Recent advances and future perspectives in the pharmacological treatment of Candida auris infections

Antifungal activity of synthetic xanthenone against fluconazole-resistant Candida auris and its mechanism of action

Candida auris, an emerging multidrug-resistant fungal pathogen discovered in Japan in 2009, poses a significant global health threat, with infections reported in about 25 countries. The escalation of drug-resistant strains underscores the urgent need for new treatment options. This study aimed to investigate the antifungal potential of 2,3,4,4a-tetrahydro-1H-xanthen-1-one (XA1) against C. auris, as well as its mechanism of action and toxic profile. The antifungal activity of XA1 was first evaluated by determining the minimum inhibitory concentration (MIC), time-kill kinetics and biofilm inhibition. In addition, structural changes, membrane permeability, reactive oxygen species (ROS) production, and in vitro and in vivo toxicity of C. auris after exposure to XA1 were investigated. The results indicated that XA1 exhibited an MIC of 50 μg/mL against C. auris, with time-kill kinetics highlighting its efficacy. Field emission scanning electron microscopy (FE-SEM) showed structural damage in XA1-treated cells, supported by increased membrane permeability leading to cell death. Furthermore, XA1 induced ROS production and significantly inhibited biofilm formation. Importantly, XA1 exhibited low cytotoxicity in human epidermal keratinocytes (HaCaT), with a cell viability of over 90% at 6.25 μg/mL. In addition, an LD50 of 17.68 μg/mL was determined in zebrafish embryos 24 hours post fertilization (hpf), with developmental delay observed at prolonged exposure at 6.25 μg/mL (48-96 hpf). These findings position XA1 as a promising candidate for further research and development of an effective antifungal agent.

Current Perspectives of Antifungal Therapy: A Special Focus on Candida auris

Candida auris is an emerging Candida sp. that has rapidly spread all over the world. The evidence regarding its origin and emerging resistance is still unclear. The severe infection caused by this species results in significant mortality and morbidity among the elderly and immunocompromised individuals. The development of drug resistance is the major factor associated with the therapeutic failure of existing antifungal agents. Previous studies have addressed the antifungal resistance profile and drug discovery for C. auris. However, complete coverage of this information in a single investigation is not yet available. In this review, we have mainly focused on recent developments in therapeutic strategies against C. auris. Based on the available information, several different approaches were discussed, including existing antifungal drugs, chemical compounds, essential oils, natural products, antifungal peptides, immunotherapy, antimicrobial photodynamic therapy, drug repurposing, and drug delivery systems. Among them, synthetic chemicals, natural products, and antifungal peptides are the prime contributors. However, a limited number of resources are available to prove the efficiency of these potential therapies in clinical usage. Therefore, we anticipate that the findings gathered in this review will encourage further in vivo studies and clinical trials.

The Cologne ECMM Excellence Center: A Two-Year Analysis of External Consultation Service for Invasive Fungal Infections

The European Confederation of Medical Mycology (ECMM), formed due to the surge in invasive fungal infections (IFI), initiated the Excellence Centers program in 2016 to guide stakeholders to leading medical mycology sites. This report focuses on the Cologne ECMM Excellence Center, recognized with Diamond status for active global involvement in 2017. The center offers free consultation via email and phone, responding within 24 h for life-threatening IFI, collecting data on origin, pathogens, infection details, and more. Over two years, 189 requests were received globally, predominantly from Germany (85%), mainly involving Aspergillus spp., Mucorales, and Candida spp. Fungal mixed infections occurred in 4% of cases. The center's service effectively addresses IFI challenges, advocating for a comprehensive study encompassing all ECMM Excellence Centers to enhance global mycological care. Proactive expansion of consultancy platforms is crucial, with future analyses needed to assess expert advice's impact on patient outcomes.

Predicting the next pandemic: VACCELERATE ranking of the WorldHealth Organization's Blueprint forAction toPreventEpidemics

INTRODUCTION

The World Health Organization (WHO)'s Research and Development (R&D) Blueprint for Action to Prevent Epidemics, a plan of action, highlighted several infectious diseases as crucial targets for prevention. These infections were selected based on a thorough assessment of factors such as transmissibility, infectivity, severity, and evolutionary potential. In line with this blueprint, the VACCELERATE Site Network approached infectious disease experts to rank the diseases listed in the WHO R&D Blueprint according to their perceived risk of triggering a pandemic. VACCELERATE is an EU-funded collaborative European network of clinical trial sites, established to respond to emerging pandemics and enhance vaccine development capabilities.

METHODS

Between February and June 2023, a survey was conducted using an online form to collect data from members of the VACCELERATE Site Network and infectious disease experts worldwide. Participants were asked to rank various pathogens based on their perceived risk of causing a pandemic, including those listed in the WHO R&D Blueprint and additional pathogens.

RESULTS

A total of 187 responses were obtained from infectious disease experts representing 57 countries, with Germany, Spain, and Italy providing the highest number of replies. Influenza viruses received the highest rankings among the pathogens, with 79 % of participants including them in their top rankings. Disease X, SARS-CoV-2, SARS-CoV, and Ebola virus were also ranked highly. Hantavirus, Lassa virus, Nipah virus, and henipavirus were among the bottom-ranked pathogens in terms of pandemic potential.

CONCLUSION

Influenza, SARS-CoV, SARS-CoV-2, and Ebola virus were found to be the most concerning pathogens with pandemic potential, characterised by transmissibility through respiratory droplets and a reported history of epidemic or pandemic outbreaks.

Phase 1b safety and pharmacokinetics of intravenous and oral fosmanogepix in patients with acute myeloid leukaemia and neutropenia

OBJECTIVES

Fosmanogepix (APX001), a first-in-class, intravenous (IV) and oral (PO) antifungal prodrug, is being developed to treat invasive fungal diseases (IFDs). Manogepix (APX001A; active moiety) targets fungal glycosylphosphatidylinositol-anchored cell wall transfer protein 1, inhibiting cell wall synthesis causing loss of viability. This open-label, multicentre, Phase 1b study in patients with AML and neutropenia (absolute neutrophil count <500 cells/μL; >10 days) undergoing chemotherapy aimed to assess tolerability, safety and pharmacokinetics (PK) of IV and PO fosmanogepix.

METHODS

Of 21 adult AML patients undergoing remission induction chemotherapy, 10 received IV fosmanogepix (600 mg; q24h) and 11 received oral fosmanogepix (500 mg; q24h) over 14 days, with a 28 day follow-up. Patients also received remission induction chemotherapy [sequential high-dose cytarabine and mitoxantrone (S-HAM) or 7 + 3 regimen] for AML and IFD prophylaxis (posaconazole). A two-compartmental PK model from previous studies in healthy volunteers was fitted to manogepix plasma data.

RESULTS

Of 26 fosmanogepix-related adverse events (AEs; IV: 14; PO: 12) in 9 (42.9%) patients [IV: 5 (50%); PO: 4 (36.4%)], none were serious or resulted in fosmanogepix discontinuation. Most frequently occurring fosmanogepix-related AEs were Grade 1/2 nausea [four events in three patients (14.3%)]; vomiting, ALT increase, and delirium [two events; two patients (9.5%) each]. One patient experienced fosmanogepix-related Grade 3 hypertension. Dose-corrected geometric mean ratio of AUC (PO-to-IV) was 95%. Elimination half-lives (∼2 days) were consistent with prior studies in healthy volunteers.

CONCLUSIONS

Fosmanogepix was safe and well tolerated in AML patients with neutropenia receiving remission induction chemotherapy. Safety and PK profiles were comparable to healthy volunteers.

Broad susceptibility of Candida auris strains to 8-hydroxyquinolines and mechanisms of resistance

The fungal pathogen Candida auris represents a severe threat to hospitalized patients. Its resistance to multiple classes of antifungal drugs and ability to spread and resist decontamination in healthcare settings make it especially dangerous. We screened 1,990 clinically approved and late-stage investigational compounds for the potential to be repurposed as antifungal drugs targeting C. auris and narrowed our focus to five Food and Drug Administration (FDA)-approved compounds with inhibitory concentrations under 10 µM for C. auris and significantly lower toxicity to three human cell lines. These compounds, some of which had been previously identified in independent screens, include three dihalogenated 8-hydroxyquinolines: broxyquinoline, chloroxine, and clioquinol. A subsequent structure-activity study of 32 quinoline derivatives found that 8-hydroxyquinolines, especially those dihalogenated at the C5 and C7 positions, were the most effective inhibitors of C. auris. To pursue these compounds further, we exposed C. auris to clioquinol in an extended experimental evolution study and found that C. auris developed only twofold to fivefold resistance to the compound. DNA sequencing of resistant strains and subsequent verification by directed mutation in naive strains revealed that resistance was due to mutations in the transcriptional regulator CAP1 (causing upregulation of the drug transporter MDR1) and in the drug transporter CDR1. These mutations had only modest effects on resistance to traditional antifungal agents, and the CDR1 mutation rendered C. auris more susceptible to posaconazole. This observation raises the possibility that a combination treatment involving an 8-hydroxyquinoline and posaconazole might prevent C. auris from developing resistance to this established antifungal agent. IMPORTANCE The rapidly emerging fungal pathogen Candida auris represents a growing threat to hospitalized patients, in part due to frequent resistance to multiple classes of antifungal drugs. We identify a class of compounds, the dihalogenated 8-hydroxyquinolines, with broad fungistatic ability against a diverse collection of 13 strains of C. auris. Although this compound has been identified in previous screens, we extended the analysis by showing that C. auris developed only modest twofold to fivefold increases in resistance to this class of compounds despite long-term exposure; a noticeable difference from the 30- to 500-fold increases in resistance reported for similar studies with commonly used antifungal drugs. We also identify the mutations underlying the resistance. These results suggest that the dihalogenated 8-hydroxyquinolines are working inside the fungal cell and should be developed further to combat C. auris and other fungal pathogens. Lohse and colleagues characterize a class of compounds that inhibit the fungal pathogen C. auris. Unlike many other antifungal drugs, C. auris does not readily develop resistance to this class of compounds.

Invasive Candida infection: epidemiology, clinical and therapeutic aspects of an evolving disease and the role of rezafungin

INTRODUCTION

Invasive Candida Infections (ICIs) have undergone a series of significant epidemiological, pathophysiological, and clinical changes during the last decades, with a shift toward non-albicans species, an increase in the rate of exogenous infections and clinical manifestations ranging from candidemia to an array of highly invasive and life-threatening clinical syndromes. The long-acting echinocandin rezafungin exhibits potent in-vitro activity against most wild-type and azole-resistant Candida spp. including C.auris.

AREAS COVERED

The following topics regarding candidemia only and ICIs were reviewed and addressed: i) pathogenesis; ii) epidemiology and temporal evolution of Candida species; iii) clinical approach; iv) potential role of the novel long-acting rezafungin in the treatment of ICIs.

EXPERT OPINION

Authors' expert opinion focused on considering the potential role of rezafungin in the evolving context of ICIs. Rezafungin, which combines a potent in-vitro activity against Candida species, including azole-resistant strains and C.auris, with a low likelihood of drug-drug interactions and a good safety profile, may revolutionize the treatment of candidemia/ICI. Indeed, it may shorten the length of hospital stays when clinical conditions allow and extend outpatient access to treatment of invasive candidiasis, especially when prolonged treatment duration is expected.

Increasing Number of Cases Due to Candida auris in North Italy, July 2019-December 2022

Candida auris is an emerging fungus that represents a serious health threat globally. In Italy, the first case was detected in July 2019. Then, one case was reported to the Ministry of Health (MoH) on January 2020. Nine months later, a huge number of cases were reported in northern Italy. Overall, 361 cases were detected in 17 healthcare facilities between July 2019 and December 2022 in the Liguria, Piedmont, Emilia-Romagna, and Veneto regions, including 146 (40.4%) deaths. The majority of cases (91.8%) were considered as colonised. Only one had a history of travel abroad. Microbiological data on seven isolates showed that all but one strain (85.7%) were resistant to fluconazole. All the environmental samples tested negative. Weekly screening of contacts was performed by the healthcare facilities. Infection prevention and control (IPC) measures were applied locally. The MoH nominated a National Reference Laboratory to characterise C. auris isolates and store the strains. In 2021, Italy posted two messages through the Epidemic Intelligence Information System (EPIS) to inform on the cases. On February 2022, a rapid risk assessment indicated a high risk for further spread within Italy, but a low risk of spread to other countries.

Broad sensitivity of Candida auris strains to quinolones and mechanisms of resistance

The fungal pathogen Candida auris represents a severe threat to hospitalized patients. Its resistance to multiple classes of antifungal drugs and ability to spread and resist decontamination in health-care settings make it especially dangerous. We screened 1,990 clinically approved and late-stage investigational compounds for the potential to be repurposed as antifungal drugs targeting C. auris and narrowed our focus to five FDA-approved compounds with inhibitory concentrations under 10 µM for C. auris and significantly lower toxicity to three human cell lines. These compounds, some of which had been previously identified in independent screens, include three dihalogenated 8-hydroxyquinolines: broxyquinoline, chloroxine, and clioquinol. A subsequent structure-activity study of 32 quinoline derivatives found that 8-hydroxyquinolines, especially those dihalogenated at the C5 and C7 positions, were the most effective inhibitors of C. auris . To pursue these compounds further, we exposed C. auris to clioquinol in an extended experimental evolution study and found that C. auris developed only 2- to 5-fold resistance to the compound. DNA sequencing of resistant strains and subsequent verification by directed mutation in naive strains revealed that resistance was due to mutations in the transcriptional regulator CAP1 (causing upregulation of the drug transporter MDR1 ) and in the drug transporter CDR1 . These mutations had only modest effects on resistance to traditional antifungal agents, and the CDR1 mutation rendered C. auris more sensitive to posaconazole. This observation raises the possibility that a combination treatment involving an 8-hydroxyquinoline and posaconazole might prevent C. auris from developing resistance to this established antifungal agent.

Abstract Importance

The rapidly emerging fungal pathogen Candida auris represents a growing threat to hospitalized patients, in part due to frequent resistance to multiple classes of antifungal drugs. We identify a class of compounds, the dihalogenated hydroxyquinolines, with broad fungistatic ability against a diverse collection of 13 strains of C. auris . Although this compound has been identified in previous screens, we extended the analysis by showing that C. auris developed only modest 2- to 5-fold increases in resistance to this class of compounds despite long-term exposure; a noticeable difference from the 30- to 500- fold increases in resistance reported for similar studies with commonly used antifungal drugs. We also identify the mutations underlying the resistance. These results suggest that the dihalogenated hydroxyquinolines are working inside the fungal cell and should be developed further to combat C. auris and other fungal pathogens.

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Lohse and colleagues characterize a class of compounds that inhibit the fungal pathogen C. auris . Unlike many other antifungal drugs, C. auris does not readily develop resistance to this class of compounds.

Prevalence of Fungal Drug Resistance in COVID-19 Infection: a Global Meta-analysis

Purpose

Secondary bacterial or fungal infections are one of the most important medical complications among patients with Coronavirus Disease 2019 (COVID-19). The emergence of multidrug-resistant (MDR) candida can cause many problems such as treatment failure, adverse clinical outcomes, and even disease outbreaks. This systematic review and meta-analysis aims to investigate the prevalence and outcomes of fungal drug-resistant in COVID-19 patients.

Methods

PubMed, Embase, Scopus, Cochrane Library, and Web of Science databases were searched for peer reviewed-articles published in English up to May 20, 2021. Heterogeneity across studies was evaluated using Cochrane’s Q test and the I² index. The pooled point prevalence and their corresponding 95% confidence intervals (CIs) were considered to estimate the prevalence of fungal drug resistance infection in COVID-19 patients.

Results

Eight eligible articles were included in our meta-analysis. The number of COVID-19 patients with fungal co-infection varied from 5 to 35 among selected studies. The overall pooled prevalence of fungal drug resistance among patients with co-infections of fungal and COVID-19 was 69% (95% CI: 37%, 94%) by using a random-effects model. In terms of specific species, the pooled meta-analysis for Candida Auris was estimated to be 100% (95%CI: 98%, 100%; I² = 0%), for Multi-Candida 59% (95%CI: 38%, 79%; I² = 12.5%), and for Aspergillus 15% (95%CI: 0%, 42%; I² = 0%).

Conclusion

Our study shows the high prevalence of fungal drug resistance in COVID-19 patients and emphasizes the need to strengthen antimicrobial stewardship programs, close monitoring for treatment failure, and the emergence of resistance upon treatment.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12281-022-00439-9.

Prospective Medicines against the Widespread, Emergent and Multidrug-Resistant Opportunistic Fungal Pathogen Candida auris: A Breath of Hope

The emergence of the pathogen Candida auris is a real concern worldwide, especially due to its multidrug resistance profile, besides the difficulties in establishing the correct identification by conventional laboratory methods and its capacity of causing outbreaks in healthcare settings. The limited arsenal of available antifungal drugs, coupled with the lack of momentum for the development of new reagents, represent a challenge in the management of such a pathogen. In this perspective, we have focused on discussing new, promising treatment options for C. auris infections. These novel drugs include an antifungal agent already approved for medical use in the United States of America, compounds that are already in clinical trials and those with potential for repurposing use against this important fungal pathogen.

Pharmacokinetics and Pharmacodynamics of Ibrexafungerp

On 2 June, 2021, the US Food and Drug Administration approved ibrexafungerp (formerly MK-3118 and SCY-078) for the treatment of vulvovaginal candidiasis, also known as vaginal yeast infection. Ibrexafungerp is the first drug approved in a novel antifungal class in more than two decades, and the Food and Drug Administration’s decision was based on positive results from two pivotal phase III studies in which oral ibrexafungerp proved both safe and effective in patients with vulvovaginal candidiasis. The decision was also based on substantial preclinical and clinical work in both the pharmacokinetics and pharmacodynamics of ibrexafungerp. This paper reviews that research and looks ahead to explore how this novel antifungal agent may be used in the future to address the expanding problem of drug-resistant mycotic infections.

Public health issues with Candida auris in COVID-19 patients

The ongoing pandemic of coronavirus disease 2019 (COVID‐19) has overwhelmed a number of medical facilities as well as a few entire health‐care systems. A novel issue co‐incident with the expeditious deployment of specialty care units for COVID‐19 inpatients is the worldwide epidemic of Candida auris infections. Since its first identification and classification in Japan in 2009, it has spread globally. This threat was predicted as C. auris has a high mortality rate, cryptic fomite spread, frequent misidentification since conventional methods do not detect it, and multidrug‐resistance. Since the April 2020 warning at the start of the COVID‐19 pandemic in the United States, C. auris has been delineated as an increasingly consequential source of significant nosocomial infections, emphasizing the added hazard of C. auris to COVID‐19 inpatients, particularly those in intensive care units.

Candida auris was a worldwide nosocomial epidemic prior to COVID‐19; it remains so!

This 21st century worldwide fungal epidemic complicates the COVID‐19 pandemic to jointly menace mankind

C. auris is multi‐drug resistant, requires expensive mass spectrometry equipment to diagnose, and has a high mortality rate in intensive care units

This nosocomial infection may persist on dry linen, sheets, floors, cell phones, and medical equipment for weeks

We propose a policy that documents the presence or absence of this invasive Candidal species in intensive care units during this COVID‐19 pandemic to aggressively eliminate it.