Estimation of Direct Healthcare Costs of Fungal Diseases in the United States

Suppression of hyphal formation and virulence of Candida albicans by natural and synthetic compounds

Candida albicans undergoes a morphological yeast-to-hyphal transition during infection, which plays a significant role in its pathogenesis. The filamentous morphology of the hyphal form has been identified as a virulence factor as it facilitates surface adherence, intertwining with biofilm, invasion, and damage to host tissues and organs. Hence, inhibition of filamentation in addition to biofilm formation is considered a viable strategy against C. albicans infections. Furthermore, a good understanding of the signaling pathways involved in response to environmental cues driving hyphal growth is also critical to an understanding of C. albicans pathogenicity and to develop novel therapies. In this review, first the clinical significance and transcriptional control of C. albicans hyphal morphogenesis are addressed. Then, various strategies employed to suppress filamentation, prevent biofilm formation, and reduce virulence are discussed. These strategies include the inhibition of C. albicans filament formation using natural or synthetic compounds, and their combination with other agents or nanoformulations.

Revising Conventional Wisdom About Histoplasmosis in the United States

Studies performed during the 1940s-1960s continue to serve as the foundation of the epidemiology of histoplasmosis given that many knowledge gaps persist regarding its geographic distribution, prevalence, and burden in the United States. We explore 3 long-standing, frequently cited, and somewhat incomplete epidemiologic beliefs about histoplasmosis: (1) histoplasmosis is the most common endemic mycosis in the United States, (2) histoplasmosis is endemic to the Ohio and Mississippi River Valleys, and (3) histoplasmosis is associated with bird or bat droppings. We also summarize recent insights about the clinical spectrum of histoplasmosis and changes in underlying conditions associated with the severe forms. Continuing to identify prevention opportunities will require better epidemiologic data, better diagnostic testing, and greater awareness about this neglected disease among health care providers, public health professionals, and the general public.

The landscape of candidemia during the COVID-19 pandemic

BACKGROUND

The COVID-19 pandemic has resulted in unprecedented healthcare challenges, and COVID-19 has been linked to secondary infections. Candidemia, a fungal healthcare-associated infection, has been described in patients hospitalized with severe COVID-19. However, studies of candidemia and COVID-19 co-infection have been limited in sample size and geographic scope. We assessed differences in patients with candidemia with and without a COVID-19 diagnosis.

METHODS

We conducted a case-level analysis using population-based candidemia surveillance data collected through the Centers for Disease Control and Prevention's Emerging Infections Program during April-August 2020 to compare characteristics of candidemia patients with and without a positive test for COVID-19 in the 30 days before their Candida culture using chi-square or Fisher exact tests.

RESULTS

Of the 251 candidemia patients included, 64 (25.5%) were positive for SARS-CoV-2. Liver disease, solid organ malignancies, and prior surgeries were each >3 times more common in patients without COVID-19 co-infection, whereas intensive care unit-level care, mechanical ventilation, having a central venous catheter, and receipt of corticosteroids and immunosuppressants were each >1.3 times more common in patients with COVID-19. All cause in-hospital fatality was two times higher among those with COVID-19 (62.5%) than without (32.1%).

CONCLUSIONS

One quarter of candidemia patients had COVID-19. These patients were less likely to have certain underlying conditions and recent surgery commonly associated with candidemia and more likely to have acute risk factors linked to COVID-19 care, including immunosuppressive medications. Given the high mortality, it is important for clinicians to remain vigilant and take proactive measures to prevent candidemia in patients with COVID-19.

Granulomatous Pneumocystis jiroveci Pneumonia in an HIV-Positive Patient on Antiretroviral Therapy: A Diagnostic Challenge

Human Immunodeficiency Virus (HIV)-related Opportunistic Infections (OI), including Pneumocystis jiroveci pneumonia (PCP), have become much less commonplace with anti-retroviral therapy (ART). Despite this, OIs are still common and it is important to remain vigilant for their presence and be aware of how ART and OI chemoprophylaxis may lead to atypical disease presentations. We present the case of a 51-year-old woman with HIV and CD4+ T helper lymphocytes cell count > 200 cells/ul on both ART and trimethoprim/sulfamethoxazole prophylaxis who presented with cavitating lung masses, mediastinal lymphadenopathy and pleural effusions. Negative bronchoalveolar lavage (BAL) and transbronchial biopsy (TBBx) prompted a second diagnostic procedure with a transthoracic core needle biopsy; the final diagnosis was granulomatous PCP. This case showcases a very rare presentation of PCP, with both large cavitating lung masses on imaging and granulomatous reaction on pathology, as well as the challenge of a potentially missed diagnosis with negative BAL and TBBx requiring transthoracic core needle biopsy for a final diagnosis.

Metamorphic Protein Folding Encodes Multiple Anti-Candida Mechanisms in XCL1

Candida species cause serious infections requiring prolonged and sometimes toxic therapy. Antimicrobial proteins, such as chemokines, hold great interest as potential additions to the small number of available antifungal drugs. Metamorphic proteins reversibly switch between multiple different folded structures. XCL1 is a metamorphic, antimicrobial chemokine that interconverts between the conserved chemokine fold (an α–β monomer) and an alternate fold (an all-β dimer). Previous work has shown that human XCL1 kills C. albicans but has not assessed whether one or both XCL1 folds perform this activity. Here, we use structurally locked engineered XCL1 variants and Candida killing assays, adenylate kinase release assays, and propidium iodide uptake assays to demonstrate that both XCL1 folds kill Candida, but they do so via different mechanisms. Our results suggest that the alternate fold kills via membrane disruption, consistent with previous work, and the chemokine fold does not. XCL1 fold-switching thus provides a mechanism to regulate the XCL1 mode of antifungal killing, which could protect surrounding tissue from damage associated with fungal membrane disruption and could allow XCL1 to overcome candidal resistance by switching folds. This work provides inspiration for the future design of switchable, multifunctional antifungal therapeutics.

Multidrug-resistant Trichosporon species: underestimated fungal pathogens posing imminent threats in clinical settings

Species of Trichosporon and related genera are widely used in biotechnology and, hence, many species have their genome sequenced. Importantly, yeasts of the genus Trichosporon have been increasingly identified as a cause of life-threatening invasive trichosporonosis (IT) in humans and are associated with an exceptionally high mortality rate. Trichosporon spp. are intrinsically resistant to frontline antifungal agents, which accounts for numerous reports of therapeutic failure when echinocandins are used to treat IT. Moreover, these fungi have low sensitivity to polyenes and azoles and, therefore, are potentially regarded as multidrug-resistant pathogens. However, despite the clinical importance of Trichosporon spp., our understanding of their antifungal resistance mechanisms is quite limited. Furthermore, antifungal susceptibility testing is not standardized, and there is a lack of interpretive epidemiological cut-off values for minimal inhibitory concentrations to distinguish non-wild type Trichosporon isolates. The route of infection remains obscure and detailed clinical and environmental studies are required to determine whether the Trichosporon infections are endogenous or exogenous in nature. Although our knowledge on effective IT treatments is rather limited and future randomized clinical trials are required to identify the best antifungal agent, the current paradigm advocates the use of voriconazole, removal of central venous catheters and recovery from neutropenia.

Molecular and genetic basis of azole antifungal resistance in the opportunistic pathogenic fungus Candida albicans

Candida albicans is an opportunistic yeast and the major human fungal pathogen in the USA, as well as in many other regions of the world. Infections with C. albicans can range from superficial mucosal and dermatological infections to life-threatening infections of the bloodstream and vital organs. The azole antifungals remain an important mainstay treatment of candidiasis and therefore the investigation and understanding of the evolution, frequency and mechanisms of azole resistance are vital to improving treatment strategies against this organism. Here the organism C. albicans and the genetic changes and molecular bases underlying the currently known resistance mechanisms to the azole antifungal class are reviewed, including up-regulated expression of efflux pumps, changes in the expression and amino acid composition of the azole target Erg11 and alterations to the organism's typical sterol biosynthesis pathways. Additionally, we update what is known about activating mutations in the zinc cluster transcription factor (ZCF) genes regulating many of these resistance mechanisms and review azole import as a potential contributor to azole resistance. Lastly, investigations of azole tolerance in C. albicans and its implicated clinical significance are reviewed.

Treatment Practices for Adults with Candidemia at Nine Active Surveillance Sites - United States, 2017-2018

BACKGROUND

Candidemia is a common opportunistic infection causing substantial morbidity and mortality. Because of an increasing proportion of non-albicans Candida species and rising antifungal drug resistance, the Infectious Diseases Society of America (IDSA) changed treatment guidelines in 2016 to recommend echinocandins over fluconazole as first-line treatment for adults with candidemia. We describe candidemia treatment practices and adherence to the updated guidelines.

METHODS

During 2017-2018, the Emerging Infections Program conducted active population-based candidemia surveillance at nine U.S. sites using a standardized case definition. We assessed factors associated with initial antifungal treatment for the first candidemia case among adults using multivariable logistic regression models. To identify instances of potentially inappropriate treatment, we compared the first antifungal drug received with species and antifungal susceptibility testing (AFST) results from initial blood cultures.

RESULTS

Among 1,835 patients who received antifungal treatment, 1,258 (68.6%) received an echinocandin and 543 (29.6%) received fluconazole as initial treatment. Cirrhosis (adjusted odds ratio = 2.06, 95% confidence interval: 1.29-3.29) was the only underlying medical condition significantly associated with initial receipt of an echinocandin (versus fluconazole). Over half (n = 304, 56.0%) of patients initially treated with fluconazole grew a non-albicans species. Among 265 patients initially treated with fluconazole and with fluconazole AFST results, 28 (10.6%) had a fluconazole-resistant isolate.

CONCLUSIONS

A substantial proportion of patients with candidemia were initially treated with fluconazole, resulting in potentially inappropriate treatment for those involving non-albicans or fluconazole-resistant species. Reasons for non-adherence to IDSA guidelines should be evaluated, and clinician education is needed.

Recent Trends in the Epidemiology of Fungal Infections

The breadth of fungi causing human disease and the spectrum of clinical presentations associated with these infections has widened. Epidemiologic trends display dramatic shifts with expanding geographic ranges, identification of new at-risk groups, increasing prevalence of resistant infections, and emergence of novel multidrug-resistant pathogenic fungi. Certain fungi have been transmitted between patients in clinical settings. Major health events not typically associated with mycoses resulted in larger proportions of the population susceptible to secondary fungal infections. Many health care-related, environmental, and socioeconomic factors have influenced these epidemiologic shifts. This review summarizes updates to clinically significant fungal pathogens in North America.

Impact of the SARS-CoV-2 Pandemic in Candidaemia, Invasive Aspergillosis and Antifungal Consumption in a Tertiary Hospital

In addition to the increase in fungal infections that has been observed in the last few decades, it has been reported that severe clinical COVID-19 can increase the risk of invasive fungal infections. The main objective of this study was to evaluate if there had been an increase in candidaemia and invasive pulmonary aspergillosis (IPA) cases since the onset of the SARS-CoV-2 pandemic. Data were retrospectively collected from April 2019 to March 2021, from patients admitted to Consorcio Hospital General Universitario de Valencia (Spain). A total of 152 candidaemia cases (56 of which were due to Candida auris) and 108 possible IPA cases were detected. A great increase in candidaemia cases was produced during the first and the third epidemic waves of the SARS-CoV-2 pandemic (June 2020, and January 2021, respectively), while an increase in IPA cases was produced during the third wave. The 28-day mortality rates in patients affected by candidaemia and IPA increased in 2020 and 2021. C. auris has displaced the other Candida species, becoming the most isolated Candida species in blood cultures since the onset of the SARS-CoV-2 pandemic. Antifungal consumption increased in 2020 when compared to 2019, especially echinocandins, voriconazole and isavuconazole.

Investigational Agents for the Treatment of Resistant Yeasts and Molds

Purpose of Review

This review summarizes the investigational antifungals in clinical development with the potential to address rising drug resistance patterns. The relevant pharmacodynamics, spectrum of activity, preclinical studies, and latest clinical trial data are described.

Recent Findings

Agricultural and medicinal antifungal use has been selected for inherently drug-resistant fungi and acquired resistance mechanisms. The rates of fungal infections and immunocompromised populations continue to grow as few new antifungals have hit the market. Several agents with the potential to address the emergence of multidrug-resistant (MDR) molds and yeasts are in clinical development.

Summary

Evolved formulations of echinocandins, polyenes, and triazoles offer less toxicity, convenient dosing, and greater potency, potentially expanding these classes’ indications. Ibrexafungerp, olorofim, oteseconazole, and fosmanogepix possess novel mechanisms of actions with potent activity against MDR fungi. Successful clinical development is neither easy nor guaranteed; thus, perpetual efforts to discover new antifungals are needed.

Molecular Epidemiology and Antifungal Susceptibility of Trichophyton Isolates in Greece: Emergence of Terbinafine-Resistant Trichophytonmentagrophytes Type VIII Locally and Globally

Trichophyton isolates with reduced susceptibility to antifungals are now increasingly reported worldwide. We therefore studied the molecular epidemiology and the in vitro antifungal susceptibility patterns of Greek Trichophyton isolates over the last 10 years with the newly released EUCAST reference method for dermatophytes. Literature was reviewed to assess the global burden of antifungal resistance in Trichophyton spp. The in vitro susceptibility of 112 Trichophyton spp. molecularly identified clinical isolates (70 T. rubrum, 24 T. mentagrophytes, 12 T. interdigitale and 6 T. tonsurans) was tested against terbinafine, itraconazole, voriconazole and amorolfine (EUCAST E.DEF 11.0). Isolates were genotyped based on the internal transcribed spacer (ITS) sequences and the target gene squalene epoxidase (SQLE) was sequenced for isolates with reduced susceptibility to terbinafine. All T. rubrum, T. interdigitale and T. tonsurans isolates were classified as wild-type (WT) to all antifungals, whereas 9/24 (37.5%) T. mentagrophytes strains displayed elevated terbinafine MICs (0.25–8 mg/L) but not to azoles and amorolfine. All T. interdigitale isolates belonged to ITS Type II, while T. mentagrophytes isolates belonged to ITS Type III* (n = 11), VIII (n = 9) and VII (n = 4). All non-WT T. mentagrophytes isolates belonged to Indian Genotype VIII and harbored Leu393Ser (n = 5) and Phe397Leu (n = 4) SQLE mutations. Terbinafine resistance rates ranged globally from 0–44% for T. rubrum and 0–76% for T. interdigitale/T. mentagrophytes with strong endemicity. High incidence (37.5%) of terbinafine non-WT T. mentagrophytes isolates (all belonging to ITS Type VIII) without cross-resistance to other antifungals was found for the first time in Greece. This finding must alarm for susceptibility testing of dermatophytes at a local scale particularly in non-responding dermatophytoses.

Synergism of Zinc Oxide Quantum Dots with Antifungal Drugs: Potential Approach for Combination Therapy against Drug Resistant Candida albicans

Candidiasis caused by Candida albicans is one of the most common microbial infections. Azoles, polyenes, allylamines, and echinocandins are classes of antifungals used for treating Candida infections. Standard drug doses often become ineffective due to the emergence of multidrug resistance (MDR). This leads to the use of higher drug doses for prolonged duration, resulting in severe toxicity (nephrotoxicity and liver damage) in humans. However, combination therapy using very low concentrations of two or more antifungal agents together, can lower such toxicity and limit evolution of drug resistance. Herein, 4–6 nm zinc oxide quantum dots (ZnO QDs) were synthesized and their in vitro antifungal activities were assessed against drug-susceptible (G1, F1, and GU4) and resistant (G5, F5, and GU5) isolates of C. albicans. In broth microdilution assay, ZnO QDs exhibited dose dependent growth inhibition between 0 – 200 µg/ml and almost 90% growth was inhibited in all Candida strains at 200 µg/ml of ZnO QDs. Synergy between ZnO QDs and antifungal drugs at sub-inhibitory concentrations of each was assessed by checkerboard analysis and expressed in terms of the fractional inhibitory concentration (FIC) index. ZnO QDs were used with two different classes of antifungals (azoles and polyenes) against Candida isolates: combination 1 (with fluconazole); combination 2 (with ketoconazole); combination 3 (with amphotericin B), and combination 4 (with nystatin). Results demonstrated that the potency of combinations of ZnO QDs with antifungal drugs even at very low concentrations of each was higher than their individual activities against the fungal isolates. The FIC index was found to be less than 0.5 for all combinations in the checkerboard assay, which confirmed synergism between sub-inhibitory concentrations of ZnO QDs (25 µg/ml) and individual antifungal drugs. Synergism was further confirmed by spot assay where cell viabilities of Candida strains were significantly reduced in all combinations, which was clearly evident from the disappearance of fungal cells on agar plates containing antifungal combinations. For safer clinical use, the in vitro cytotoxic activity of ZnO QDs was assessed against HeLa cell line and it was found that ZnO QDs were non-toxic at 25 µg/ml. Results suggested that the combination of ZnO QDs with drugs potentiate antimicrobial activity through multitargeted action. ZnO QDs could therefore offer a versatile alternative in combination therapy against MDR fungal pathogens, wherein lowering drug concentrations could reduce toxicity and their multitargeted action could limit evolution of fungal drug resistance.

Trends in Agricultural Triazole Fungicide Use in the United States, 1992-2016 and Possible Implications for Antifungal-Resistant Fungi in Human Disease

BACKGROUND

The fungus Aspergillus fumigatus (A. fumigatus) is the leading cause of invasive mold infections, which cause severe disease and death in immunocompromised people. Use of triazole antifungal medications in recent decades has improved patient survival; however, triazole-resistant infections have become common in parts of Europe and are emerging in the United States. Triazoles are also a class of fungicides used in plant agriculture, and certain triazole-resistant A. fumigatus strains found causing disease in humans have been linked to environmental fungicide use.

OBJECTIVES

We examined U.S. temporal and geographic trends in the use of triazole fungicides using U.S. Geological Survey agricultural pesticide use estimates.

DISCUSSION

Based on our analysis, overall tonnage of triazole fungicide use nationwide was relatively constant during 1992-2005 but increased >4-fold during 2006-2016 to 2.9 million kg in 2016. During 1992-2005, triazole fungicide use occurred mostly in orchards and grapes, wheat, and other crops, but recent increases in use have occurred primarily in wheat, corn, soybeans, and other crops, particularly in Midwest and Southeast states. We conclude that, given the chemical similarities between triazole fungicides and triazole antifungal drugs used in human medicine, increased monitoring for environmental and clinical triazole resistance in A. fumigatus would improve overall understanding of these interactions, as well as help identify strategies to mitigate development and spread of resistance. https://doi.org/10.1289/EHP7484.

Mortality Trends in Risk Conditions and Invasive Mycotic Disease in the United States, 1999-2018

BACKGROUND

Invasive fungal infections (IFIs) in the United States are chronically underdiagnosed and a lack of coordinated surveillance makes the true burden of disease difficult to determine. The purpose of this analysis was to capture mortality-associated burden of risk conditions and fungal infections.

METHODS

We analyzed data from the National Vital Statistics System from 1999-2018 to estimate the mortality attributed to risk conditions and related fungal disease.

RESULTS

The number of risk conditions associated with fungal disease is steadily rising in the United States with 1,047,422 diagnoses at time of death in 2018. While fungal disease decreased substantially from 1999 to 2010, primarily due to the control of HIV infection, the number deaths with fungal diagnosis has increased in the non-HIV cohort, with significant increases in patients with diabetes, cancer, immunosuppressive disorders, or sepsis.

CONCLUSION

The landscape of individuals at risk for serious fungal diseases is changing, with a continued decline in HIV-associated incidence, but increased diagnoses in patients with cancer, sepsis, immunosuppressive disorders, and influenza. Additionally, there is an overall increase in the number of fungal infections in recent years, indicating a failure to control fungal disease mortality in these new immunocompromised cohorts. Improvement in prevention and management of fungal diseases is needed to control morbidity and mortality in the rising number of immunocompromised and at-risk patients in the United States.

Cation Transporters of Candida albicans-New Targets to Fight Candidiasis?

Candidiasis is the wide-spread fungal infection caused by numerous strains of yeast, with the prevalence of Candida albicans. The current treatment of candidiasis is becoming rather ineffective and costly owing to the emergence of resistant strains; hence, the exploration of new possible drug targets is necessary. The most promising route is the development of novel antibiotics targeting this pathogen. In this review, we summarize such candidates found in C. albicans and those involved in the transport of (metal) cations, as the latter are essential for numerous processes within the cell; hence, disruption of their fluxes can be fatal for C. albicans.

Membrane-Interacting Antifungal Peptides

The incidence of invasive fungal infections is increasing worldwide, resulting in more than 1.6 million deaths every year. Due to growing antifungal drug resistance and the limited number of currently used antimycotics, there is a clear need for novel antifungal strategies. In this context, great potential is attributed to antimicrobial peptides (AMPs) that are part of the innate immune system of organisms. These peptides are known for their broad-spectrum activity that can be directed toward bacteria, fungi, viruses, and/or even cancer cells. Some AMPs act via rapid physical disruption of microbial cell membranes at high concentrations causing cell leakage and cell death. However, more complex mechanisms are also observed, such as interaction with specific lipids, production of reactive oxygen species, programmed cell death, and autophagy. This review summarizes the structure and mode of action of antifungal AMPs, thereby focusing on their interaction with fungal membranes.

The Heat Shock Transcription Factor HsfA Is Essential for Thermotolerance and Regulates Cell Wall Integrity in Aspergillus fumigatus

The deleterious effects of human-induced climate change have long been predicted. However, the imminent emergence and spread of new diseases, including fungal infections through the rise of thermotolerant strains, is still neglected, despite being a potential consequence of global warming. Thermotolerance is a remarkable virulence attribute of the mold Aspergillus fumigatus. Under high-temperature stress, opportunistic fungal pathogens deploy an adaptive mechanism known as heat shock (HS) response controlled by heat shock transcription factors (HSFs). In eukaryotes, HSFs regulate the expression of several heat shock proteins (HSPs), such as the chaperone Hsp90, which is part of the cellular program for heat adaptation and a direct target of HSFs. We recently observed that the perturbation in cell wall integrity (CWI) causes concomitant susceptibility to elevated temperatures in A. fumigatus, although the mechanisms underpinning the HS response and CWI cross talking are not elucidated. Here, we aim at further deciphering the interplay between HS and CWI. Our results show that cell wall ultrastructure is severely modified when A. fumigatus is exposed to HS. We identify the transcription factor HsfA as essential for A. fumigatus viability, thermotolerance, and CWI. Indeed, HS and cell wall stress trigger the coordinated expression of both hsfA and hsp90. Furthermore, the CWI signaling pathway components PkcA and MpkA were shown to be important for HsfA and Hsp90 expression in the A. fumigatus biofilms. Lastly, RNA-sequencing confirmed that hsfA regulates the expression of genes related to the HS response, cell wall biosynthesis and remodeling, and lipid homeostasis. Our studies collectively demonstrate the connection between the HS and the CWI pathway, with HsfA playing a crucial role in this cross-pathway regulation, reinforcing the importance of the cell wall in A. fumigatus thermophily.

Mechanisms of fungal dissemination

Fungal infections are an increasing threat to global public health. There are more than six million fungal species worldwide, but less than 1% are known to infect humans. Most of these fungal infections are superficial, affecting the hair, skin and nails, but some species are capable of causing life-threatening diseases. The most common of these include Cryptococcus neoformans, Aspergillus fumigatus and Candida albicans. These fungi are typically innocuous and even constitute a part of the human microbiome, but if these pathogens disseminate throughout the body, they can cause fatal infections which account for more than one million deaths worldwide each year. Thus, systemic dissemination of fungi is a critical step in the development of these deadly infections. In this review, we discuss our current understanding of how fungi disseminate from the initial infection sites to the bloodstream, how immune cells eliminate fungi from circulation and how fungi leave the blood and enter distant organs, highlighting some recent advances and offering some perspectives on future directions.

Core Recommendations for Antifungal Stewardship: A Statement of the Mycoses Study Group Education and Research Consortium

In recent years, the global public health community has increasingly recognized the importance of antimicrobial stewardship (AMS) in the fight to improve outcomes, decrease costs, and curb increases in antimicrobial resistance around the world. However, the subject of antifungal stewardship (AFS) has received less attention. While the principles of AMS guidelines likely apply to stewarding of antifungal agents, there are additional considerations unique to AFS and the complex field of fungal infections that require specific recommendations. In this article, we review the literature on AMS best practices and discuss AFS through the lens of the global core elements of AMS. We offer recommendations for best practices in AFS based on a synthesis of this evidence by an interdisciplinary expert panel of members of the Mycoses Study Group Education and Research Consortium. We also discuss research directions in this rapidly evolving field. AFS is an emerging and important component of AMS, yet requires special considerations in certain areas such as expertise, education, interventions to optimize utilization, therapeutic drug monitoring, and data analysis and reporting.

Vaccines for human fungal diseases: close but still a long way to go

Despite the substantial global burden of human fungal infections, there are no approved fungal vaccines to protect at risk individuals. Here, we review the progress that has been made and the challenges that lie ahead in the quest towards efficacious fungal vaccines. In mouse studies, protection has been achieved with vaccines directed against fungal pathogens, including species of Candida, Cryptococcus, and Aspergillus, that most commonly cause life-threatening human disease. Encouraging results have been obtained with vaccines composed of live-attenuated and killed fungi, crude extracts, recombinant subunit formulations, and nucleic acid vaccines. Novel adjuvants that instruct the immune system to mount the types of protective responses needed to fight mycotic infections are under development. Candidate vaccines include those that target common antigens expressed on multiple genera of fungi thereby protecting against a broad range of mycoses. Encouragingly, three vaccines have reached human clinical trials. Still, formidable obstacles must be overcome before we will have fungal vaccines licensed for human use.

Invasive Aspergillosis After Influenza and Other Viral Respiratory Infections Among Intensive Care Unit Patients in a Commercially Insured Population in the United States, 2013-2018

Influenza-associated aspergillosis (IAA) is an emerging phenomenon in intensive care unit patients with severe influenza. In a large US health insurance claims database, IAA was uncommon (0.3%) during 2013-2018. The low IAA frequency likely reflects underdiagnosis and differences in medical practices or epidemiologic differences.

Antifungal Liposomes Directed by Dectin-2 Offer a Promising Therapeutic Option for Pulmonary Aspergillosis

Invasive fungal diseases cause millions of deaths each year. There are currently approximately 300,000 acute cases of aspergillosis, most of which result from a pulmonary infection of immunocompromised patients by the common soil organism and opportunistic pathogen Aspergillus fumigatus. Patients are treated with antifungal drugs, such as amphotericin B (AmB). However, AmB has serious limitations due to human organ toxicity. AmB is slightly less toxic if loaded in liposomes, such as AmBisome or AmB-loaded liposomes (AmB-LLs). Even with antifungal therapy, recurrent infections are common, and 1-year fatality rates may exceed 50%. We have previously shown that coating AmB-LLs with the extracellular oligomannan-binding domain of the C-type lectin receptor Dectin-2 (DEC2-AmB-LLs) effectively targets DEC2-AmB-LLs to cell walls, exopolysaccharide matrices, and biofilms of fungal pathogens in vitro. In vitro, DEC2-AmB-LLs reduce the effective dose of AmB for 95% inhibition and killing of A. fumigatus 10-fold compared to that of untargeted AmB-LLs. Herein we tested the antifungal activity of DEC2-AmB-LLs relative to that of untargeted AmB-LLs in immunosuppressed mice with pulmonary aspergillosis. Remarkably, DEC2-AmB-LLs bound 30-fold more efficiently to A. fumigatus at sites of infection in the lungs. Furthermore, Dectin-2-targeted liposomes delivering AmB at a dose of 0.2 mg/kg of body weight significantly reduced the fungal burden in lungs compared to results with untargeted AmB-LLs at 0.2 mg/kg and micellar voriconazole at 20 mg/kg and prolonged mouse survival. By dramatically increasing the efficacy of antifungal drugs at low doses, targeted liposomes have the potential to create a new clinical paradigm to treat diverse fungal diseases.

Pneumocystis Pneumonia: Immunity, Vaccines, and Treatments

For individuals who are immunocompromised, the opportunistic fungal pathogen Pneumocystis jirovecii is capable of causing life-threatening pneumonia as the causative agent of Pneumocystis pneumonia (PCP). PCP remains an acquired immunodeficiency disease (AIDS)-defining illness in the era of antiretroviral therapy. In addition, a rise in non-human immunodeficiency virus (HIV)-associated PCP has been observed due to increased usage of immunosuppressive and immunomodulating therapies. With the persistence of HIV-related PCP cases and associated morbidity and mortality, as well as difficult to diagnose non-HIV-related PCP cases, an improvement over current treatment and prevention standards is warranted. Current therapeutic strategies have primarily focused on the administration of trimethoprim-sulfamethoxazole, which is effective at disease prevention. However, current treatments are inadequate for treatment of PCP and prevention of PCP-related death, as evidenced by consistently high mortality rates for those hospitalized with PCP. There are no vaccines in clinical trials for the prevention of PCP, and significant obstacles exist that have slowed development, including host range specificity, and the inability to culture Pneumocystis spp. in vitro. In this review, we overview the immune response to Pneumocystis spp., and discuss current progress on novel vaccines and therapies currently in the preclinical and clinical pipeline.

Investigating natural antibiofilm components: a new therapeutic perspective against candidal vulvovaginitis

The rampant emergence of Candida albicans in the vagina and its ability to thrive as a biofilm has outstood the prevalence of candidal vulvovaginitis (CVV), a gender-based fungal infection approximately affecting 75% of the global female population. The biofilm represents a multidimensional microbial population, which often dictates prominent caveats of CVV such as increased fungal virulence, drug resistance and infection relapse/recurrence. Additionally, the conjugated issues of the ineffectiveness of conventional antifungals (azoles), prolonged treatment durations, compromised patient compliance, economic and social burden, exacerbates CVV complications as well. Henceforth, the current hypothesis narrates an investigational proposal for exploration and combination of naturally derived antibiofilm components with luliconazole (imidazole antifungal agent) as a new therapeutic paradigm against CVV. The purported hypothesis unravels a synergistic approach for fabricating Nanostructured Lipid Carriers, NLCs loaded transvaginal gel with dual APIs of natural (antibiofilm) as well as the synthetic (antifungal) origin to target high therapeutic efficacy, delivery, retention, controlled release and bioadhesion in a vaginal milieu. The multipronged effect of antibiofilm and antifungal agents will expectably enhance drug susceptibility thus, maintaining Minimum Inhibitory Concentration (MIC) against cells of C. albicans and targeting its biofilm in planktonic, adherent, and sessile phases. The effective disruption of a biofilm could further lower infection resistance and recurrence as well. In conclusion, the purported hypothesis could speed up the emergence of novel drug combinations and accelerates new product development with solid, synergistic, and complementary activities against C. albicans and its biofilm, making it amenable for generating pre-clinical and clinical results therebycreating a suitableroadmap for commercialization.

Reversal of azole resistance in Candida albicans by oridonin

OBJECTIVES

Candida albicans is a yeast that causes fungal infections with high mortality and is typically resistant to azole drugs. To overcome this resistance, we explored the combined use of oridonin (ORI) and three azole drugs, namely fluconazole (FLC), itraconazole (ITR) and voriconazole (VOR). Azole-resistant C. albicans strains were obtained from cancer patients and the reversal of drug resistance in these strains was investigated.

METHODS

The synergistic antifungal activity of ORI and azole drugs was measured by checkerboard microdilution and time-kill assays. The resistance reversal mechanisms, namely inhibition of drug efflux and induction of apoptosis, were investigated by flow cytometry. Expression levels of the efflux pump-related genesCDR1 and CDR2 were assessed by RT-qPCR.

RESULTS

The efflux pump inhibition assay with ORI showed that the minimum inhibitory concentrations (MICs) of FLC (128-fold), ITR (64-fold) and VOR (250-fold) decreased significantly. Upregulation of genes encodingCDR1 and CDR2 was confirmed in the resistant strain. The sensitising effect of ORI on FLC in the treatment of C. albicans also included the promotion of apoptosis.

CONCLUSION

We demonstrated that combining azoles with ORI exerted potent synergism and that ORI could promote sensitisation to azoles in azole-resistantC. albicans. The discovery that ORI can effectively inhibit drug efflux and promote apoptosis may provide new insights and therapeutic strategies to overcome increasing azole resistance in C. albicans.

How to Use a Mutant Library to Identify Genes Required for Biofilm Formation in the Pathogenic Fungus Candida albicans

With over 1 billion infections and the causative agents showing critical diseases such as pancreatic cancer, the study of pathogenic fungi has never been more critical. In 2017, the United States spent $7.2 billion on fungal diseases. $4.5 billion was allocated to 75,055 hospitalizations, while $2.6 billion went to 8,993,230 outpatient visits. For Candida infections specifically, the cost was $1.4 billion. Currently, there are few classes of antifungals available, and resistance is growing. The identification of genes required for biofilm formation is essential for new antifungal development. This review details how to identify, verify, and characterize defective biofilm formation mutants in C. albicans. This includes how to run an in vitro biofilm formation assay, how to create clean deletions using the modified CRISPR-Cas9 system, how to assay to identify the potential causes of the defect, and how to create complementation strains to confirm the mutant defect.

Strategies to Better Target Fungal Squalene Monooxygenase

Fungal pathogens present a challenge in medicine and agriculture. They also harm ecosystems and threaten biodiversity. The allylamine class of antimycotics targets the enzyme squalene monooxygenase. This enzyme occupies a key position in the sterol biosynthesis pathway in eukaryotes, catalyzing the rate-limiting reaction by introducing an oxygen atom to the squalene substrate converting it to 2,3-oxidosqualene. Currently, terbinafine-the most widely used allylamine-is mostly used for treating superficial fungal infections. The ability to better target this enzyme will have significant implications for human health in the treatment of fungal infections. The human orthologue can also be targeted for cholesterol-lowering therapeutics and in cancer therapies. This review will focus on the structural basis for improving the current therapeutics for fungal squalene monooxygenase.

In Vitro and In Vivo Effect of Peptides Derived from 14-3-3 Paracoccidioides spp. Protein

Background: Paracoccidioidomycosis (PCM) is a chronic disease that causes sequelae and requires prolonged treatment; therefore, new therapeutic approaches are necessary. In view of this, three peptides from Paracoccidioides brasiliensis 14-3-3 protein were selected based on its immunogenicity and therapeutic potential. Methods: The in vitro antifungal activity and cytotoxicity of the 14-3-3 peptides were evaluated. The influence of the peptides in immunological and survival aspects was evaluated in vivo, using Galleria mellonella and the expression of antimicrobial peptide genes in Caenorhabditis elegans. Results: None of the peptides were toxic to HaCaT (skin keratinocyte), MRC-5 (lung fibroblast), and A549 (pneumocyte) cell lines, and only P1 exhibited antifungal activity against Paracoccidioides spp. The peptides could induce an immune response in G. mellonella. Moreover, the peptides caused a delay in the death of Paracoccidioides spp. infected larvae. Regarding C. elegans, the three peptides were able to increase the expression of the antimicrobial peptides. These peptides had essential effects on different aspects of Paracoccidioides spp. infection showing potential for a therapeutic vaccine. Future studies using mammalian methods are necessary to validate our findings.

Targeting Unconventional Pathways in Pursuit of Novel Antifungals

The impact of invasive fungal infections on human health is a serious, but largely overlooked, public health issue. Commonly affecting the immunocompromised community, fungal infections are predominantly caused by species of Candida, Cryptococcus, and Aspergillus. Treatments are reliant on the aggressive use of pre-existing antifungal drug classes that target the fungal cell wall and membrane. Despite their frequent use, these drugs are subject to unfavorable drug-drug interactions, can cause undesirable side-effects and have compromised efficacy due to the emergence of antifungal resistance. Hence, there is a clear need to develop novel classes of antifungal drugs. A promising approach involves exploiting the metabolic needs of fungi by targeted interruption of essential metabolic pathways. This review highlights potential antifungal targets including enolase, a component of the enolase-plasminogen complex, and enzymes from the mannitol biosynthesis and purine nucleotide biosynthesis pathways. There has been increased interest in the enzymes that comprise these particular pathways and further investigation into their merits as antifungal targets and roles in fungal survival and virulence are warranted. Disruption of these vital processes by targeting unconventional pathways with small molecules or antibodies may serve as a promising approach to discovering novel classes of antifungals.

Copper in infectious disease: Using both sides of the penny

The transition metal Cu is an essential micronutrient that serves as a co-factor for numerous enzymes involved in redox and oxygen chemistry. However, Cu is also a potentially toxic metal, especially to unicellular microbes that are in direct contact with their environment. Since 400 BCE, Cu toxicity has been leveraged for its antimicrobial properties and even today, Cu based materials are being explored as effective antimicrobials against human pathogens spanning bacteria, fungi, and viruses, including the SARS-CoV-2 agent of the 2019-2020 pandemic. Given that Cu has the double-edged property of being both highly toxic and an essential micronutrient, it plays an active and complicated role at the host-pathogen interface. Humans have evolved methods of incorporating Cu into innate and adaptive immune processes and both sides of the penny (Cu toxicity and Cu as a nutrient) are employed. Here we review the evolution of Cu in biology and its multi-faceted roles in infectious disease, from the viewpoints of the microbial pathogens as well as the animal hosts they infect.

Fungal Extracellular Vesicles in Pathophysiology

Fungal pathogens are a concern in medicine and agriculture that has been exacerbated by the emergence of antifungal-resistant varieties that severely threaten human and animal health, as well as food security. This had led to the search for new and sustainable treatments for fungal diseases. Innovative solutions require a deeper understanding of the interactions between fungal pathogens and their hosts, and the key determinants of fungal virulence. Recently, a link has emerged between the release of extracellular vesicles (EVs) and fungal virulence that may contribute to finding new methods for fungal control. Fungal EVs carry pigments, carbohydrates, protein, nucleic acids and other macromolecules with similar functions as those found in EVs from other organisms, however certain fungal features, such as the fungal cell wall, impact EV release and cargo. Fungal EVs modulate immune responses in the host, have a role in cell-cell communication and transport molecules that function in virulence. Understanding the function of fungal EVs will expand our knowledge of host-pathogen interactions and may provide new and specific targets for antifungal drugs and agrichemicals.

Mechanistic insights into Candida biofilm eradication potential of eucalyptol

AIM

Candida-associated fungal infections are prevalent in hospitalized and immune-compromised patients. Their biofilm architecture and high rate of antifungal resistance make treatment challenging. Eucalyptol (EPTL), a monoterpene majorly present in the essential oil of eucalyptus is well known for curing respiratory infections. Hence, the present study investigated the anti-biofilm efficacy of EPTL against the laboratory strains and clinical isolates of Candida to delineate its mode of action.

METHODS

The effect of EPTL on the viability, biofilm formation, and mature biofilm of Candida strains was studied. Furthermore, its effect on cell cycle arrest, mitochondrial membrane potential (MMP), ROS generation, germ tube formation, ergosterol content and transcriptional expression of selected genes was also investigated.

RESULTS

EPTL exhibited anti-biofilm activity against mature and developing biofilm of Candida albicans and Candida glabrata along with their clinical isolates. The biochemical components and enzyme activity were differentially modulated in EPTL-treated biofilm extracellular matrix. EPTL generated ROS and arrested cell cycle at the G₁ /S phase in both the species, while altered MMP was recorded in C. glabrata. Transcriptional analysis evidenced for differential gene expression of selected ABC transporters, secreted hydrolytic enzymes, and cell wall biogenesis in C. albicans/C. glabrata upon treating with EPTL.

CONCLUSION

The current data on anti-biofilm activity of EPTL establish its candidacy for drug development or as an adjuvant with existing antifungal formulations.

SIGNIFICANCE AND IMPACT OF THE STUDY

Present investigation elucidates the mode of action of Eucalyptol as antifungal agent and would stand as a candidate for management of topical fungal infection.

The global, regional, and national burden of fungal skin diseases in 195 countries and territories: A cross-sectional analysis from the Global Burden of Disease Study 2017

Introduction

Fungal skin diseases are highly prevalent worldwide, but few existing studies focus on the burden of dermatomycoses.

Methods

An analysis of fungal skin disease trends in 2017 in 195 countries worldwide was conducted using the Global Burden of Disease Study database, including prevalence rates, age and sex patterns, and fungal burden, using disability-adjusted life years (DALYs). Age-standardized DALYs were also compared to the sociodemographic index values of all the countries in 2017.

Results

The age-specific fungal skin disease DALYs in 2017 showed a right-skewed distribution, with a peak between 1 and 5 years of age. The world region with the greatest burden of fungal skin disease was sub-Saharan Africa (DALY rate 89.3 per 100,000 males, 78.42 for females), and the individual country with the greatest DALY rate was Mali (122). The Global Burden of Disease super region with the lowest fungal skin disease burden had high incomes (DALY rate 33.12 per 100,000 males, 30.16 for females), which includes southern Latin America, western Europe, high-income North America, Australasia, and high-income southern Pacific.

Conclusion

Skin mycoses place a substantial burden on patients worldwide. This burden is the greatest in resource-poor countries, tropical regions, and children between 1 and 5 years of age. DALYs can potentially serve as a purposeful measure for directing health policy resources to improve the global impact of fungal skin disease.

Multiplex PCR Based Strategy for Detection of Fungal Pathogen DNA in Patients with Suspected Invasive Fungal Infections

A new and easy polymerase chain reaction (PCR) multiplex strategy, for the identification of the most common fungal species involved in invasive fungal infections (IFI) was developed in this work. Two panels with species-specific markers were designed, the Candida Panel for the identification of Candida species, and the Filamentous Fungi Panel for the identification of Aspergillus species and Rhizopusarrhizus. The method allowed the correct identification of all targeted pathogens using extracted DNA or by colony PCR, showed no cross-reactivity with nontargeted species and allowed identification of different species in mixed infections. Sensitivity reached 10 to 1 pg of DNA and was suitable for clinical samples from sterile sites, with a sensitivity of 89% and specificity of 100%. Overall, the study showed that the new method is suitable for the identification of the ten most important fungal species involved in IFI, not only from positive blood cultures but also from clinical samples from sterile sites. The method provides a unique characteristic, of seeing the peak in the specific region of the panel with the correct fluorescence dye, that aids the ruling out of unspecific amplifications. Furthermore, the panels can be further customized, selecting markers for different species and/or resistance genes.

Nanopore Sequencing of the Fungal Intergenic Spacer Sequence as a Potential Rapid Diagnostic Assay

Fungal infections are being caused by a broadening spectrum of fungi, yet in many cases, identification to the species level is required for proper antifungal selection. We investigated the fungal intergenic spacer (IGS) sequence in combination with nanopore sequencing for fungal identification. We sequenced isolates from two Cryptococcus species complexes, C. gattii and C. neoformans, which are the main pathogenic members of this genus, using the Oxford Nanopore Technologies MinION device and Sanger sequencing. There is enough variation within the two complexes to argue for further resolution into separate species, which we wanted to see if nanopore sequencing could detect. Using the R9.4.1 flow cell, IGS sequence identities averaged 99.57% compared to Sanger sequences of the same region. When the newer R10.3 flow cell was used, accuracy increased to 99.83% identity compared to the same Sanger sequences. Nanopore sequencing errors were predominantly in regions of homopolymers, with G homopolymers displaying the largest number of errors and C homopolymers displaying the least. Phylogenetic analysis of the nanopore- and Sanger-derived sequences resulted in indistinguishable trees. Comparison of average percent identities between the C. gattii and C. neoformans species complexes resulted in only a 74 to 77% identity between the two complexes. Sequencing using the nanopore platform could be completed in less than an hour, and samples could be multiplexed in groups as large as 24 sequences in a single run. These results suggest that sequencing the IGS region using nanopore sequencing could be a potential new molecular diagnostic strategy.

Candidemia in pediatric burn patients: Risk factors and outcomes in a retrospective cohort study

Background and Purpose :

Despite advances in burn care and management, infections are still a major contributor to morbidity and mortality rates in patients with burn injuries. Regarding this, the present study was conducted to investigate the prevalence and importance of candidemia in pediatric burn patients.

Materials and Methods:

Blood samples were collected from the patients and cultured in an automated blood culture system. Candida species were identified using specific culture media. The relationship between candidemia and possible risk factors was evaluated and compared to a control group.

Results:

A total of 71 patients with the mean age of 4.52±3.63 years were included in the study. Blood cultures showed candidemia in 19 (27%) patients. Based on the results, C. albicans was the most common fungus among patients with and without candidemia. The results of statistical analysis also showed that candidemia was significantly correlated with total body surface area (TBSA), mechanical ventilation, duration of total parenteral nutrition, length of intensive care unit (ICU) stay, presence of neutropenia, and R-Baux score (all P≤0.001). In this regard, TBSA, length of ICU stay, R-Baux score, and Candida score were identified as the determinant factors for mortality due to candidemia.

Conclusion:

Candidemia increases the mortality and morbidity rates associated with burn injuries. Prompt diagnostic and prevention measures can reduce the unfortunate outcomes via controlling the possible risk factors.

Identifying candidate Aspergillus pathogenicity factors by annotation frequency

BACKGROUND

Members of the genus Aspergillus display a variety of lifestyles, ranging from saprobic to pathogenic on plants and/or animals. Increased genome sequencing of economically important members of the genus permits effective use of "-omics" comparisons between closely related species and strains to identify candidate genes that may contribute to phenotypes of interest, especially relating to pathogenicity. Protein-coding genes were predicted from 216 genomes of 12 Aspergillus species, and the frequencies of various structural aspects (exon count and length, intron count and length, GC content, and codon usage) and functional annotations (InterPro, Gene Ontology, and Kyoto Encyclopedia of Genes and Genomes terms) were compared.

RESULTS

Using principal component analyses, the three sets of functional annotations for each strain were clustered by species. The species clusters appeared to separate by pathogenicity on plants along the first dimensions, which accounted for over 20% of the variance. More annotations for genes encoding pectinases and secondary metabolite biosynthetic enzymes were assigned to phytopathogenic strains from species such as Aspergillus flavus. In contrast, Aspergillus fumigatus strains, which are pathogenic to animals but not plants, were assigned relatively more terms related to phosphate transferases, and carbohydrate and amino-sugar metabolism. Analyses of publicly available RNA-Seq data indicated that one A. fumigatus protein among 17 amino-sugar processing candidates, a hexokinase, was up-regulated during co-culturing with human immune system cells.

CONCLUSION

Genes encoding hexokinases and other proteins of interest may be subject to future manipulations to further refine understanding of Aspergillus pathogenicity factors.

Host Defense Peptides as Templates for Antifungal Drug Development

Current treatment for invasive fungal diseases is limited to three classes of antifungal drugs: azoles, polyenes, and echinocandins. The most recently introduced antifungal class, the echinocandins, was first approved nearly 30 years ago. The limited antifungal drug portfolio is rapidly losing its clinical utility due to the inexorable rise in the incidence of invasive fungal infections and the emergence of multidrug resistant (MDR) fungal pathogens. New antifungal therapeutic agents and novel approaches are desperately needed. Here, we detail attempts to exploit the antifungal and immunoregulatory properties of host defense peptides (HDPs) in the design and evaluation of new antifungal therapeutics and discuss historical limitations and recent advances in this quest.

Mucosal IgA Prevents Commensal Candida albicans Dysbiosis in the Oral Cavity

The fungus Candida albicans colonizes the oral mucosal surface of 30–70% of healthy individuals. Due to local or systemic immunosuppression, this commensal fungus is able to proliferate resulting in oral disease, called oropharyngeal candidiasis (OPC). However, in healthy individuals C. albicans causes no harm. Unlike humans mice do not host C. albicans in their mycobiome. Thus, oral fungal challenge generates an acute immune response in a naive host. Therefore, we utilized C. albicans clinical isolates which are able to persist in the oral cavity without causing disease to analyze adaptive responses to oral fungal commensalism. We performed RNA sequencing to determine the transcriptional host response landscape during C. albicans colonization. Pathway analysis revealed an upregulation of adaptive host responses due to C. albicans oral persistence, including the upregulation of the immune network for IgA production. Fungal colonization increased cross-specific IgA levels in the saliva and the tongue, and IgA⁺ cells migrated to foci of fungal colonization. Binding of IgA prevented fungal epithelial adhesion and invasion resulting in a dampened proinflammatory epithelial response. Besides CD19⁺ CD138⁻ B cells, plasmablasts, and plasma cells were enriched in the tongue of mice colonized with C. albicans suggesting a potential role of B lymphocytes during oral fungal colonization. B cell deficiency increased the oral fungal load without causing severe OPC. Thus, in the oral cavity B lymphocytes contribute to control commensal C. albicans carriage by secreting IgA at foci of colonization thereby preventing fungal dysbiosis.

Variation Among Biosynthetic Gene Clusters, Secondary Metabolite Profiles, and Cards of Virulence Across Aspergillus Species

Aspergillus fumigatus is a major human pathogen. In contrast, Aspergillus fischeri and the recently described Aspergillus oerlinghausenensis, the two species most closely related to A. fumigatus, are not known to be pathogenic. Some of the genetic determinants of virulence (or "cards of virulence") that A. fumigatus possesses are secondary metabolites that impair the host immune system, protect from host immune cell attacks, or acquire key nutrients. To examine whether secondary metabolism-associated cards of virulence vary between these species, we conducted extensive genomic and secondary metabolite profiling analyses of multiple A. fumigatus, one A. oerlinghausenensis, and multiple A. fischeri strains. We identified two cards of virulence (gliotoxin and fumitremorgin) shared by all three species and three cards of virulence (trypacidin, pseurotin, and fumagillin) that are variable. For example, we found that all species and strains examined biosynthesized gliotoxin, which is known to contribute to virulence, consistent with the conservation of the gliotoxin biosynthetic gene cluster (BGC) across genomes. For other secondary metabolites, such as fumitremorgin, a modulator of host biology, we found that all species produced the metabolite but that there was strain heterogeneity in its production within species. Finally, species differed in their biosynthesis of fumagillin and pseurotin, both contributors to host tissue damage during invasive aspergillosis. A. fumigatus biosynthesized fumagillin and pseurotin, while A. oerlinghausenensis biosynthesized fumagillin and A. fischeri biosynthesized neither. These biochemical differences were reflected in sequence divergence of the intertwined fumagillin/pseurotin BGCs across genomes. These results delineate the similarities and differences in secondary metabolism-associated cards of virulence between a major fungal pathogen and its nonpathogenic closest relatives, shedding light onto the genetic and phenotypic changes associated with the evolution of fungal pathogenicity.

Sphaerostilbellins, New Antimicrobial Aminolipopeptide Peptaibiotics from Sphaerostilbella toxica

Sphaerostilbella toxica is a mycoparasitic fungus that can be found parasitizing wood-decay basidiomycetes in the southern USA. Organic solvent extracts of fermented strains of S. toxica exhibited potent antimicrobial activity, including potent growth inhibition of human pathogenic yeasts Candida albicans and Cryptococcus neoformans, the respiratory pathogenic fungus Aspergillus fumigatus, and the Gram-positive bacterium Staphylococcus aureus. Bioassay-guided separations led to the purification and structure elucidation of new peptaibiotics designated as sphaerostilbellins A and B. Their structures were established mainly by analysis of NMR and HRMS data, verification of amino acid composition by Marfey's method, and by comparison with published data of known compounds. They incorporate intriguing structural features, including an N-terminal 2-methyl-3-oxo-tetradecanoyl (MOTDA) residue and a C-terminal putrescine residue. The minimal inhibitory concentrations for sphaerostilbellins A and B were measured as 2 μM each for C. neoformans, 1 μM each for A. fumigatus, and 4 and 2 μM, respectively, for C. albicans. Murine macrophage cells were unaffected at these concentrations.

Public Awareness of Invasive Fungal Diseases - United States, 2019

Fungal diseases range from minor skin and mucous membrane infections to life-threatening disseminated disease. The estimated yearly direct health care costs of fungal diseases exceed $7.2 billion (1). These diseases are likely widely underdiagnosed (1,2), and improved recognition among health care providers and members of the public is essential to reduce delays in diagnoses and treatment. However, information about public awareness of fungal diseases is limited. To guide public health educational efforts, a nationally representative online survey was conducted to assess whether participants had ever heard of six invasive fungal diseases. Awareness was low and varied by disease, from 4.1% for blastomycosis to 24.6% for candidiasis. More than two thirds (68.9%) of respondents had never heard of any of the diseases. Female sex, higher education, and increased number of prescription medications were associated with awareness. These findings can serve as a baseline to compare with future surveys; they also indicate that continued strategies to increase public awareness about fungal diseases are needed.

First Report of Candidemia Clonal Outbreak Caused by Emerging Fluconazole-Resistant Candida parapsilosis Isolates Harboring Y132F and/or Y132F+K143R in Turkey

Clonal outbreaks of fluconazole-resistant (FLZR) Candida parapsilosis isolates have been reported in several countries. Despite its being the second leading cause of candidemia, the azole resistance mechanisms and the clonal expansion of FLZR C. parapsilosis blood isolates have not been reported in Turkey. In this study, we consecutively collected C. parapsilosis blood isolates (n = 225) from the fifth largest hospital in Turkey (2007 to 2019), assessed their azole susceptibility pattern using CLSI M27-A3/S4, and sequenced ERG11 for all and MRR1, TAC1, and UPC2 for a selected number of C. parapsilosis isolates. The typing resolution of two widely used techniques, amplified fragment length polymorphism typing (AFLP) and microsatellite typing (MST), and the biofilm production of FLZR isolates with and without Y132F were compared. Approximately 27% of isolates were FLZR (60/225), among which 90% (54/60) harbored known mutations in Erg11, including Y132F (24/60) and Y132F+K143R (19/60). Several mutations specific to FLZR isolates were found in MRR1, TAC1, and UPC2 AFLP grouped isolates into two clusters, while MST revealed several clusters. The majority of Y132F/Y132F+K143R isolates grouped in clonal clusters, which significantly expanded throughout 2007 to 2019 in neonatal wards. Candida parapsilosis isolates carrying Y132F were associated with significantly higher mortality and less biofilm production than other FLZR isolates. Collectively, we documented the first outbreak of FLZR C. parapsilosis blood isolates in Turkey. The MRR1, TAC1, and UPC2 mutations exclusively found in FLZR isolates establishes a basis for future studies, which will potentially broaden our knowledge of FLZR mechanisms in C. parapsilosis MST should be a preferred method for clonal analysis of C. parapsilosis isolates in outbreak scenarios.

Therapies and Vaccines Based on Nanoparticles for the Treatment of Systemic Fungal Infections

Treatment modalities for systemic mycoses are still limited. Currently, the main antifungal therapeutics include polyenes, azoles, and echinocandins. However, even in the setting of appropriate administration of antifungals, mortality rates remain unacceptably high. Moreover, antifungal therapy is expensive, treatment periods can range from weeks to years, and toxicity is also a serious concern. In recent years, the increased number of immunocompromised individuals has contributed to the high global incidence of systemic fungal infections. Given the high morbidity and mortality rates, the complexity of treatment strategies, drug toxicity, and the worldwide burden of disease, there is a need for new and efficient therapeutic means to combat invasive mycoses. One promising avenue that is actively being pursued is nanotechnology, to develop new antifungal therapies and efficient vaccines, since it allows for a targeted delivery of drugs and antigens, which can reduce toxicity and treatment costs. The goal of this review is to discuss studies using nanoparticles to develop new therapeutic options, including vaccination methods, to combat systemic mycoses caused by Candida sp., Cryptococcus sp., Paracoccidioides sp., Histoplasma sp., Coccidioides sp., and Aspergillus sp., in addition to providing important information on the use of different types of nanoparticles, nanocarriers and their corresponding mechanisms of action.

Interactions of microorganisms with host mucins: a focus on Candida albicans

Mucus is an important host innate defense factor that lines most epithelial cell layers of the body and provides crucial physical and biological protection against pathogenic microorganisms. Mucins are the main glycoproteins of mucus that are responsible for interacting with microorganisms and are critical for the antimicrobial properties of mucus. The mechanisms by which microorganisms interact with mucins are poorly understood, especially in terms of fungi, and these interactions are continually evolving. Work in bacterial pathogens has shown that mucins inhibit bacterial virulence traits, including quorum sensing, toxin secretion and biofilm formation. Among the fungal clade, the common opportunistic human fungal pathogen and commensal Candida albicans engages in constant battle with the host innate immune system. This battle creates strong selective pressures for C. albicans to evolve in response to the host. Recent work in C. albicans found that mucins inhibit specific virulence traits, such as surface adherence, filamentation, biofilm formation and the production of secreted proteases. Here we review the current knowledge of microbial interactions with mucins, with a special emphasis on the interactions between C. albicans and mucins.

Identification of the Antifungal Metabolite Chaetoglobosin P From Discosia rubi Using a Cryptococcus neoformans Inhibition Assay: Insights Into Mode of Action and Biosynthesis

Cryptococcus neoformans is an important human pathogen with limited options for treatments. We have interrogated extracts from fungal fermentations to find Cryptococcus-inhibiting natural products using assays for growth inhibition, differential thermosensitivity, and synergy with existing antifungal drugs. Extracts from fermentations of strains of Discosia rubi from eastern Texas showed anticryptococcal bioactivity with preferential activity in agar zone of inhibition assays against C. neoformans at 37°C versus 25°C. Assay-guided fractionation led to the purification and identification of chaetoglobosin P as the active component of these extracts. Genome sequencing of these strains revealed a biosynthetic gene cluster consistent with chaetoglobosin biosynthesis and β-methylation of the tryptophan residue. Proximity of genes of the actin-binding protein twinfilin-1 to the chaetoglobosin P and K gene clusters suggested a possible self-resistance mechanism involving twinfilin-1 which is consistent with the predicted mechanism of action involving interference with the polymerization of the capping process of filamentous actin. A C. neoformans mutant lacking twinfilin-1 was hypersensitive to chaetoglobosin P. Chaetoglobosins also potentiated the effects of amphotericin B and caspofungin on C. neoformans.