7.2% in 2023), and N. glabratus (from 9.1% in 2019 to 11.8% in 2023). Medical wards consistently recorded the highest number of cases (429/693, 61.9%), with C. albicans predominating in earlier years. Resistance to amphotericin B rose sharply in C. parapsilosis ss. (22.5% in 2022), while fluconazole resistance in N. glabratus remained high (peaking at 85.7% in 2021).

Conclusion

The increasing dominance of NAC species and rising resistance trends underscore the necessity for enhanced diagnostics, infection prevention, and antifungal stewardship. Future research should incorporate clinical data to optimize fungemia management strategies.

Impact of Fluconazole Resistance on the Outcomes of Patients With Candida parapsilosis Bloodstream Infections: A Retrospective Multicenter Study

BACKGROUND

This study assesses the impact of fluconazole resistance on 30-day all-cause mortality and 1-year recurrence in patients with Candida parapsilosis bloodstream infections (BSI).

METHODS

A multicenter retrospective study was performed at 3 hospitals in Italy and Spain between 2018 and 2022. Adult patients with positive blood cultures for C. parapsilosis who received appropriate targeted therapy with either echinocandins or fluconazole were included.

RESULTS

Among 457 patients, 196 (42.9%) had fluconazole-resistant C. parapsilosis (FLZR-CP) BSI and 261 (57.1%) had fluconazole-susceptible C. parapsilosis (FLZS-CP) BSI. All FLZR-CP patients received targeted echinocandins, while FLZS-CP patients received either echinocandins (60.5%) or fluconazole (39.5%). Unadjusted 30-day all-cause mortality rates were 28.6% for FLZR-CP and 28.4% for FLZS-CP (log-rank test, P = .998). In multivariable analysis, increased mortality was associated with age (adjusted hazard ratio [aHR] 1.03 per year; 95% confidence interval [CI], 1.01-1.05; P = .0005), solid tumor (aHR 1.91; 95% CI, 1.06-3.46; P = .0302), previous antifungal treatment (aHR 1.84; 95% CI, 1.12-3.10; P = .0192), and septic shock (aHR 2.39; 95% CI, 1.42-4.06; P = .0010), but not fluconazole resistance (aHR 1.00; 95% CI, .62-1.63; P = .9864) nor the type of initial antifungal therapy (aHR 1.46; 95% CI, .69-3.06; P = .3202). Propensity score-matched analysis showed no 30-day all-cause mortality difference between echinocandin-treated FLZR-CP and fluconazole-treated FLZS-CP patients (HR 0.81; 95% CI, .37-1.75; P = .5915). However, a higher 1-year recurrence risk was observed in FLZR-CP patients (odds ratio, 7.37; 95% CI, 2.11-25.80; P = .0018).

CONCLUSIONS

Our results suggest that fluconazole resistance is not associated with a higher mortality risk in patients with C. parapsilosis BSI, though 1-year recurrence rates were higher in the FLZR-CP group.

An Update on Fungal Disease Outbreaks of Public Health Concern

For this narrative review, we describe recent high-profile and severe outbreaks of emerging fungal infections, emphasizing lessons learned and opportunities to improve future prevention and response efforts. Several themes and challenges remain consistent across a diverse array of fungal outbreaks, including the multidisciplinary need for improved diagnostic testing to determine species and perform antifungal susceptibility testing, clinical awareness, and optimization of antifungal use. Recent outbreaks exemplify the growing promise of non-culture-based tools in identifying fungal outbreaks and improving responses, although access remains limited. Culture-based tools remain critical for performing antifungal-susceptibility to guide therapy.

Invasive Candidiasis

Invasive candidiasis (IC) is a term that refers to a group of infectious syndromes caused by a variety of Candida species, 6 of which cause the vast majority of cases globally. Candidemia is probably the most commonly recognized syndrome associated with IC; however, Candida species can cause invasive infection of any organ, especially visceral organs, vasculature, bones and joints, eyes, and central nervous system. The optimal use of these newer diagnostics coupled with a thoughtful clinical assessment of at-risk patients and the judicious use of effective antifungal therapy is a key to achieving good antifungal stewardship and improved patient outcomes.

Infectious complications and the utility of serum and cellular markers of infections in the setting of allogeneic hematopoietic stem cell transplantation

INTRODUCTION

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients are severely immunocompromised and susceptible to bacterial, viral, and fungal infections. Despite improved anti-microbial prophylaxis and preemptive strategies, bacterial bloodstream infections (BSIs) occur frequently in allo-HSCT recipients and are associated with increased morbidity and mortality. Cytomegalovirus (CMV) and Epstein Barr virus (EBV) are the most relevant viruses following allo-HSCT and remain major concerns. Fungal infections, including those caused by Candida and Aspergillus species, are persistent and feared complications.

AREAS COVERED

We aim to provide clinicians caring for allo-HSCT recipients with a comprehensive overview of the risk factors that predispose patients to common bacterial, fungal, and viral infections during the first years post-transplant. The focus is on the value of noninvasive diagnostic biomarkers and serological assays in enhancing the early detection and management of these infections.

EXPERT OPINION

Effective management of infectious complications following allo-HSCT relies on continuous immune recovery monitoring and the implementation of advanced diagnostic methods. Utilizing noninvasive diagnostic methods is crucial for early detection and different intervention strategies. The development and integration of reliable microbiological markers into clinical practice is essential for enhancing patient outcomes and mitigating infection-related risks. Emphasizing diagnostic innovation will be pivotal in advancing patient care post-allo-HSCT.

Polydimethylsiloxane loaded capsaicin afflicts membrane integrity, metabolic activity and biofilm formation of nosocomial pathogens

Biofilms constitute 80 % of all nosocomial infections associated with invasive medical devices. Polydimethylsiloxane, a highly elastic, inert, non-reactive, biocompatible silicone polymer is widely used as implant biomaterial due to its non-toxic and low-immunogenic nature. Owing to its hydrophobicity, PDMS suffers from microbial adhesion. Inhibition of biofilm formation on PDMS surfaces is imperative to prevent morbidity, mortality and replacement of implants. The present study investigates the efficacy of capsaicin (0.5 % w/v) loaded PDMS as a broad spectrum antimicrobial surface against Staphylococcus aureus, Escherichia coli and Candida albicans. Capsaicin exhibited minimum inhibitory concentration of 1024 μg mL-1 for S. aureus, E. coli and 256 μg mL-1 for C. albicans. Capsaicin inhibited biofilms of S. aureus, E. coli and C. albicans at much lower concentrations of 2, 64 and 8 μg mL-1 respectively. The minimum capsaicin concentrations required for total biofilm eradication was found to be 256, 512, 128 μg mL-1 for S. aureus, E. coli and C. albicans respectively. Probing sub-lethal concentrations of capsaicin revealed 38, 32, 30 % reduction in metabolic activity of S. aureus, E. coli & C. albicans planktonic cells respectively. Similarly, there was an increase in permeability of cells to propidium iodide compared to control. By reducing the metabolic activity and perturbing membrane integrity, capsaicin could prevent biofilm formation and this was also observed with capsaicin-PDMS surfaces that exhibited 1 log (∼90 %) reduction of viable bacterial counts.

Pathogenic Aspergillus spp. and Candida spp. in coastal waters from southern Brazil: an one health approach

Aspergillus and Candida are ubiquitous fungi included in the group of high priority in the World Health Organization list of fungal pathogens. They are found in various ecosystems and the environmental role in increasing the resistance to antifungals has been shown. Thus, we aimed to determine the occurrence of Aspergillus spp. and Candida spp. pathogenic species in water samples from a coastal ecosystem from southern Brazil, and its antifungal susceptibility profile. Water samples were collected monthly at three environmental sites, over 25 months. Abiotic parameters of the water samples were analyzed as well as antifungal susceptibility. Aspergillus spp. and Candida spp. were detected in 44% (n = 33/75) and 40% (n = 30/75) respectively of the samples, totaling 67 and 96 isolates. Section Fumigati and C. parapsilosis were the most section/species isolated. Triazole resistance was detected in 3% of the Aspergillus spp. (2/67) and in 1% of the Candida spp. (1/96) isolates. Our study contributes with data showing that coastal aquatic environments can serve as a source of infection of resistant fungal isolates, proving the need for environmental surveillance and monitoring of fungal resistance in the One Health perspective.

Rezafungin in special populations with candidaemia and/or invasive candidiasis

Achieving and maintaining therapeutic drug exposures with antifungals can be challenging in special patient populations, such as those with organ dysfunction (liver or kidney) or obesity, or elderly patients, due to dose-exposure relationships and potential drug-drug interactions. Dose adjustments may be needed in these populations to maintain therapeutic efficacy and/or prevent toxicity. We reviewed specific dosing considerations for antifungals in special populations with candidaemia and/or invasive candidiasis, focusing on those relating to echinocandins (based on prescribing information), and then explored the utility of the second-generation echinocandin rezafungin in treating these populations (based on currently available data identified from a PubMed and congress abstract search). Available data showed that echinocandins may sometimes require dosing modifications for special populations with candidaemia/invasive candidiasis, primarily due to decreases in pharmacokinetic exposures. Rezafungin appears to be suitable for use in a variety of special populations without the need for dose modifications based on available data, including patients with organ dysfunction or obesity, and elderly and critically ill patients. Further research is needed in populations where rezafungin data are not available including children, people living with HIV, patients receiving extracorporeal membrane oxygenation and those with underlying neurological conditions.

Fluconazole induces cardiovascular toxicity in zebrafish by promoting oxidative stress, apoptosis, and disruption of key developmental genes

This study systematically evaluated the toxic effects of fluconazole on the cardiovascular development of zebrafish. Zebrafish embryos were treated with different concentrations of fluconazole (200, 400, and 800 μg/ml) to observe its impact on heart development, reactive oxygen species (ROS) generation, apoptosis, and hemoglobin production. The results showed that as the concentration of fluconazole increased, significant changes in zebrafish heart structure were observed, along with a notable reduction in heart rate. Pericardial edema and cardiac morphological abnormalities were particularly prominent in the high-dose group. In addition, fluconazole treatment significantly increased ROS levels and induced apoptosis in cardiac cells. Enzyme-linked immunosorbent assay (ELISA) results showed that fluconazole treatment significantly increased the malondialdehyde (MDA) content and reduced superoxide dismutase (SOD) and catalase (CAT) activity, suggesting that oxidative stress and cell death may play a key role in its cardiotoxicity. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis revealed that fluconazole treatment significantly affected the expression of several key genes related to heart development and function, particularly cardiac myosin light chain 2 (cmlc2), ventricular myosin heavy chain (vmhc), and myosin heavy chain 6 (myh6), whose expression changes were closely associated with alterations in heart morphology and function. Transcriptomic analysis showed that several signaling pathways related to cardiac development, apoptosis, and metabolism were affected. In summary, this study reveals the multifaceted cardiotoxic mechanisms of fluconazole in zebrafish and provides new insights into drug safety assessment.

Environmental Fate of the Azole Fungicide Fluconazole and Its Persistent and Mobile Transformation Product 1,2,4-Triazole

Fluconazole is a persistent and mobile pharmaceutical azole fungicide observed in natural waters globally. It does not significantly degrade via traditional wastewater treatment, resulting in likely environmental and human exposure and environmental-origin azole fungicide resistance. Indirect photochemistry is known to degrade many recalcitrant contaminants in natural waters but has not been tested for fluconazole. We systematically measured rates and identified products of the indirect photodegradation of fluconazole in genuine and synthetic surface waters with varying nitrate, bicarbonate, and dissolved organic matter using high resolution mass spectrometry. Degradation half-lives of fluconazole ranged from 2 weeks to a year, indicating indirect photochemistry is slow but competitive with other loss processes. The transformation products 1,2,4-triazole and 1,2,4-triazole-1-acetic acid were produced in 30 to 100% yield during fluconazole degradation. These products are far more resistant to indirect photochemistry than fluconazole, with half-lives for 1,2,4-triazole in the environment of between 1 and 3 years when measurable with our methods. These "very persistent very mobile" contaminants are likely formed by most pharmaceutical and agrochemical azole fungicides, are regularly detected in the US and Denmark in monitoring programs and our exposure modeling demonstrates high potential for human exposure through drinking water with uncertain health implications.

Phenotypic and genotypic characterization of Candida parapsilosis complex isolates from a Lebanese hospital

The opportunistic pathogen Candida parapsilosis is a major causative agent of candidiasis leading to death in immunocompromised individuals. Azoles are the first line of defense in their treatment. The purpose of this study was to characterize eight fluconazole-resistant and sensitive C. parapsilosis hospital isolates through a battery of phenotypic tests that target pathogenicity attributes such as virulence, biofilm formation, stress resistance, and ergosterol content. Whole genome sequencing was carried out to identify mutations in key pathogenicity and resistance genes. Phylogenetic comparison was performed to determine strain relatedness and clonality. Genomic data and phylogenetic analysis revealed that two isolates were C. orthopsilosis and C. metapsilosis misidentified as C. parapsilosis. Whole genome sequencing analysis revealed known and novel mutations in key drug resistance and pathogenicity genes such as ALS6, ALS7, SAPP3, SAP7, SAP9, CDR1, ERG6, ERG11 and UPC2. Phylogenetic analysis revealed a high degree of relatedness and clonality within our C. parapsilosis isolates. Our results showed that resistant isolates exhibited an increase in biofilm content compared to the sensitive isolates. In conclusion, our study is the first of its kind in Lebanon to describe phenotypic and genotypic characteristics of nosocomial C. parapsilosis complex isolates having a remarkable ability to form biofilms.

Investigation of clonal relationship in hospital-associated Candida parapsilosis isolates

PURPOSE

We aimed to investigate the clonal relationship and antifungal susceptibility of C. parapsilosis isolated from hospitalized patients and to determine whether it is due to transmission or not and the spread status of resistant isolates.

METHODS

Between January 2017 and June 2019, totally 277 C parapsilosis isolated from blood, urine and catheter samples of adult or pediatric in-patient (intensive care and service) who applied to Mycology laboratory in our hospital were included in the study. All isolates were identified using conventional methods, API 20 C AUX (Biomerieux, France) semi-automated system and confirmed by MALDI-TOF MS Biotyper Smart (Bruker Daltonik GmbH, Germany). Randomly amplified polymorphic DNA (RAPD) PCR method was used for molecular genotyping of isolates. MIC values for fluconazole, anidulafungin and amphotericin B were determined according to the M27-A3 CLSI broth microdilution reference method guideline.

RESULTS

Seven different band patterns (A-G) were detected in 277 isolates by RAPD PCR method. According to the rank order of the isolates, 170 (61.37%) C, 65 (23.47%) A, 18 (6.50%) G, 11 (3.97%) B, six (2.17%) E, two (0.72%) F and one (0.36%) D patterns were determined. When the band patterns of the isolates were evaluated according to the years, it was detected that C pattern continued between 2017 and 2019 and that all isolates continued to spread only as C pattern in 2019. While 211 (76.17%) of the isolates were resistant to fluconazole (≥ 8 µg/ml), two (0.72%) were resistant to amphotericin B (≥ 2 µg/ml) and two (0.72%) were intermediate to anidulafungin.

CONCLUSIONS

It is noteworthy that the spread of the C pattern in C. parapsilosis strains has increased over the years and is the main pattern isolated from the whole hospital. The detection of high fluconazole resistance in C. parapsilosis isolates in our hospital may also be related to the dominant pattern.

Rapid Identification of Clinically Relevant Candida spp. by I-dOne Software Using Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) Spectroscopy

Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy is a spectrum-based technique that quantifies the absorption of infrared light by molecules present in the microbial cell. The aim of the present study was to evaluate the performance of the ATR-FTIR spectroscopic technique via I-dOne software (Version 2.0) compared with the MALDI-TOF MS in identifying Candida spp. Each infrared spectrum was compared with spectra stored in the software database. The updated version of the I-dOne software was used to analyze ATR-FTIR spectra. All Candida isolates 284/284 (100%) were classified correctly according to the genus. Overall species identification yielded 272/284 (95.8%) concordant identification results with MALDI-TOF MS. Additionally, all 79 isolates belonging to the Candida parapsilosis species complex were identified correctly to the species level with the updated version of the I-dOne software. Only 12 (4.2%) isolates were misidentified at the species level. The present study highlights the potential diagnostic performance of the I-dOne software with ATR-FTIR spectroscopic technique referral spectral database as a real alternative for routine identification of the most frequently isolated Candida spp.

Mechanisms of Azole Potentiation: Insights from Drug Repurposing Approaches

The emergence of azole resistance and tolerance in pathogenic fungi has emerged as a significant public health concern, emphasizing the urgency for innovative strategies to bolster the efficacy of azole-based treatments. Drug repurposing stands as a promising and practical avenue for advancing antifungal therapy, with the potential for swift clinical translation. This review offers a comprehensive overview of azole synergistic agents uncovered through drug repurposing strategies, alongside an in-depth exploration of the mechanisms by which these agents augment azole potency. Drawing from these mechanisms, we delineate strategies aimed at enhancing azole effectiveness, such as inhibiting efflux pumps to elevate azole concentrations within fungal cells, intensifying ergosterol synthesis inhibition, mitigating fungal cell resistance to azoles, and disrupting biological processes extending beyond ergosterol synthesis. This review is beneficial for the development of these potentiators, as it meticulously examines instances and provides nuanced discussions on the mechanisms underlying the progression of azole potentiators through drug repurposing strategies.

Invasive fungal disease in the immunocompromised host: changing epidemiology, new antifungal therapies, and management challenges

BACKGROUND

Invasive fungal disease (IFD) causes morbidity and mortality in immunocompromised hosts (ICHs). Based on increasing recognition of the impact of IFD on human disease, a recent WHO priority list identified key areas of need.

OBJECTIVES

This review examines changes in the epidemiology of IFD, in particular the emergence of antifungal-resistant pathogens and the current availability of rapid diagnostic tests and antifungal treatment options.

SOURCES

Literature between 2000 and January 2024 regarding fungal epidemiology, diagnostic tests, antifungal resistance, emerging fungal pathogens, and novel antifungal agents in both adult and paediatric ICH were reviewed.

CONTENT

We describe the changing epidemiology and continued burden and mortality of IFD in ICH. Furthermore, we discuss the emergence of antifungal-resistant organisms driven by new immunosuppressed populations, climate change, and antifungal exposure in the individual and environment. We highlight novel antifungal agents and how they will address current unmet needs.

IMPLICATIONS

The changing epidemiology and increased population at risk for IFD, lack of recognition or quantification of risks for IFD with new therapies, current gaps in the availability of rapid diagnostic tests, and the imminent availability of novel antifungals with distinct spectra of activity argue for improved availability of and access to rapid diagnostics, antifungal stewardship programmes, and global access to antifungal agents.

Insights into the origin, hybridisation and adaptation of Candida metapsilosis hybrid pathogens

Hybridisation is a source of genetic diversity, can drive adaptation to new niches and has been found to be a frequent event in lineages harbouring pathogenic fungi. However, little is known about the genomic implications of hybridisation nor its impact on pathogenicity-related traits. A common limitation for addressing these questions is the narrow representativity of sequenced genomes, mostly corresponding to strains isolated from infected patients. The opportunistic human pathogen Candida metapsilosis is a hybrid that descends from the crossing between unknown parental lineages. Here, we sequenced the genomes of five new C. metapsilosis isolates, one representing the first African isolate for this species, and four environmental isolates from marine niches. Our comparative genomic analyses, including a total of 29 sequenced strains, shed light on the phylogenetic relationships between C. metapsilosis hybrid isolates and show that environmental strains are closely related to clinical ones and belong to different clades, suggesting multiple independent colonisations. Furthermore, we identify a new diverging clade likely emerging from the same hybridisation event that originated two other previously described hybrid clades. Lastly, we evaluate phenotypes relevant during infection such as drug susceptibility, thermotolerance or virulence. We identify low drug susceptibility phenotypes which we suggest might be driven by loss of heterozygosity events in key genes. We discover that thermotolerance is mainly clade-dependent and find a correlation with the faecal origin of some strains which highlights the adaptive potential of the fungus as commensal.

Nanoceria Anti-inflammatory and Antimicrobial Nanodrug: Cellular and Molecular Mechanism of Action

INTRODUCTION

Nanoceria is a well-known nanomaterial with various properties, including antioxidant, proangiogenic, and therapeutic effects. Despite its potential, there are still aspects that require further exploration, particularly its anti-inflammatory and antimicrobial activities.

METHODS

The global demand for novel anti-inflammatory and antimicrobial drugs underscores the significance of understanding nanoceria in both contexts. In this study, we evaluated the effect of nanoceria on macrophage polarization to better understand its anti-inflammatory effects. Additionally, we investigated the mechanism of action of nanoceria against Cryptococcus neoformans (ATCC 32045), Candida parapsilosis (ATCC 22019), Candida krusei (ATCC 6258), and Candida albicans.

RESULTS

The results demonstrated that nanoceria can polarize macrophages toward an anti-inflammatory profile, revealing the cellular mechanisms involved in the anti-inflammatory response. Concerning the antimicrobial effect, it was observed that nanoceria have a more pronounced impact on Candida parapsilosis, leading to the formation of pronounced pores on the surface of this species.

CONCLUSION

Finally, biochemical analysis revealed transitory alterations, mainly in liver enzymes. The data support the use of nanoceria as a potential anti-inflammatory and antimicrobial drug and elucidate some of the mechanisms involved, shedding light on the properties of this nanodrug.

Antifungal potential of silver nanoparticles stabilized with the flavonoid naringenin

Introduction. Fungal infections caused by yeast have increased in recent decades, becoming a major threat to public health.Hypothesis/Gap Statement. Antifungal therapy represents a challenging problem because, in addition to presenting many side effects, fungal resistance has been increasing in recent years. As a result, the search for new therapeutic agents has advanced with the use of new technologies such as nanoparticles (NPs).Aim. Synthesize, characterize and evaluate the antifungal potential of naringenin (NAR)-stabilized silver NPs.Methodology. The biosynthesis of NPs was stabilized using the NAR molecule and an aqueous solution of silver nitrate. The characterization of silver nanoparticles (AgNPs) was performed using different methods, which include UV-visible spectroscopy, powder X-ray diffraction (XRD), transmission electron microscopy, zeta potential measurements and Fourier transform infrared (FTIR) spectroscopy. Antifungal activity was evaluated against clinical isolates of Candida albicans by determining the MIC and the minimum fungicidal concentration (MFC).Results. The AgNP NAR showed a colloidal appearance with an average size of 14.71 nm and zeta potential measured at -33.3 mV, indicating a highly stable suspension. XRD analysis confirmed the crystal structure. FTIR spectra showed the presence of several functional groups of plant compounds, which play an important role in the coating and bioreduction processes. The antifungal activity against C. albicans showed an MIC of 3.55 µg ml-1 and an MFC of 7.1 µg ml-1. According to the growth kinetic assay in 12 h, there was a reduction of ~50% (<3 log10). Furthermore, AgNP NAR did not show mutagenic potential.Conclusion. The AgNP NAR obtained presented ideal characteristics for biomedical applications, good stability and promising antimicrobial activity.

Genomic reconstruction of an azole-resistant Candida parapsilosis outbreak and the creation of a multi-locus sequence typing scheme: a retrospective observational and genomic epidemiology study

BACKGROUND

Fluconazole-resistant Candida parapsilosis has emerged as a significant health-care-associated pathogen with a propensity to spread patient to patient and cause nosocomial outbreaks, similar to Candida auris. This study investigates a long-lasting outbreak of fluconazole-resistant C parapsilosis that was initially detected in December, 2018, and January, 2019, and officially declared in November, 2019; lasted multiple years; and involved several health-care centres in Berlin, Germany.

METHODS

In this retrospective, observational, and genomic epidemiology study, we used whole-genome sequencing (WGS) of isolates sent by German health-care facilities and laboratories to the National Reference Center for Invasive Fungal Infections (Jena, Germany) for antifungal susceptibility testing between Jan 1, 2016, and Dec 31, 2022. We included all potential outbreak samples (ie, isolates originating from Berlin that were resistant to fluconazole and voriconazole but susceptible to posaconazole) and all non-outbreak isolates that originated from outside of Berlin and were resistant to at least one azole. We also included a number of non-outbreak isolates from outside Berlin that were susceptible or resistant to azoles so that the total study dataset included a matching amount of outbreak and non-outbreak samples from Germany. We used admission and discharge records for patients involved in the outbreak and constructed a network of patient transfers in time and space. We used WGS data for included samples, complemented with WGS data for global samples obtained from the National Center for Biotechnology Information Sequence Read Archive, to construct single-nucleotide variant (SNV)-based phylogeny and perform SNV distance-based analyses. Additionally, we used the whole genomic dataset to identify loci with high discriminatory power to establish a multi-locus sequence typing (MLST) strategy for C parapsilosis.

FINDINGS

We identified 38 clonal, azole-resistant isolates of C parapsilosis causing 33 cases of invasive infection during a 2018-22 outbreak in multiple hospitals in Berlin. We also sequenced the genomes of 37 non-outbreak isolates. WGS revealed that outbreak strains were separated by a mean of 36 SNVs (SD 20), whereas outbreak strains differed from outgroup samples from Berlin and other regions of Germany by a mean of 2112 SNVs (828). Temporal and genomic reconstruction of the outbreak cases indicated that transfer of patients between health-care facilities was probably responsible for the persistent reimportation of the drug-resistant clone and subsequent person-to-person transmission. German outbreak strains were closely related to strains responsible for an outbreak in Canada and to isolates from Kuwait, Türkiye, and South Korea. Including the outbreak clone, we identified three distinct azole-resistant lineages carrying ERG11 Y132F in Germany. We identified four 750 bp loci in CPAR2_101400, CPAR2_101470, CPAR2_108720, and CPAR2_808110 for inclusion in our MLST strategy. Application of the MLST method to a global collection of 386 isolates identified 62 sequence types, with the outbreak strains all belonging to the same sequence type.

INTERPRETATION

This study underscores the emergence of drug-resistant C parapsilosis that can spread patient to patient within a health-care system, but also, possibly, internationally. Our findings highlight the importance of monitoring C parapsilosis epidemiology globally and of continuous surveillance and rigorous infection control measures at the local scale. We also developed a novel MLST scheme for genetic epidemiology and outbreak investigations, which could represent a faster and less expensive alternative to WGS.

FUNDING

German Federal Ministry for Education and Research, German Research Foundation, and German Ministry of Health.

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

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

Surveillance of pathogenic yeasts in hospital environments in Taiwan in 2020

BACKGROUND

A predominate azole-resistant Candida tropicalis clade 4 genotype causing candidemia has been detected in not only Taiwan but also China, Singapore, and Australia. It can also be detected on fruit surfaces. In addition to determining distribution and drug susceptibilities of pathogenic yeasts in environments of intensive care units of 25 hospitals in Taiwan, we would also like to investigate whether the azole-resistant C. tropicalis exists in Taiwan's hospital environment.

METHODS

The swabs of hospital environments were collected from August to November in 2020 and were cultured for yeasts. The yeasts were identified by rDNA sequence and the antifungal susceptibilities of those isolates were determined by the broth microdilution method.

RESULTS

The average yeast-culture rate of hospitals was 9.4% (217/2299). Sinks had the highest yeast-positive culture rate (32.7%), followed by bedside tables (28.9%), floors (26.0%), water-dispenser buttons (23.8%), and TV controller/touch panels (19.0%). Of 262 identified isolates, Candida parapsilosis was the most common species, accounting for 22.1%, followed by Filobasidium uniguttulatum (18.3%), Candida albicans (9.5%), C. tropicalis (8.0%), Candida glabrata (Nakaseomyces glabratus) (6.9%), and 30 other species (35.1%). Of the 21 C. tropicalis isolates from 11 units in 9 hospitals, 15 diploid sequence types (DSTs) were identified. The two DST506 fluconazole-resistant ones belonged to clade 4.

CONCLUSION

We detected not only various pathogenic yeast species but also the predominant clade 4 genotype of azole-resistant C. tropicalis. Our findings highlight and re-emphasize the importance of regular cleaning and disinfection practices.

Synergistic antifungal effect of thiophene derivative as an inhibitor of fluconazole-resistant Candida spp. biofilms

Candida species resistant to fluconazole have raised concern in the scientific medical community due to high mortality in patients with invasive disease. In developing countries, such as Brazil, fluconazole is the most commonly used antifungal, and alternative treatments are expensive or not readily available. Furthermore, the occurrence of biofilms is common, coupled with their inherent resistance to antifungal therapies and the host's immune system, these microbial communities have contributed to making infections caused by these yeasts an enormous clinical challenge. Therefore, there is an urgent need to develop alternative medicines, which surpass the effectiveness of already used therapies, but which are also effective against biofilms. Therefore, the present study aimed to describe for the first time the antifungal and antibiofilm action of the derivative 2-amino-5,6,7,8-tetrahydro-4 H-cyclohepta[b]thiophene-3-isopropyl carboxylate (2AT) against clinical strains of Candida spp. resistant to fluconazole (FLZ). When determining the minimum inhibitory concentrations (MIC), it was found that the compound has antifungal action at concentrations of 100 to 200 µg/mL, resulting in 100% inhibition of yeast cells. Its synergistic effect with the drug FLZ was also observed. The antibiofilm action of the compound in subinhibitory concentrations was detected, alone and in association with FLZ. Moreover, using scanning electron microscopy, it was observed that the compound 2AT in isolation was capable of causing significant ultrastructural changes in Candida. Additionally, it was also demonstrated that the compound 2AT acts by inducing characteristics compatible with apoptosis in these yeasts, such as chromatin condensation, when visualized by transmission electron microscopy, indicating the possible mechanism of action of this molecule. Furthermore, the compound did not exhibit toxicity in J774 macrophage cells up to a concentration of 4000 µg/mL. In this study, we identify the 2AT derivative as a future alternative for invasive candidiasis therapy, in addition, we highlighted the promise of a strategy combined with fluconazole in combating Candida infections, especially in cases of resistant isolates.

Evaluating the Antifungal Potential of Cinnamaldehyde: A Study of its Efficacy against Candida Species

Candida species exist as commensals in nature, colonizing the mucous membranes, gastrointestinal tract, vagina as well as the skin and usually cause infections in immunocompromised patients. C. albicans are known to be the most prevalent Candida species associated with infections, while there has been a significant surge in the incidence of Non-Candida albicans Candida species (NCAC) recently. The recent occurrences of the antifungal resistance in Candida, especially in NCAC species are quite alarming which raises the need for a safe and efficient alternative antimycotic drug. This study analyses the efficacy of cinnamaldehyde against Candida species, which is known to cause the majority of the fungal infections in humans. Cinnamaldehyde is a natural antimicrobial compound derived from cinnamon and has demonstrated significant antimycotic properties. Antifungal susceptibility profiles of cinnamaldehyde against Candida species were studied by disc diffusion as well as by broth microdilution assays. The mean diameter of the inhibition zone (IZ) formed by direct contact and disc volatilization assays were 61.26 mM and 65.20 mM, respectively. Both the minimum inhibitory concentration (MIC) and the minimum fungicidal concentration (MFC) of cinnamaldehyde ranged from 16-256 mg/L with mean MIC of 60.61 mg/L and a mean MFC of 81.94 mg/L. Co-incubation of Candida cells with cinnamaldehyde resulted in the loss of viable cells within 4 hours of incubation. Cinnamaldehyde was found to exhibit both fungistatic and fungicidal properties, making it a potent natural alternative for conventional antifungal agents.

Evaluation of outbreak persistence caused by multidrug-resistant and echinocandin-resistant Candida parapsilosis using multidimensional experimental and epidemiological approaches

Candida parapsilosis is known to cause severe and persistent outbreaks in clinical settings. Patients infected with multidrug-resistant C. parapsilosis (MDR Cp) isolates were identified in a large Turkish hospital from 2017-2020. We subsequently identified three additional patients infected with MDR Cp isolates in 2022 from the same hospital and two echinocandin-resistant (ECR) isolates from a single patient in another hospital. The increasing number of MDR and ECR isolates contradicts the general principle that the severe fitness cost associated with these phenotypes could prevent their dominance in clinical settings. Here, we employed a multidimensional approach to systematically assess the fitness costs of MDR and ECR C. parapsilosis isolates. Whole-genome sequencing revealed a novel MDR genotype infecting two patients in 2022. Despite severe in vitro defects, the levels and tolerances of the biofilms of our ECR and MDR isolates were generally comparable to those of susceptible wild-type isolates. Surprisingly, the MDR and ECR isolates showed major alterations in their cell wall components, and some of the MDR isolates consistently displayed increased tolerance to the fungicidal activities of primary human neutrophils and were more immunoevasive during exposure to primary human macrophages. Our systemic infection mouse model showed that MDR and ECR C. parapsilosis isolates had comparable fungal burden in most organs relative to susceptible isolates. Overall, we observed a notable increase in the genotypic diversity and frequency of MDR isolates and identified MDR and ECR isolates potentially capable of causing persistent outbreaks in the future.

New and emerging roles for inhalational and direct antifungal drug delivery approaches for treatment of invasive fungal infections

INTRODUCTION

The rising prevalence of difficult-to-treat, deep-seated invasive fungal diseases (IFD) has led to high mortality. Currently available antifungal treatments, administered predominantly orally or intravenously, may not sufficiently penetrate certain body sites, and/or are associated with systemic toxicity. Little is known about how to position alternative administration approaches such as inhalational and direct drug delivery routes.

AREAS COVERED

This review provides an updated overview of unconventional drug delivery strategies for managing IFD, focusing on inhalational (to target the lungs) and direct delivery methods to the central nervous system, bone/joint, and eyes. Novel compounds (e.g. opelconazole) and existing antifungals with innovative drug delivery systems currently undergoing clinical trials and/or used off-label in the clinical setting are discussed.

EXPERT OPINION

For both inhalational agents and direct delivery approaches, there are similar challenges that include the absence of: approved formulations for specific administration routes, delivery vehicles that are simple and safe to use whilst maintaining potency and efficiency of delivery, animal models suitable for investigating pharmacokinetic/pharmacodynamic profiles of inhaled antifungals, and consensus on the composite endpoints and intervals for of follow-up in clinical trials. To meet these challenges, cooperation of all stakeholders in drug development and regulation is required.

Antifungal susceptibility testing: applicability of methods and strategies for improving access in resource-constrained settings

Patients infected with antifungal-resistant fungi often do not respond to therapy, substantially increasing mortality risk. Some fungi are inherently resistant to particular antifungals, underscoring the importance of rapid genus identification or, ideally, rapid species identification. The past decade has seen an increase in variable antifungal resistance rates among human fungal pathogens, necessitating individual isolate testing. Various antifungal susceptibility testing (AFST) methods are most suitable for resource-constrained settings, including agar diffusion, gradient diffusion, broth microdilution, and automated tests, which all differ in speed, reliability, and cost; yet AFST remains largely unavailable in resource-constrained settings. This Personal View explores the feasibility of AFST implementation in resource-constrained settings and addresses broader accessibility concerns. We outline seven steps for implementation of AFST with an initial focus on accurate species identification (to predict intrinsic resistance) of Candida albicans, Candida parapsilosis, Candida glabrata, and Aspergillus fumigatus. New funding, laboratory and clinical training, clear protocols, access to media and reagents, acquisition and maintenance of quality control strains, and regular participation in an external quality assurance programme are all essential for sustainable AFST services. AFST is fundamental for patient care guidance, surveillance data generation, and strengthening antifungal stewardship programmes. Political commitment and international collaborations are crucial for enhanced AFST service delivery.

High-Resolution Melting Assay to Detect the Mutations That Cause the Y132F and G458S Substitutions at the ERG11 Gene Involved in Azole Resistance in Candida parapsilosis

BACKGROUND

Candida parapsilosis is a pathogenic yeast that has reduced susceptibility to echinocandins and ranks as the second or third leading cause of candidaemia, depending on the geographical region. This yeast often causes nosocomial infections, which are frequently detected as outbreaks. In recent years, resistance to azoles in C. parapsilosis has increased globally, primarily due to the accumulation of mutations in the ERG11 gene.

OBJECTIVES

In this study, we have developed an assay based on real-time PCR and high-resolution melting (HRM) curve analysis to detect two of the most prevalent mutations at ERG11 that confer resistance to fluconazole (Y132F and G458S).

METHODS

We designed allele-specific oligonucleotides that selectively bind to either the wild type or mutated sequences and optimised the conditions to ensure amplification of the specific allele, followed by detection via high-resolution melting (HRM) analysis.

RESULTS

The designed oligonucleotides to detect the Erg11Y132F and Erg11G458S mutations produced specific amplification of either WT or mutated alleles. We conducted a duplex real-time PCR combining oligonucleotides for the wild-type sequences in one mix, and oligonucleotides for the mutated alleles in another. Following this, we performed an analysis of the HRM curve to identify the amplified allele in each case. This technique was blindly evaluated on a set of 114 C. parapsilosis isolates, all of which were unequivocally identified using our approach.

CONCLUSION

This technique offers a new method for the early detection of azole resistance mechanism in C. parapsilosis.

Antifungal heteroresistance causes prophylaxis failure and facilitates breakthrough Candida parapsilosis infections

Breakthrough fungal infections in patients on antimicrobial prophylaxis during allogeneic hematopoietic cell transplantation (allo-HCT) represent a major and often unexplained cause of morbidity and mortality. Candida parapsilosis is a common cause of invasive candidiasis and has been classified as a high-priority fungal pathogen by the World Health Organization. In high-risk allo-HCT recipients on micafungin prophylaxis, we show that heteroresistance (the presence of a phenotypically unstable, low-frequency subpopulation of resistant cells (~1 in 10,000)) underlies breakthrough bloodstream infections by C. parapsilosis. By analyzing 219 clinical isolates from North America, Europe and Asia, we demonstrate widespread micafungin heteroresistance in C. parapsilosis. Standard antimicrobial susceptibility tests, such as broth microdilution or gradient diffusion assays, which guide drug selection for invasive infections, fail to detect micafungin heteroresistance in C. parapsilosis. To facilitate rapid detection of micafungin heteroresistance in C. parapsilosis, we constructed a predictive machine learning framework that classifies isolates as heteroresistant or susceptible using a maximum of ten genomic features. These results connect heteroresistance to unexplained antifungal prophylaxis failure in allo-HCT recipients and demonstrate a proof-of-principle diagnostic approach with the potential to guide clinical decisions and improve patient care.

Diagnosing fungal infections in clinical practice: a narrative review

BACKGROUND

Invasive fungal infections (IFI) present a major medical challenge, with an estimated 6.5 million cases annually, resulting in 3.8 million deaths. Pathogens such as Aspergillus spp. Candida spp. Mucorales spp. Cryptococcus spp. and other fungi species contribute to these infections, posing risks to immunocompromised individuals. Early and accurate diagnosis is crucial for effective treatment and better patient outcomes.

AREAS COVERED

This narrative review provides an overview of the current methods and challenges associated with diagnosing fungal diseases, including invasive aspergillosis and invasive candidiasis, as well as rare and endemic fungal infections. Various diagnostic techniques, including microscopy, culture, molecular diagnostics, and serological tests, are reviewed, highlighting their respective advantages and limitations and role in clinical guidelines. To illustrate, the need for improved diagnostic strategies to overcome existing challenges, such as the low sensitivity and specificity of current tests and the time-consuming nature of traditional culture-based methods, is addressed.

EXPERT OPINION

Current advancements in fungal infection diagnostics have significant implications for healthcare outcomes. Improved strategies like molecular testing and antigen detection promise early detection of fungal pathogens, enhancing patient management. Challenges include global access to advanced technologies and the need for standardized, user-friendly point-of-care diagnostics to improve diagnosis of fungal infections globally.

Rezafungin versus caspofungin for patients with candidaemia or invasive candidiasis in the intensive care unit: pooled analyses of the ReSTORE and STRIVE randomised trials

BACKGROUND

Rezafungin is an echinocandin approved in the US and EU to treat candidaemia and/or invasive candidiasis. This post-hoc, pooled analysis of the Phase 2 STRIVE and Phase 3 ReSTORE trials assessed rezafungin versus caspofungin in patients with candidaemia and/or invasive candidiasis (IC) in the intensive care unit (ICU) at randomisation.

METHODS

STRIVE and ReSTORE were randomised double-blind trials in adults with systemic signs and mycological confirmation of candidaemia and/or IC in blood or a normally sterile site ≤ 96 h before randomisation. Data were pooled for patients in the ICU at randomisation who received intravenous rezafungin (400 mg loading dose then 200 mg once weekly) or caspofungin (70 mg loading dose then 50 mg once daily) for ≤ 4 weeks. Outcomes were Day 30 all-cause mortality (primary outcome), Day 5 and 14 mycological eradication, time to negative blood culture, mortality attributable to candidaemia/invasive candidiasis, safety, and pharmacokinetics.

RESULTS

Of 294 patients in STRIVE/ReSTORE, 113 were in the ICU at randomisation (rezafungin n = 46; caspofungin n = 67). At baseline, ~ 30% of patients in each group had impaired renal function and/or an Acute Physiologic Assessment and Chronic Health Evaluation II score ≥ 20. One patient (in the caspofungin group) was neutropenic at baseline. Day 30 all-cause mortality was 34.8% for rezafungin versus 25.4% for caspofungin. Day 5 and 14 mycological eradication was 78.3% and 71.7% for rezafungin versus 59.7% and 65.7% for caspofungin, respectively. Median time to negative blood culture was 18 (interquartile range, 12.6-43.0) versus 38 (interquartile range, 15.9-211.3) h for rezafungin versus caspofungin (stratified log-rank P = 0.001; nominal, not adjusted for multiplicity). Candidaemia/IC-attributable deaths occurred in two rezafungin patients versus one caspofungin patient. Safety profiles were similar between groups. Overall, 17.4% (rezafungin) versus 29.9% (caspofungin) of patients discontinued due to treatment-emergent adverse events. Rezafungin exposure following the initial 400-mg dose was comparable between patients in the ICU at randomisation (n = 50) and non-ICU patients (n = 117).

CONCLUSIONS

Rezafungin was well tolerated and efficacious in critically ill, mainly non-neutropenic patients with candidaemia and/or IC. This analysis provides additional insights into the efficacy and safety of rezafungin in the ICU population.

Diversity and Antifungal Susceptibilities of Yeasts from Mangroves in Hong Kong, China-A One Health Aspect

While mangrove ecosystems are rich in biodiversity, they are increasingly impacted by climate change and urban pollutants. The current study provides first insights into the emergence of potentially pathogenic yeasts in Hong Kong's mangroves. Sediment and water samples were collected from ten urban and rural mangroves sites. Initial CHROMagarTM Candida Plus screening, representing the first application of this differential medium for water and soil samples collected from a non-clinical environment, enabled the rapid, preliminary phenotypic identification of yeast isolates from mangroves. Subsequent molecular profiling (ITS and/or 28S nrDNA sequencing) and antifungal drug susceptibility tests were conducted to further elucidate yeast diversity and drug resistance. A diversity of yeasts, including 45 isolates of 18 distinct species across 13 genera/clades, was isolated from sediments and waters from Hong Kong mangroves. Molecular profiling revealed a dominance of the Candida/Lodderomyces clade (44.4%), a group of notorious opportunistic pathogens. The findings also reveal a rich biodiversity of non-Candida/Lodderomyces yeasts in mangroves, including the first reported presence of Apiotrichum domesticum and Crinitomyces flavificans. A potentially novel Yamadazyma species was also discovered. Remarkably, 14.3% of the ubiquitous Candida parapsilosis isolates displayed resistance to multiple antifungal drugs, suggesting that mangroves may be reservoirs of multi-drug resistance. Wildlife, especially migratory birds, may disseminate these hidden threats. With significant knowledge gaps regarding the environmental origins, drug resistance, and public health impacts of pathogenic yeasts, urgent surveillance is needed from a One Health perspective. This study provides an early warning that unrestrained urbanization can unleash resistant pathogens from coastal ecosystems globally. It underscores the necessity for enhanced surveillance studies and interdisciplinary collaboration between clinicians, ornithologists, and environmental microbiologists to effectively monitor and manage this environmental health risk, ensuring the maintenance of 'One Health'.

Invasive candidiasis in a pediatric tertiary hospital: Epidemiology, antifungal susceptibility, and mortality rates

Invasive infections caused by non-albicans Candida are increasing worldwide. However, there is still a lack of information on invasive candidiasis (IC) in the pediatric setting, including susceptibility profiles and clonal studies. We investigated the clinical, epidemiologic, and laboratory characteristics of IC, possible changes in antifungal susceptibility profiles over time, and the occurrence of clonality in our tertiary children's hospital. We analyzed 123 non-duplicate Candida isolates from sterile sites of pediatric patients in a tertiary hospital in southern Brazil, between 2016 and 2021. Data on demographics, comorbidities, and clinical outcomes were collected. Candida species distribution, antifungal susceptibility profiles, biofilm production, and molecular epidemiology of isolates were assessed using reference methods. The range of IC incidence was 0.88-1.55 cases/1000 hospitalized patients/year, and the IC-related mortality rate was 20.3%. Of the total IC cases, 42.3% were in patients aged < 13 months. Mechanical ventilation, parenteral nutrition, and intensive care unit (ICU) admission were common in this group. In addition, ICU admission was identified as a risk factor for IC-related mortality. The main site of Candida spp. isolation was blood, and non-albicans Candida species were predominant (70.8%). No significant clonal spread was observed among isolates of the three most commonly isolated species, and 99.1% of all isolates were biofilm producers. Non-albicans Candida species were predominant in this study. Notably, clonal expansion and emergence of antifungal drug resistance were not observed in our pediatric setting.

Nosocomial transmission of fluconazole-resistant Candida glabrata bloodstream isolates revealed by whole-genome sequencing

The clonal transmission of fluconazole-resistant Candida glabrata isolates within hospitals has seldom been analyzed by whole-genome sequencing (WGS). We performed WGS on 79 C. glabrata isolates, comprising 31 isolates from three premature infants with persistent C. glabrata bloodstream infection despite antifungal treatment in the same neonatal intensive care unit (NICU) in 2022 and 48 (27 fluconazole-resistant and 21 fluconazole-susceptible dose-dependent) bloodstream isolates from 48 patients in 15 South Korean hospitals from 2010 to 2022. Phylogenetic analysis based on WGS single-nucleotide polymorphisms (SNPs) distinguished the 79 isolates according to multilocus sequence typing (MLST) (17 sequence type [ST]3, 13 ST7, two ST22, 41 ST26, four ST55, and two ST59 isolates) and unveiled two possible clusters of nosocomial transmission among ST26 isolates. One cluster from two premature infants with overlapping NICU hospitalizations in 2022 encompassed 15 fluconazole-resistant isolates harboring pleiotropic drug-resistance transcription factor (Pdr1p) P258L (13 isolates) or N1086I (two isolates), together with 10 fluconazole-susceptible dose-dependent isolates lacking Pdr1p SNPs. The other cluster indicated unforeseen clonal transmission of fluconazole-resistant bloodstream isolates among five patients (four post-lung transplantation and one with diffuse interstitial lung disease) in the same hospital over 8 months. Among these five isolates, four obtained after exposure to azole antifungals harbored distinct Pdr1p SNPs (N1091D, E388Q, K365E, and R376Q). The findings reveal the transmission patterns of clonal bloodstream isolates of C. glabrata among patients undergoing antifungal treatment, exhibiting different levels of fluconazole susceptibility or distinct Pdr1p SNP profiles.

IMPORTANCE

The prevalence of fluconazole-resistant bloodstream infections caused by Candida glabrata is increasing globally, but the transmission of these resistant strains within hospitals has rarely been documented. Through whole-genome sequencing and epidemiological analyses, this study identified two potential clusters of C. glabrata bloodstream infections within the same hospital, revealing the transmission of clonal C. glabrata strains with different levels of fluconazole susceptibility or distinct transcription factor pleiotropic drug resistance protein 1 (Pdr1p) single-nucleotide polymorphism profiles among patients receiving antifungal therapy.

Candidemia Following Severe COVID-19 in Hospitalised and Critical Ill Patients: A Systematic Review and Meta-Analysis

RATIONALE

The epidemiology and clinical impact of COVID-19-associated candidemia (CAC) remained uncertain, leaving gaps in understanding its prevalence, risk factors and outcomes.

METHODS

A systematic review and meta-analysis were conducted by searching PubMed, Embase and Scopus for reports of CAC prevalence, risk factors and clinical outcomes up to June 18, 2024. The generalised linear mixed model was employed to determine the prevalence and 95% confidence intervals (CIs). The risk factors and clinical outcomes were compared between patients with and without CAC using the inverse variance method.

RESULTS

From 81 studies encompassing 29 countries and involving 351,268 patients, the global prevalence of CAC was 4.33% (95% Cl, 3.16%-5.90%) in intensive care unit (ICU) patients. In ICUs, the pooled prevalence of CAC in high-income countries was significantly higher than that of lower-middle-income countries (5.99% [95% Cl, 4.24%-8.40%] vs. 2.23% [95% Cl, 1.06%-4.61%], p = 0.02). Resistant Candida species, including C. auris, C. glabrata (Nakaseomyces glabratus) and C. krusei (Pichia kudriavzveii), constituted 2% of ICU cases. The mortality rate for CAC was 68.40% (95% Cl, 61.86%-74.28%) among ICU patients. Several risk factors were associated with CAC, including antibiotic use, central venous catheter placement, dialysis, mechanical ventilation, tocilizumab, extracorporeal membrane oxygenation and total parenteral nutrition. Notably, the pooled odds ratio of tocilizumab was 2.59 (95% CI, 1.44-4.65).

CONCLUSIONS

The prevalence of CAC is substantial in the ICU setting, particularly in high-income countries. Several risk factors associated with CAC were identified, including several that are modifiable, offering the opportunity to mitigate the risk of CAC.

Antifungal pipeline: New tools for the treatment of mycoses

Fungal infections are becoming an escalating public health challenge, particularly among immunocompromised individuals. The partially limited efficacy of current antifungal treatments, their potential adverse effects, and the increasing problem of resistance emphasize the need for new treatment options. Existing antifungal classes-allylamines, azoles, echinocandins, polyenes, and pyrimidine analogs-face challenges due to their similarity with human cells and rising resistance. New antifungal agents, such as ibrexafungerp, rezafungin, oteseconazole, and miltefosine, offer novel mechanisms of action along with reduced toxicity. While antifungal resistance is a growing global concern, fungal infections in low- and middle-income countries (LMICs) present specific challenges with high rates of opportunistic infections like cryptococcosis and endemic mycoses such as histoplasmosis. The World Health Organization's fungal priority pathogens list highlights the prevalence of these infections in LMICs, where limited access to antifungal drugs and misuse are common. This review provides a comprehensive overview of these new agents and their mechanisms, and explores the challenges and roles of antifungal drugs in LMICs, where the burden of fungal infections is high. Continued research and development are essential to address the rising incidence and resistance of fungal infections globally.

Long-read sequencing and de novo genome assembly data of Candida parapsilosis HMC1 and Rhodotorula mucilaginosa LBMH1012, two novel isolates with antifungal resistance signatures

Candida parapsilosis and Rhodotorula mucilaginosa are opportunistic pathogens affecting mostly immunocompromised hosts. Both species have emerged as causes of invasive candidiasis and sepsis respectively. Here we present high-quality long-read genome assemblies for a strain of C. parapsilosis isolated from human breast milk, with multiple predicted signatures consistent with Candida Drug Resistance CDR1/CDR2 and Multi Drug Resistance MDR1-type genes, also for an environmental strain of R. mucilaginosa with multiresistance to azole antifungals. The genome sequencing was performed using the R9.4.1 flowcell with the MinION Mk1B sequencer (Oxford Nanopore Technologies, Oxford, UK). The draft genome of C. parapsilosis HMC1 was assembled from 85,745 long-reads and has 13,114,208 bp in length and comprises 10 contigs making it a highly contiguous assembly. The R. mucilaginosa LBMH1012 assembly has 23,636,156 bp in length and comprises 54 contigs. The genome completeness was estimated as 94.02 % and 91.40 % respectively using BUSCO. These data may be useful to explore the genetic diversity landscape in both species, infer potential causal genes for antifungal resistance and virulence, and represent an addition to the useful sequence space on emerging fungal pathogens.

Wild-type MIC distributions and epidemiological cutoff values for 5-flucytosine and Candida species as determined by EUCAST broth microdilution

Objectives

EUCAST has established clinical breakpoints and epidemiological cutoff values (ECOFFs) for Candida spp. However, limited data are available for 5-flucytosine (5-FC). We assessed the in vitro susceptibility of 5-FC against a large collection of clinical Candida species using EUCAST methodology and determined the associated ECOFFs.

Methods

A total of 5622 Candida isolates were collected from patients across the Netherlands between 2008 and 2024. 5-FC MICs were determined using the EUCAST microbroth dilution reference method. Furthermore, MICs were extracted from the EUCAST website. The MICs from this study and those extracted were used to determine ECOFFs and local ECOFFs (L-ECOFFs).

Results

5-FC exhibited potent in vitro activity against C. albicans, N. glabratus and C. parapsilosis, while decreased susceptibility was observed for C. tropicalis, Pichia species, K. marxianus, Y. lipolytica, and C. auris. The ECOFFs (mg/L) and the percentages of WT isolates for 5-FC were: C. albicans: 0.5 (97.2%), N. glabratus: 0.5 (96.6%), C. parapsilosis: 0.5 (99.5%) and P. kudriavzevii: 8 (99.4%). The L-ECOFF (mg/L) and the percentages of WT isolates for 5-FC were: C. dubliniensis: 0.25 (96.8%), C. tropicalis: 0.25 (67.2%), K. marxianus: 0.25 (48.0%), C. lusitaniae: 0.25 (86.5%), M. guillermondii: 0.125 (95.9%) and P. norvegiensis: 8 (94.2%).

Conclusions

5-FC remains a valuable drug to manage difficult-to-treat invasive Candida infections. In vitro susceptibility cannot be predicted based on species identification for most Candida species, but requires MIC-testing. ECOFFs will help to interpret the MICs to support treatment decisions.

Recent Challenges in Diagnosis and Treatment of Invasive Candidiasis in Neonates

Invasive Candida infections represent a significant cause of morbidity and mortality in the neonatal intensive care unit (NICU), particularly among preterm and low birth weight neonates. The nonspecific clinical presentation of invasive candidiasis, resembling that of bacterial sepsis with multiorgan involvement, makes the diagnosis challenging. Given the atypical clinical presentation and the potential detrimental effects of delayed treatment, empirical treatment is often initiated in cases with high clinical suspicion. This underscores the need to develop alternative laboratory methods other than cultures, which are known to have low sensitivity and a prolonged detection time, to optimize therapeutic strategies. Serum biomarkers, including mannan antigen/anti-mannan antibody and 1,3-β-D-glucan (BDG), both components of the yeast cell wall, a nano-diagnostic method utilizing T2 magnetic resonance, and Candida DNA detection by PCR-based techniques have been investigated as adjuncts to body fluid cultures and have shown promising results in improving diagnostic efficacy and shortening detection time in neonatal populations. This review aims to provide an overview of the diagnostic tools and the current management strategies for invasive candidiasis in neonates. Timely and accurate diagnosis followed by targeted antifungal treatment can significantly improve the survival and outcome of neonates affected by Candida species.

Tracking Candidemia Trends and Antifungal Resistance Patterns across Europe: An In-Depth Analysis of Surveillance Systems and Surveillance Studies

BACKGROUND

The WHO fungal priority list classifies Candida species as critical and high-priority pathogens, and the WHO GLASS fungi initiative seeks to establish a standardised global framework for antifungal resistance monitoring. We aimed to review resistance rates and antifungal resistance patterns across European surveillance systems and studies in response to these recent calls for action.

METHODS

A systematic review of national and international surveillance systems and peer-reviewed surveillance studies available up to June 2024 was conducted. Descriptive and trend analyses were performed on surveillance data reporting resistance to different antifungals in Candida spp.

RESULTS

In total, 6 national surveillance systems and 28 studies from 13 countries provided candidemia resistance data, mostly about the C. albicans, C. glabrata and C. parapsilosis complex. Azole resistance was most frequently reported (6/6 surveillance systems and 27/28 studies) with the highest resistance rate, especially for C. glabrata, in Croatia (100%, 28/28 isolates) and Slovenia (85.7%, 82/96) and C. parapsilosis in Croatia (80.6%, 54/67) and Italy (72.6%, 106/146). Echinocandin and polyene resistance rates were nearly zero. The number of isolates included in the surveillance systems increased over the years, particularly for C. albicans (+40-60 isolates/year), C. glabrata, and C. parapsilosis (+15-30 isolates/year). No surveillance system or study reported resistance data for C. auris. Pooled data from national surveillance revealed a decreasing trend in azole resistance in C. albicans and C. glabrata. The increasing azole-resistance trend in C. parapsilosis disappeared after adjusting for between-country heterogeneity. Overall, echinocandin and polyene resistance trends appeared relatively stable.

CONCLUSIONS

Awareness of antifungal resistance is growing, but further actions are needed to strengthen surveillance capacity and knowledge-sharing networks across Europe.

Clinical Characteristics of Candidemia Due to Candida parapsilosis with Serial Episodes: Insights from 5-Year Data Collection at a Tertiary Hospital in Korea

Candida parapsilosis is a common cause of non-albicans Candida species causing candidemia, particularly invasive candidiasis. This study aimed to characterize candidemia due to the C. parapsilosis complex with serial episodes, including clinical and mycological features.

METHODS

Blood isolates of the C. parapsilosis complex were collected from February 2019 to January 2023 at a tertiary Korean hospital. Species identification was performed using Vitek 2 or matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and antifungal susceptibility testing was performed using the Sensititre YeastOne® system. Clinical information was collected, and characteristics were analyzed according to single or serial isolates.

RESULTS

A total of 586 blood isolates of the C. parapsilosis complex were recovered from 68 candidemia patients during the study period. Of them, only the first isolate per patient was investigated. The only two isolates were resistant to fluconazole and no isolate was resistant to echinocandins, amphotericin B, or 5-FC. A single episode of candidemia occurred in 35 patients, while serial episodes occurred in 33 patients. Underlying liver diseases, use of vasopressors, ICU admission, severe sepsis, and CVC use were more frequent in patients with serial episodes. There was no significant difference in the median MIC values of antifungal agents or the use of azoles or amphotericin B between single and serial episodes. However, patients with serial episodes more frequently received echinocandin therapy. Overall, there was no significant difference in the 30-day mortality rate between patients with single and serial episodes.

CONCLUSION

Our data indicate that several factors related to the underlying conditions of the patients are associated with C. parapsilosis candidemia with serial episodes, rather than the characteristics of Candida itself.

Attributable mortality of candidemia - Results from the ECMM Candida III multinational European Observational Cohort Study

INTRODUCTION

Despite antifungal advancements, candidaemia still has a high mortality rate of up to 40%. The ECMM Candida III study in Europe investigated the changing epidemiology and outcomes of candidaemia for better understanding and management of these infections.

METHODS

In this observational cohort study, participating hospitals enrolled the first ten consecutive adults with blood culture-proven candidemia. Collected data included patient demographics, risk factors, hospital stay duration (follow-up of 90 days), diagnostic procedures, causative Candida spp., management details, and outcome. Controls were included in a 1:1 fashion from the same hospitals. The matching process ensured similarity in age (10-year range), primary underlying disease, hospitalization in intensive care versus non-ICU ward, and major surgery within 2 weeks before candidemia between cases and controls. Overall and attributable mortality were described, and a survival probability for cases and controls was performed.

RESULTS

One hundred seventy-one pairs consisting of patients with candidemia and matched controls from 28 institutions were included. In those with candidemia, overall mortality was 40.4%. Attributable mortality was 18.1% overall but differed between causative Candida species (7.7% for Candida albicans, 23.7% for Candida glabrata/Nakaseomyces glabratus, 7.7% for Candida parapsilosis and 63.6% for Candida tropicalis). Regarding risk factors, the presence of a central venous catheter, total parenteral nutrition and acute or chronic renal disease were significantly more common in cases versus controls. Duration of hospitalization, and especially that of ICU stay, was significantly longer in candidemia cases (20 (IQR 10-33) vs 15 days (IQR 7-28); p = 0.004).

CONCLUSIONS

Although overall and attributable mortality in this subgroup analysis of matched case/control pairs remains high, the attributable mortality appears to have decreased in comparison to historical cohorts. This decrease may be driven by improved prognosis of Candida albicans and Candida parapsilosis candidemia; whereas candidemia due to other Candida spp. exhibits a much higher attributable mortality.

Epidemiology of Invasive Candidiasis

Invasive candidiasis (IC) is an increasingly prevalent, costly, and potentially fatal infection brought on by the opportunistic yeast, Candida. Previously, IC has predominantly been caused by C. albicans which is often drug susceptible. There has been a global trend towards decreasing rates of infection secondary to C. albicans and a rise in non-albicans species with a corresponding increase in drug resistance creating treatment challenges. With advances in management of malignancies, there has also been an increase in the population at risk from IC along with a corresponding increase in incidence of breakthrough IC infections. Additionally, the emergence of C. auris creates many challenges in management and prevention due to drug resistance and the organism's ability to transmit rapidly in the healthcare setting. While the development of novel antifungals is encouraging for future management, understanding the changing epidemiology of IC is a vital step in future management and prevention.

Clinical characteristics and outcomes of patients with candidemia during the COVID-19 pandemic: Insights from experience in the Omicron era

BACKGROUND

In Taiwan, COVID-19 outbreaks caused by the Omicron variant occurred in 2022. We investigated the incidence of candidemia during COVID-19 pandemic and the mortality of candidemia patients with COVID-19 in Taiwan.

METHODS

The incidence of candidemia and fluconazole susceptibility of Candida species before (2015-2019) and during COVID-19 pandemic (2020-2023) at Kaohsiung Chang Gung Memorial Hospital were investigated. The associated factors with mortality in candidemia patients during COVID-19 pandemic were analyzed. Candidemia patients who had COVID-19 within the prior 90 days (case group, n = 34) were propensity-score matched for age, ICU admission, and abdominal surgery in a 1:4 ratio with candidemia patients without COVID-19 (control group, n = 136).

RESULTS

Age (adjusted odds ratio [AOR] = 1.02, 95% CI: 1.01-1.03), ICU stay (AOR = 1.84, 95% CI: 1.29-2.62), higher Charlson comorbidity index (AOR = 1.08, 95% CI: 1.03-1.13), corticosteroid use (AOR = 1.50, 95% CI: 1.04-2.17) were associated with increased risk of mortality; abdominal surgery (AOR = 0.47, 95% CI: 0.29-0.74) and infected by Candida parapsilosis (AOR = 0.61, 95% CI: 0.38-0.98) were associated with decreased risk of mortality. After matching, there was no significant difference in mortality rates between the case and control groups. The incidence of candidemia increased from 196 to 278 patients/100,000 admissions during COVID-19 pandemic, while the causative species of candidemia and fluconazole susceptibility rates were similar.

CONCLUSION

While the incidence of candidemia increased during COVID-19 pandemic, there was no significant difference in mortality between candidemia patients with and without COVID-19 in the Omicron era.

Short Tandem Repeat Genotyping of Medically Important Fungi: A Comprehensive Review of a Powerful Tool with Extensive Future Potential

Fungal infections pose an increasing threat to public health. New pathogens and changing epidemiology are a pronounced risk for nosocomial outbreaks. To investigate clonal transmission between patients and trace the source, genotyping is required. In the last decades, various typing assays have been developed and applied to different medically important fungal species. While these different typing methods will be briefly discussed, this review will focus on the development and application of short tandem repeat (STR) genotyping. This method relies on the amplification and comparison of highly variable STR markers between isolates. For most common fungal pathogens, STR schemes were developed and compared to other methods, like multilocus sequence typing (MLST), amplified fragment length polymorphism (AFLP) and whole genome sequencing (WGS) single nucleotide polymorphism (SNP) analysis. The pros and cons of STR typing as compared to the other methods are discussed, as well as the requirements for the development of a solid STR typing assay. The resolution of STR typing, in general, is higher than MLST and AFLP, with WGS SNP analysis being the gold standard when it comes to resolution. Although most modern laboratories are capable to perform STR typing, little progress has been made to standardize typing schemes. Allelic ladders, as developed for Aspergillus fumigatus, facilitate the comparison of STR results between laboratories and develop global typing databases. Overall, STR genotyping is an extremely powerful tool, often complimentary to whole genome sequencing. Crucial details for STR assay development, its applications and merit are discussed in this review.

Hybrids unleashed: exploring the emergence and genomic insights of pathogenic yeast hybrids

Hybridisation is the crossing of two divergent lineages that give rise to offspring carrying an admixture of both parental genomes. Genome sequencing has revealed that this process is common in the Saccharomycotina, where a growing number of hybrid strains or species, including many pathogenic ones, have been recently described. Hybrids can display unique traits that may drive adaptation to new niches, and some pathogenic hybrids have been shown to have higher prevalence over their parents in human and environmental niches, suggesting a higher fitness and potential to colonise humans. Here, we discuss how hybridisation and its genomic and phenotypic outcomes can shape the evolution of fungal species and may play a role in the emergence of new pathogens.

Breakthrough Invasive Fungal Infections in Patients With High-Risk Hematological Disorders Receiving Voriconazole and Posaconazole Prophylaxis: A Systematic Review

BACKGROUND

Primary antifungal prophylaxis with mold-active azoles is used to prevent invasive fungal infections in patients with high-risk hematological disorders; however, breakthrough infections occur, and the reasons for treatment failure are still not fully understood. To help inform clinical decisions, we sought to define microbiological, clinical, and pharmacological characteristics of proven and probable breakthrough invasive fungal infections (bIFIs) in patients with high-risk hematological disorders receiving voriconazole or posaconazole prophylaxis.

METHODS

We performed a systematic review of the literature following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The search strategy was last conducted on 19 April 2023.

RESULTS

We assessed 5293 studies for eligibility, and 300 were selected for data extraction. These studies described 1076 cases of bIFIs occurring under voriconazole (42.5%) or posaconazole (57.5%). The most commonly found pathogens were Aspergillus (40%), Mucorales (20%), Candida (18%), and Fusarium (9%) species. Mucorales were more frequent among voriconazole-emerging cases, whereas Aspergillus and Fusarium were more prevalent among posaconazole-emerging cases. Definitive, putative, or probable antifungal resistance was found in 31% of cases. Therapeutic drug monitoring showed subtherapeutic azole concentration in 32 of 90 (36%) cases. Infection-related mortality was reported in 117 cases and reached 35%.

CONCLUSIONS

In our systemic review, the most common bIFIs were aspergillosis, mucormycosis, candidiasis, and fusariosis. Antifungal resistance explains only a minority of cases. Subtherapeutic prophylaxis was frequent but rarely reported. Prospective studies are needed to better understand these infections and to establish optimal management.