Prevalence of voriconazole-resistant invasive aspergillosis and its impact on mortality in haematology patients

Epidermal growth factor receptor signaling governs the host inflammatory response to invasive aspergillosis

The epidermal growth factor receptor (EGFR) has been identified as an epithelial cell receptor for Mucorales fungi and Candida albicans. Blocking EGFR with small molecule inhibitors reduces disease severity in mouse models of mucormycosis and oropharyngeal candidiasis. In contrast, cases of invasive aspergillosis have been reported in cancer patients who were treated with EGFR inhibitors, suggesting that EGFR signaling may play a protective role in the host defense against this infection. Here, we analyzed transcriptomic data from the lungs of mice with invasive aspergillosis and found evidence that Aspergillus fumigatus infection activates multiple genes that are predicted to function in the EGFR signaling pathway. We also found that A. fumigatus infection activates EGFR in both a human small-airway epithelial (HSAE) cell line and in the lungs of immunosuppressed mice. EGFR signaling in HSAE cells is required for maximal endocytosis of A. fumigatus and for fungal-induced proinflammatory cytokine and chemokine production. In a corticosteroid immunosuppressed mouse model of invasive pulmonary aspergillosis, inhibition of EGFR with gefitinib decreased whole-lung cytokine and chemokine levels and reduced accumulation of phagocytes in the lung, leading to a decrease in fungal killing, an increase in pulmonary fungal burden, and accelerated mortality. Thus, EGFR signaling is required for pulmonary epithelial cells to orchestrate the host innate immune defense against invasive aspergillosis in immunosuppressed hosts.IMPORTANCEWhen A. fumigatus infects the lungs, it invades epithelial cells that line the airways. During this process, the fungus interacts with epithelial cell receptors. This interaction stimulates epithelial cells to endocytose the fungus. It also induces these cells to secrete proinflammatory cytokines and chemokines that recruit phagocytes to the site of infection where they can kill the fungus. Here, we show that in small-airway epithelial cells, the EGFR acts as a sensor for A. fumigatus that triggers the production of chemokines in response to fungal infection. In corticosteroid-immunosuppressed mice, blocking EGFR with the kinase inhibitor gefitinib reduces chemokine production in the lungs. This leads to decreased accumulation of neutrophils and dendritic cells in the lungs, reduced A. fumigatus killing, and increased mortality. These results provide a potential explanation as to why some cancer patients who are treated with EGFR inhibitors develop invasive aspergillosis.

Understanding the clinical and environmental drivers of antifungal resistance in the One Health context

Antifungal drugs have had a tremendous impact on human health and the yields of crops. However, in recent years, due to usage both in a health setting and in agriculture, there has been a rapid emergence of antifungal drug resistance that has outpaced novel compound discovery. It is now globally recognized that new strategies to tackle fungal infection are urgently needed, with such approaches requiring the cooperation of both sectors and the development of robust antifungal stewardship rationales. In this review, we examine the current antifungal regimes in clinical and agricultural settings, focusing on two pathogens of importance, Candida auris and Aspergillus fumigatus, examining their drivers of antifungal resistance, the impact of dual-use azoles and the impact agricultural practices have on driving the emergence of resistance. Finally, we postulate that a One Health approach could offer a viable alternative to prolonging the efficacy of current antifungal agents.

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

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Epidermal Growth Factor Receptor Signaling Governs the Host Inflammatory Response to Invasive Aspergillosis

The epidermal growth factor receptor (EGFR) has been identified as an epithelial cell receptor for Mucorales fungi and Candida albicans. Blocking EGFR with small molecule inhibitors reduces disease severity in mouse models of mucormycosis and oropharyngeal candidiasis. In contrast, cases of invasive aspergillosis have been reported in cancer patients who were treated with EGFR inhibitors, suggesting that EGFR signaling may play a protective role in the host defense against this infection. Here, we analyzed transcriptomic data from the lungs of mice with invasive aspergillosis and found evidence that Aspergillus fumigatus infection activates multiple genes that are predicted to function in the EGFR signaling pathway. We also found that A. fumigatus infection activates EGFR in both a human small airway epithelial (HSAE) cell line and in the lungs of immunosuppressed mice. EGFR signaling in HSAE cells is required for maximal endocytosis of A. fumigatus and for fungal-induced proinflammatory cytokine and chemokine production. In a corticosteroid immunosuppressed mouse model of invasive pulmonary aspergillosis, inhibition of EGFR with gefitinib decreased whole lung chemokine levels and reduced accumulation of phagocytes in the lung, leading to a decrease in fungal killing, an increase in pulmonary fungal burden, and accelerated mortality. Thus, EGFR signaling is required for pulmonary epithelial cells to orchestrate the host innate immune defense against invasive aspergillosis in immunosuppressed hosts.

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

BACKGROUND

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

OBJECTIVES

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

SOURCES

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

CONTENT

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

IMPLICATIONS

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

Aspergillus fumigatus-a systematic review to inform the World Health Organization priority list of fungal pathogens

Recognizing the growing global burden of fungal infections, the World Health Organization established a process to develop a priority list of fungal pathogens (FPPL). In this systematic review, we aimed to evaluate the epidemiology and impact of invasive infections caused by Aspergillus fumigatus to inform the first FPPL. The pre-specified criteria of mortality, inpatient care, complications and sequelae, antifungal susceptibility, risk factors, preventability, annual incidence, global distribution, and emergence were used to search for relevant articles between 1 January 2016 and 10 June 2021. Overall, 49 studies were eligible for inclusion. Azole antifungal susceptibility varied according to geographical regions. Voriconazole susceptibility rates of 22.2% were reported from the Netherlands, whereas in Brazil, Korea, India, China, and the UK, voriconazole susceptibility rates were 76%, 94.7%, 96.9%, 98.6%, and 99.7%, respectively. Cross-resistance was common with 85%, 92.8%, and 100% of voriconazole-resistant A. fumigatus isolates also resistant to itraconazole, posaconazole, and isavuconazole, respectively. The incidence of invasive aspergillosis (IA) in patients with acute leukemia was estimated at 5.84/100 patients. Six-week mortality rates in IA cases ranged from 31% to 36%. Azole resistance and hematological malignancy were poor prognostic factors. Twelve-week mortality rates were significantly higher in voriconazole-resistant than in voriconazole-susceptible IA cases (12/22 [54.5%] vs. 27/88 [30.7%]; P = .035), and hematology patients with IA had significantly higher mortality rates compared with solid-malignancy cases who had IA (65/217 [30%] vs. 14/78 [18%]; P = .04). Carefully designed surveillance studies linking laboratory and clinical data are required to better inform future FPPL.

Epidemiology and Azole Resistance of Clinical Isolates of Aspergillus fumigatus from a Large Tertiary Hospital in Ningxia, China

Purpose

The objective of this study was to determine the clinical distribution, in vitro antifungal susceptibility and underlying resistance mechanisms of Aspergillus fumigatus (A. fumigatus) isolates from the General Hospital of Ningxia Medical University between November 2021 and May 2023.

Methods

Antifungal susceptibility testing was performed using the Sensititre YeastOne YO10, and isolates with high minimal inhibitory concentrations (MICs) were further confirmed using the standard broth microdilution assays established by the Clinical and Laboratory Standards Institute (CLSI) M38-third edition. Whole-Genome Resequencing and RT-qPCR in azole-resistant A. fumigatus strains were performed to investigate the underlying resistance mechanisms.

Results

Overall, a total of 276 A. fumigatus isolates were identified from various clinical departments, showing an increasing trend in the number of isolates over the past 3 years. Two azole-resistant A. fumigatus strains (0.72%) were observed, one of which showed overexpression of cyp51A, cyp51B, cdr1B, MDR1/2, artR, srbA, erg24A, and erg4B, but no cyp51A mutation. However, the other strain harbored two alterations in the cyp51A sequences (L98H/S297T). Therefore, we first described two azole-resistant clinical A. fumigatus strains in Ningxia, China, and reported one azole-resistant strain that has the L98H/S297T mutations in the cyp51A gene without any tandem repeat (TR) sequences in the promoter region.

Conclusions

This study emphasizes the importance of enhancing attention and surveillance of azole-resistant A. fumigatus, particularly those with non-TR point mutations of cyp51A or non-cyp51A mutations, in order to gain a better understanding of their prevalence and spread in the region.

Antifungal Resistance in Pulmonary Aspergillosis

Aspergilli may cause various pulmonary diseases in humans, including allergic bronchopulmonary aspergillosis (ABPA), chronic pulmonary aspergillosis (CPA), and acute invasive pulmonary aspergillosis (IPA). In addition, chronic colonization may occur in cystic fibrosis (CF). Aspergillus fumigatus represents the main pathogen, which may employ different morphotypes, for example, conidia, hyphal growth, and asexual sporulation, in the various Aspergillus diseases. These morphotypes determine the ease by which A. fumigatus can adapt to stress by antifungal drug exposure, usually resulting in one or more resistance mutations. Key factors that enable the emergence of resistance include genetic variation and selection. The ability to create genetic variation depends on the reproduction mode, including, sexual, parasexual, and asexual, and the population size. These reproduction cycles may take place in the host and/or in the environment, usually when specific conditions are present. Environmental resistance is commonly characterized by tandem repeat (TR)-mediated mutations, while in-host resistance selection results in single-resistance mutations. Reported cases from the literature indicate that environmental resistance mutations are almost exclusively present in patients with IA indicating that the risk for in-host resistance selection is very low. In aspergilloma, single-point mutations are the dominant resistance genotype, while in other chronic Aspergillus diseases, for example, ABPA, CPA, and CF, both TR-mediated and single-resistance mutations are reported. Insights into the pathogenesis of resistance selection in various Aspergillus diseases may help to improve diagnostic and therapeutic strategies.

Powerful and Real-Time Quantification of Antifungal Efficacy against Triazole-Resistant and -Susceptible Aspergillus fumigatus Infections in Galleria mellonella by Longitudinal Bioluminescence Imaging

Aspergillus fumigatus is an environmental mold that causes life-threatening respiratory infections in immunocompromised patients. The plateaued effectiveness of antifungal therapy and the increasing prevalence of triazole-resistant isolates have led to an urgent need to optimize and expand the current treatment options. For the transition of in vitro research to in vivo models in the time- and resource-consuming preclinical drug development pipeline, Galleria mellonella larvae have been introduced as a valuable in vivo screening intermediate. Despite the high potential of this model, the current readouts of fungal infections in G. mellonella are insensitive, irreproducible, or invasive. To optimize this model, we aimed for the longitudinal quantification of the A. fumigatus burden in G. mellonella using noninvasive bioluminescence imaging (BLI). Larvae were infected with A. fumigatus strains expressing a red-shifted firefly luciferase, and the substrate dosage was optimized for the longitudinal visualization of the fungal burden without affecting larval health. The resulting photon flux was successfully validated for fungal quantification against colony forming units (CFU) analyses, which revealed an increased dynamic range from BLI detection. Comparison of BLI to survival rates and health index scores additionally revealed improved sensitivity for the early discrimination of differences in fungal burdens as early as 1 day after infection. This was confirmed by the improved detection of treatment efficacy against triazole-susceptible and -resistant strains. In conclusion, we established a refined G. mellonella aspergillosis model that enables the noninvasive real-time quantification of A. fumigatus by BLI. This model provides a quick and reproducible in vivo system for the evaluation of treatment options and is in line with 3Rs recommendations. IMPORTANCE Triazole-resistant Aspergillus fumigatus strains are rapidly emerging, and resistant infections are difficult to treat, causing mortality rates of up to 88%. The recent WHO priority list underscores A. fumigatus as one of the most critical fungal pathogens for which innovative antifungal treatment should be (urgently) prioritized. Here, we deliver a Galleria mellonella model for triazole-susceptible and -resistant A. fumigatus infections combined with a statistically powerful quantitative, longitudinal readout of the A. fumigatus burden for optimized preclinical antifungal screening. G. mellonella larvae are a convenient invertebrate model for in vivo antifungal screenings, but so far, the model has been limited by variable and insensitive observational readouts. We show that bioluminescence imaging-based fungal burden quantification outperforms these readouts in reliability, sensitivity, and time to the detection of treatment effects in both triazole-susceptible and -resistant infections and can thus lead to better translatability from in vitro antifungal screening results to in vivo confirmation in mouse and human studies.

Establishment of a mathematical prediction model for voriconazole stable maintenance dose: a prospective study

Background

In patients with invasive fungal infection (IFI), the steady-state serum trough concentration (C min) of voriconazole (VCZ) is highly variable and can lead to treatment failure (C min < 0.5 mg/L) and toxicity (C min ≥ 5.0 mg/L). However, It remains challenging to determine the ideal maintenance dose to achieve the desired C min level quickly.

Aims

This randomized, prospective observational single-center study aimed to identify factors affecting VCZ-C min and maintenance dose and create an algorithmic model to predict the necessary maintenance dose. MeThe study enrolled 306 adult IFI patients, split into two groups: non-gene-directed (A) (where CYP2C19 phenotype is not involved in determining VCZ dose) and gene-directed (B) (where CYP2C19 phenotype is involved in determining VCZ dose).

Results

Results indicated that CYP2C19 genetic polymorphisms might significantly impact VCZ loading and maintenance dose selection. CYP2C19 phenotype, C-reaction protein (CRP), and average daily dose/body weight were significant influencers on VCZ-C min, while CYP2C19 phenotype, CRP, and body weight significantly impacted VCZ maintenance dose. A feasible predictive formula for VCZ stable maintenance dose was derived from the regression equation as a maintenance dose (mg) =282.774-0.735×age (year)+2.946×body weight(Kg)-19.402×CYP2C19 phenotype (UM/RM/NM:0, IM:1, PM:2)-0.316×CRP (mg/L) (p < 0.001).

Discussion

DiThis formula may serve as a valuable supplement to the Clinical Pharmacogenetics Implementation Consortium (CPIC®) guideline for CYP2C19 and VCZ therapy, especially for IFI patients with highly variable inflammatory cytokines during VCZ therapy.

First Report of Azole-Resistant Aspergillus fumigatus with TR46/Y121F/T289A Mutations in Kuwait and an Update on Their Occurrence in the Middle East

Pulmonary aspergillosis is a common fungal infection with several clinical manifestations including invasive, allergic and chronic chest diseases. Invasive pulmonary aspergillosis (IPA) is a leading cause of death in immunocompromised patients, particularly those receiving chemotherapy and among bone marrow transplant recipients. Aspergillus fumigatus is the most prevalent causative agent and voriconazole is the first-line therapy for IPA. In this study, we report the first isolation of voriconazole-resistant A. fumigatus carrying TR46/Y121F/T289A mutations from an immunocompromised pregnant lady in Kuwait. The patient was successfully treated for a probable respiratory infection with caspofungin and voriconazole. The literature review from PubMed has identified itraconazole-resistant clinical and environmental A. fumigatus isolates with TR34/L98H mutations in the cyp51A from several Middle Eastern countries including Kuwait. However, clinical A. fumigatus isolates with cyp51A TR46/Y121F/T289A mutations have not been reported previously from any country in the region while environmental isolates have been reported only from Iran. The source of voriconazole-resistant A. fumigatus CYP51A TR46/Y121F/T289A mutant in our patient remained unknown. Surveillance for azole resistance among clinical and environmental isolates of A. fumigatus is warranted in Kuwait.

Comparison of the Micronaut-AM System and the EUCAST Broth Microdilution Reference Method for MIC Determination of Four Antifungals against Aspergillus fumigatus

The Antifungal Susceptibility Testing method of the European Committee on Antimicrobial Susceptibility Testing (EUCAST-AFST) is a reference technique for the determination of the Minimum Inhibitory Concentration (MIC) of antifungals for Aspergillus fumigatus. However, it is time-consuming and requires expertise. Micronaut-AM (M-AM) is a fast, simple, time-saving, and ready-to-use new colorimetric method using an indicator (resazurin) to facilitate the visual reading. The aim of this retrospective study was to evaluate the performance of the M-AM system and compare it with the EUCAST broth microdilution reference method to determine the susceptibility of 77 A. fumigatus clinical strains to amphotericin B, itraconazole, voriconazole, and posaconazole. Overall, the essential agreements within ±2 dilutions were 100%, 62%, 58%, and 30% and the categorical agreements were 100%, 97%, 91%, and 87% for amphotericin B, itraconazole, voriconazole, and posaconazole, respectively. No categorical discrepancy was found for amphotericin B, but several categorical discordances were observed with azole antifungals. However, only 2 of the 16 azole-resistant strains confirmed by the cyp51A sequencing would have been misclassified by M-AM. The use of M-AM is probably suitable for the determination of the MICs of amphotericin B, but further evaluations are needed to confirm its usefulness for the determination of the MICs of azoles for A. fumigatus.

Invasive Aspergillosis and the Impact of Azole-resistance

Purpose of Review

IA (invasive aspergillosis) caused by azole-resistant strains has been associated with higher clinical burden and mortality rates. We review the current epidemiology, diagnostic, and therapeutic strategies of this clinical entity, with a special focus on patients with hematologic malignancies.

Recent Findings

There is an increase of azole resistance in Aspergillus spp. worldwide, probably due to environmental pressure and the increase of long-term azole prophylaxis and treatment in immunocompromised patients (e.g., in hematopoietic stem cell transplant recipients). The therapeutic approaches are challenging, due to multidrug-resistant strains, drug interactions, side effects, and patient-related conditions.

Summary

Rapid recognition of resistant Aspergillus spp. strains is fundamental to initiate an appropriate antifungal regimen, above all for allogeneic hematopoietic cell transplantation recipients. Clearly, more studies are needed in order to better understand the resistance mechanisms and optimize the diagnostic methods to identify Aspergillus spp. resistance to the existing antifungal agents/classes. More data on the susceptibility profile of Aspergillus spp. against the new classes of antifungal agents may allow for better treatment options and improved clinical outcomes in the coming years. In the meantime, continuous surveillance studies to monitor the prevalence of environmental and patient prevalence of azole resistance among Aspergillus spp. is absolutely crucial.

In vitro and in vivo evaluation of antifungal combinations against azole-resistant Aspergillus fumigatus isolates

Azole resistance in Aspergillus fumigatus (Af) has become a widespread threat and a major concern for optimal management of patients with invasive aspergillosis (IA). Combination of echinocandins with azoles is an attractive alternative option for the treatment of IA due to azole-resistant Af strains. The aim of this study was to evaluate the in vitro and in vivo combination of caspofungin (CAS) with either voriconazole (VRZ) or posaconazole (PSZ). In vitro interactions were assessed by two methods, and an animal model of IA in Galleria mellonella was used for in vivo evaluation. Assessment of efficacy was based on larvae mortality. Groups of 10 larvae were infected by 3 clinical strains of Af (azole susceptible, AfS; PSZ resistant, AfR1; VRZ and PSZ resistant strain, AfR2). In vitro, combination of CAS and azoles was indifferent against AfS, and AfR2, and a synergy was found for AfR1. When compared to VRZ monotherapy, the combination of VRZ at 4 µg/larva with CAS at 4 µg/larva improved survival of AfR2-infected larvae (p=0.0066). Combination of PSZ at 4µg/larva with CAS at 4 µg/larva improved survival of AfR1-infected larvae compared to CAS (p=0.0002) and PSZ (0.0024) monotherapy. Antagonism was never observed. In conclusion, the combination of caspofungin with azoles is a promising alternative for the treatment of azole resistant strains of Af.

Bioluminescence Imaging, a Powerful Tool to Assess Fungal Burden in Live Mouse Models of Infection

Aspergillus fumigatus and Cryptococcus neoformans species infections are two of the most common life-threatening fungal infections in the immunocompromised population. Acute invasive pulmonary aspergillosis (IPA) and meningeal cryptococcosis are the most severe forms affecting patients with elevated associated mortality rates despite current treatments. As many unanswered questions remain concerning these fungal infections, additional research is greatly needed not only in clinical scenarios but also under controlled preclinical experimental settings to increase our understanding concerning their virulence, host-pathogen interactions, infection development, and treatments. Preclinical animal models are powerful tools to gain more insight into some of these needs. However, assessment of disease severity and fungal burden in mouse models of infection are often limited to less sensitive, single-time, invasive, and variability-prone techniques such as colony-forming unit counting. These issues can be overcome by in vivo bioluminescence imaging (BLI). BLI is a noninvasive tool that provides longitudinal dynamic visual and quantitative information on the fungal burden from the onset of infection and potential dissemination to different organs throughout the development of disease in individual animals. Hereby, we describe an entire experimental pipeline from mouse infection to BLI acquisition and quantification, readily available to researchers to provide a noninvasive, longitudinal readout of fungal burden and dissemination throughout the course of infection development, which can be applied for preclinical studies into pathophysiology and treatment of IPA and cryptococcosis in vivo.

Liposomal amphotericin B-the present

Most invasive fungal infections are opportunistic in nature but the epidemiology is constantly changing, with new risk groups being identified. Neutropenia is a classical risk factor for fungal infections, while critically ill patients in the ICU are now increasingly at risk of yeast and mould infections. Factors to be considered when choosing antifungal treatment include the emergence of rarer fungal pathogens, the risk of resistance to azoles and echinocandins and the possibility of drug-drug interactions. Liposomal amphotericin B has retained its place in the therapeutic armamentarium based on its clinical profile: a broad spectrum of antifungal activity with a low risk of resistance, predictable pharmacokinetics with a rapid accumulation at the infection site (including biofilms), a low potential for drug-drug interactions and a low risk of acute and chronic treatment-limiting toxicities versus other formulations of amphotericin B. It is a suitable choice for the first-line empirical or pre-emptive treatment of suspected fungal infections in neutropenic haematology patients and is an excellent alternative for patients with documented fungal disease who can no longer tolerate or continue their first-line azole or echinocandin therapy, both in the haematology setting and in the ICU. Moreover, it is the first-line drug of choice for the treatment of invasive mucormycosis. Finally, liposomal amphotericin B is one of the few antifungal agents approved for use in children of all ages over 1 month and is included in paediatric-specific guidelines for the management of fungal disease.

Invasive Aspergillosis in the Intensive Care Unit

Invasive pulmonary aspergillosis (IPA) is a serious condition resulting in significant mortality and morbidity among patients in intensive care units (ICUs). There is a growing number of at-risk patients for this condition with the increasing use of immunosuppressive therapies. The diagnosis of IPA can be difficult in ICUs, and relies on integration of clinical, radiological, and microbiological features. In this review, we discuss patient populations at risk for IPA, as well as the diagnostic criteria employed. We review the fungal biomarkers used, as well as the challenges in distinguishing colonization with Aspergillus from invasive disease. We also address the growing concern of multidrug-resistant Aspergillosis and review the new and novel therapeutics which are in development to combat this.

In vitro activity of olorofim against Aspergillus fumigatus sensu lato clinical isolates: activity is retained against isolates showing resistance to azoles and/or amphotericin B

OBJECTIVES

New antifungal drugs, such as olorofim, may overcome the problem of resistance in Aspergillus fumigatus. We here report the activity of olorofim against a set of A. fumigatus sensu lato recently collected in Spain.

METHODS

A total of 332 A. fumigatus sensu lato clinical isolates collected in a multicentre study conducted in Spain in 2019 and comprising susceptible and resistant isolates to azoles and/or amphotericin B were tested. Isolates distributed among the following species: A. fumigatus sensu stricto (n = 312), Aspergillus lentulus (n = 6), Aspergillus fumigatiaffinis (n = 5), Neosartorya tsurutae (n = 3), Neosartorya udagawae (n = 3), Aspergillus novofumigatus (n = 2), and Aspergillus thermomutatus (n = 1). Azole resistance was found in 44 A. fumigatus sensu stricto isolates that harboured the following cyp51A gene substitutions: TR₃₄-L98H (n = 24), G54 (n = 5), TR₄₆/Y121F/T289A (n = 1), other mutations (n = 4), and gene wild type (n = 10). Isolates were tested for antifungal susceptibility to olorofim using European Committee on Antimicrobial Susceptibility Testing (EUCAST) E.Def. 9.4 methodology.

RESULTS

Olorofim minimum inhibitory concentrations against A. fumigatus sensu stricto isolates ranged from 0.008 to 0.125 mg/L and in vitro activity of the drug was not impacted by the presence of azole/amphotericin B resistance. Azole resistance and amphotericin B resistance was found in 18 and 13 cryptic species isolates, respectively. Olorofim showed high in vitro activity against cryptic species isolates and minimum inhibitory concentrations ranged from 0.004 to 0.016 mg/L, regardless of the presence of resistance to other drugs.

DISCUSSION

Olorofim showed in vitro activity against both A. fumigatus sensu stricto and cryptic species clinical isolates and was active against isolates showing resistance to azoles and/or amphotericin B.

Clinical utility of antifungal susceptibility testing

Invasive fungal diseases cause significant morbidity and mortality, in particular affecting immunocompromised patients. Resistant organisms are of increasing importance, yet there are many notable differences in the ability to both perform and interpret antifungal susceptibility testing compared with bacteria. In this review, we will highlight the strengths and limitations of resistance data of pathogenic yeasts and moulds that may be used to guide treatment and predict clinical outcomes.

Species Distribution and Antifungal Susceptibilities of Aspergillus Section Fumigati Isolates in Clinical Samples from the United States

Aspergillus species are capable of causing both invasive disease and chronic infections in immunocompromised patients or those with preexisting lung conditions. Aspergillus fumigatus is the most commonly cultured species, and there is increasing concern regarding resistance to the azoles, which are the mainstays of antifungal therapy against aspergillosis. We evaluated the species distribution and susceptibility profiles of isolates within Aspergillus section Fumigati in the United States over a 52-month period.

Longitudinal multimodal imaging-compatible mouse model of triazole-sensitive and -resistant invasive pulmonary aspergillosis

Invasive pulmonary aspergillosis (IPA) caused by the mold Aspergillus fumigatus is one of the most important life-threatening infections in immunocompromised patients. The alarming increase of isolates resistant to the first-line recommended antifungal therapy urges more insights into triazole-resistant A. fumigatus infections. In this study, we systematically optimized a longitudinal multimodal imaging-compatible neutropenic mouse model of IPA. Reproducible rates of pulmonary infection were achieved through immunosuppression (sustained neutropenia) with 150 mg/kg cyclophosphamide at day −4, −1 and 2, and an orotracheal inoculation route in both sexes. Furthermore, increased sensitivity of in vivo bioluminescence imaging for fungal burden detection, as early as the day after infection, was achieved by optimizing luciferin dosing and through engineering isogenic red-shifted bioluminescent A. fumigatus strains, one wild type and two triazole-resistant mutants. We successfully tested appropriate and inappropriate antifungal treatment scenarios in vivo with our optimized multimodal imaging strategy, according to the in vitro susceptibility of our luminescent fungal strains. Therefore, we provide novel essential mouse models with sensitive imaging tools for investigating IPA development and therapy in triazole-susceptible and triazole-resistant scenarios.

Summary: A novel reproducible longitudinal multimodal imaging-compatible neutropenic mouse model of invasive pulmonary aspergillosis provides increased early fungal detection through novel red-shifted luciferase-expressing triazole-susceptible and -resistant Aspergillus fumigatus strains, and boosted bioluminescence.

Azole Resistance in Aspergillus fumigatus. The first 2-year's Data from the Danish National Surveillance Study, 2018-2020

BACKGROUND

Azole resistance complicates treatment of patients with invasive aspergillosis with an increased mortality. Azole resistance in Aspergillus fumigatus is a growing problem and associated with human and environmental azole use. Denmark has a considerable and highly efficient agricultural sector. Following reports on environmental azole resistance in A. fumigatus from Danish patients the ministry of health requested a prospective national surveillance of azole resistant A. fumigatus and particularly that of environmental origin.

OBJECTIVES

To present the data from the first two years of the surveillance programme.

METHODS

Unique isolates regarded as clinically relevant and any A. fumigatus isolated on a preferred weekday (background samples) were included. EUCAST susceptibility testing was performed and azole-resistant isolates underwent cyp51A gene sequencing.

RESULTS

The azole resistance prevalence was 6.1% (66/1083) at patient level. The TR₃₄ /L98H prevalence was 3.6% (39/1083) and included the variants TR₃₄ /L98H, TR₃₄ ³ /L98H and TR₃₄ /L98H/S297T/F495I. Resistance caused by other Cyp51A variants accounted for 1.3% (14/1083) and included G54R, P216S, F219L, G54W, M220I, M220K, M220R, G432S, G448S and Y121F alterations. Non-Cyp51A mediated resistance accounted for 1.2% (13/1083). Proportionally, TR₃₄ /L98H, other Cyp51A variants and non-Cyp51A mediated resistance accounted for 59.1% (39/66), 21.2% (14/66) and 19.7% (13/66), respectively, of all resistance. Azole resistance was detected in all five Regions in Denmark, and TR₃₄ /L98H specifically, in four of five regions during the surveillance period.

CONCLUSION

The azole resistance prevalence does not lead to a change in the initial treatment of aspergillosis at this point, but causes concern and leads to therapeutic challenges in the affected patients.

OUP accepted manuscript

The increasing incidence and changing epidemiology of invasive fungal infections continue to present many challenges to their effective management. The repertoire of antifungal drugs available for treatment is still limited although there are new antifungals on the horizon. Successful treatment of invasive mycoses is dependent on a mix of pathogen-, host- and antifungal drug-related factors. Laboratories need to be adept at detection of fungal pathogens in clinical samples in order to effectively guide treatment by identifying isolates with acquired drug resistance. While there are international guidelines on how to conduct in vitro antifungal susceptibility testing, these are not performed as widely as for bacterial pathogens. Furthermore, fungi generally are recovered in cultures more slowly than bacteria, and often cannot be cultured in the laboratory. Therefore, non-culture-based methods, including molecular tests, to detect fungi in clinical specimens are increasingly important in patient management and are becoming more reliable as technology improves. Molecular methods can also be used for detection of target gene mutations or other mechanisms that predict antifungal drug resistance. This review addresses acquired antifungal drug resistance in the principal human fungal pathogens and describes known resistance mechanisms and what in-house and commercial tools are available for their detection. It is emphasized that this approach should be complementary to culture-based susceptibility testing, given the range of mutations, resistance mechanisms and target genes that may be present in clinical isolates, but may not be included in current molecular assays.

Discovery of Octahydroisoindolone as a Scaffold for the Selective Inhibition of Chitinase B1 from Aspergillus fumigatus: In Silico Drug Design Studies

Chitinases represent an alternative therapeutic target for opportunistic invasive mycosis since they are necessary for fungal cell wall remodeling. This study presents the design of new chitinase inhibitors from a known hydrolysis intermediate. Firstly, a bioinformatic analysis of Aspergillus fumigatus chitinase B1 (AfChiB1) and chitotriosidase (CHIT1) by length and conservation was done to obtain consensus sequences, and molecular homology models of fungi and human chitinases were built to determine their structural differences. We explored the octahydroisoindolone scaffold as a potential new antifungal series by means of its structural and electronic features. Therefore, we evaluated several synthesis-safe octahydroisoindolone derivatives by molecular docking and evaluated their AfChiB1 interaction profile. Additionally, compounds with the best interaction profile (1–5) were docked within the CHIT1 catalytic site to evaluate their selectivity over AfChiB1. Furthermore, we considered the interaction energy (MolDock score) and a lipophilic parameter (aLogP) for the selection of the best candidates. Based on these descriptors, we constructed a mathematical model for the IC₅₀ prediction of our candidates (60–200 μM), using experimental known inhibitors of AfChiB1. As a final step, ADME characteristics were obtained for all the candidates, showing that 5 is our best designed hit, which possesses the best pharmacodynamic and pharmacokinetic character.

Aspergillosis: Emerging risk groups in critically ill patients

Information on invasive aspergillosis (IA) and other invasive filamentous fungal infections is limited in non-neutropenic patients admitted to the intensive care unit (ICU) and presenting with no classic IA risk factors. This review is based on the critical appraisal of relevant literature, on the authors' own experience and on discussions that took place at a consensus conference. It aims to review risk factors favoring aspergillosis in ICU patients, with a special emphasis on often overlooked or neglected conditions. In the ICU patients, corticosteroid use to treat underlying conditions such as chronic obstructive pulmonary disease (COPD), sepsis, or severe COVID-19, represents a cardinal risk factor for IA. Important additional host risk factors are COPD, decompensated cirrhosis, liver failure, and severe viral pneumonia (influenza, COVID-19). Clinical observations indicate that patients admitted to the ICU because of sepsis or acute respiratory distress syndrome are more likely to develop probable or proven IA, suggesting that sepsis could also be a possible direct risk factor for IA, as could small molecule inhibitors used in oncology. There are no recommendations for prophylaxis in ICU patients; posaconazole mold-active primary prophylaxis is used in some centers according to guidelines for other patient populations and IA treatment in critically ill patients is basically the same as in other patient populations. A combined evaluation of clinical signs and imaging, classical biomarkers such as the GM assay, and fungal cultures examination, remain the best option to assess response to treatment.

LAY SUMMARY

The use of corticosteroids and the presence of co-morbidities such as chronic obstructive pulmonary disease, acute or chronic advanced liver disease, or severe viral pneumonia caused by influenza or Covid-19, may increase the risk of invasive aspergillosis in intensive care unit patients.

Stable prevalence of triazole-resistance in Aspergillus fumigatus complex clinical isolates in a Belgian tertiary care center from 2016 to 2020

BACKGROUND

Prevalence reports of triazole-resistance in Aspergillus fumigatus differ between countries and centers and may likewise vary over time. Continuous local surveillance programs to establish the evolving epidemiology of triazole-resistance in A. fumigatus are crucial to guide therapeutic recommendations. Here, we determined the prevalence of triazole-resistance in A. fumigatus complex culture-positive patients at the tertiary care center University Hospitals Leuven in Belgium in clinical isolates from 2016 to 2020.

METHODS

All A. fumigatus complex isolates cultured from UZ Leuven patients between 2016 and 2020 were screened for triazole-resistance. Confirmation of resistance to voriconazole, posaconazole and itraconazole was performed with the European Committee for Antimicrobial Susceptibility Testing (EUCAST) broth microdilution method. Mutations in the cyp51A gene in triazole-resistant isolates were determined by sequencing. Patients were classified as susceptible or resistant cases based on their isolate's susceptibility phenotype.

RESULTS

We screened 2494 A. fumigatus complex isolates from 1600 patients (320 ± 38 [SD] patients per year). The prevalence of triazole-resistance in patients was 8.3% (28/337), 6.7% (26/386), 7.0% (21/301), 7.1% (21/294) and 7.4% (21/282) in 2016, 2017, 2018, 2019 and 2020 respectively, with an overall triazole-resistance prevalence of 7.1% (85/1192; 95% CI 6.6-7.7%). The TR₃₄/L98H mutation was the most prevalent (83.0%, 78/94) with most isolates displaying resistance to all triazole antifungals tested (94.8%, 74/78).

CONCLUSION

The prevalence of triazole-resistance in A. fumigatus has remained stable from 2016 to 2020 in our center ranging between 6.7 and 8.3%, with an overall five-year prevalence of 7.1%. The environmentally associated cyp51A gene mutations were most prevalent amongst triazole-resistant isolates and conferred resistance to all antifungals tested in 73% of the isolates.

When to change treatment of acute invasive aspergillosis: an expert viewpoint

Invasive aspergillosis (IA) is an acute infection affecting patients who are immunocompromised, as a result of receiving chemotherapy for malignancy, or immunosuppressant agents for transplantation or autoimmune disease. Whilst criteria exist to define the probability of infection for clinical trials, there is little evidence in the literature or clinical guidelines on when to change antifungal treatment in patients who are receiving prophylaxis or treatment for IA. To try and address this significant gap, an advisory board of experts was convened to develop criteria for the management of IA for use in designing clinical trials, which could also be used in clinical practice. For primary treatment failure, a change in antifungal therapy should be made: (i) when mycological susceptibility testing identifies an organism from a confirmed site of infection, which is resistant to the antifungal given for primary therapy, or a resistance mutation is identified by molecular testing; (ii) at, or after, 8 days of primary antifungal treatment if there is increasing serum galactomannan, or galactomannan positivity in serum, or bronchoalveolar lavage fluid when the antigen was previously undetectable, or there is sudden clinical deterioration, or a new clearly distinct site of infection is detected; and (iii) at, or after, 15 days of primary antifungal treatment if the patient is clinically stable but with ≥2 serum galactomannan measurements persistently elevated compared with baseline or increasing, or if the original lesions on CT or other imaging, show progression by >25% in size in the context of no apparent change in immune status.

Molecular epidemiology of aspergillosis in Magellanic penguins and susceptibility patterns of clinical isolates

Aspergillus section Fumigati is reported in up to 99% of aspergillosis cases in penguins. So far, no data regarding molecular epidemiology and azole resistance are available for A. fumigatus isolates collected from Magellanic penguins. The aim of this work was to perform molecular identification of Aspergillus section Fumigati at species level, to genotype those isolates using microsatellite markers, to evaluate the in vitro susceptibility patterns of A. fumigatus sensu stricto, and to characterize the cyp51A gene in clinical A. fumigatus strains isolated from Magellanic penguins with proven aspergillosis. All 34 isolates included in the study were identified as A. fumigatus sensu stricto. Analyzing the genetic diversity of the isolates of A. fumigatus sensu stricto, we identified two possible outbreaks in the rehabilitation center and we also observed the maintenance of clonal strains through the years. One A. fumigatus sensu stricto isolate was resistant to posaconazole, but the mutations found in the cyp51A gene of this isolate have not been described as conferring phenotypic resistance, suggesting that other mechanisms of resistance could be involved in the resistance of this isolate. With this study we were able to understand the molecular diversity of Aspergillus fumigatus isolates collected from Magellanic penguins, to characterize them and to associate them with the described global population of Aspergillus fumigatus.

Combined high dose caspofungin and liposomal amphotericin B for the treatment of azole-resistant cerebral aspergillosis

The prevalence of azole-resistant aspergillosis is increasing and represents a public health issue in some countries, with an excess mortality of 25% (1).….

Comparative activity of posaconazole and systemic azole agents against clinical isolates of filamentous fungi from a global surveillance programme

Objectives

The activity of mould-active azoles was evaluated against 397 filamentous fungi causing invasive mould infections (IMI) worldwide. In addition, a tentative posaconazole epidemiological cut-off value (ECV) against Aspergillus fumigatus was investigated.

Methods

Isolates were susceptibility tested by the CLSI reference broth microdilution methods. Species identification was confirmed by MALDI-TOF and/or sequencing analysis.

Results

Aspergillus spp. (81.9%) remained the most common organism causing IMI worldwide; approximately two-thirds of Aspergillus spp. recovered were A. fumigatus. In general, more than 90% of 220 A. fumigatus isolates were wild type (WT) to all mould-active azoles, except itraconazole (84.5% WT). The voriconazole non-susceptible (NS) A. fumigatus rate was 7.7% overall and was higher in Europe (12.9%) than in the other regions (0%–5.8%). Posaconazole (MIC₅₀/MIC₉₀, 0.25/0.5 mg/L) showed similar or slightly higher activity than voriconazole (MIC₅₀/MIC₉₀, 0.5/0.5 mg/L) and isavuconazole (MIC₅₀/MIC₉₀, 0.5/1 mg/L) against A. fumigatus. The mould-active azoles displayed similar activity against non-fumigatus Aspergillus (WT rates >93%), but differences were observed among the main species/sections. Posaconazole, voriconazole, and isavuconazole inhibited at their respective ECVs 100%, 97.0%, and 100% of A. section Nigri; 100%, 100%, and 93.8% of A. section Terrei; and 97.3%, 100%, and 100% of A. section Flavi isolates. Posaconazole displayed potency greater than or equal to the other azoles against the Mucorales group and Scedosporium spp.

Conclusions

Posaconazole and other mould-active azoles showed good activity against Aspergillus spp. causing IMI, but clinicians should be aware of regional rates of voriconazole-NS A. fumigatus.

Azole resistance in Aspergillus species: promising therapeutic options

INTRODUCTION

Azoles are the first-line antifungal agents used for the treatment of Aspergillus infection. There is an increasing concern for azole resistance all over the world mainly from agricultural fungicide use. Choosing safe and effective antifungal regimens has become a challenge.

AREAS COVERED

Here, the authors review the epidemiology, mechanisms, and detection of azole resistance along with management options for azole-resistant Aspergillus infection, including new antifungal agents under development.

EXPERT OPINION

Routine global epidemiological surveillance is required to understand azole resistance prevalence. Azole-resistant Aspergillus infections are associated with high mortality. No good therapeutic options are currently available. High index of suspicion of resistance is required if a patient is not responding to 4-7 days of azole therapy, particularly in the areas of resistance. Susceptibility testing for Aspergillus is not routinely available in many parts of the world, which makes it difficult to diagnose azole resistance in Aspergillus infection. There are several new antifungal classes with novel mechanisms of action; clinical trials are ongoing.

Antifungals in Clinical Use and the Pipeline

Over the past 15 years, there has been an increase in the development and utilization of newer antifungal agents. The ideal antifungal, however, in regard to spectrum of activity, pharmacokinetic/pharmacodynamic properties, development of resistance, safety, and drug interaction profile remains elusive. This article reviews pharmacologic aspects of Food and Drug Administration-approved polyenes, flucytosine, azoles, and echinocandins as well as promising pipeline antifungal agents. Unique properties of these newer agents are highlighted. The clinical role of established and investigational antifungal agents as treatment and/or prevention of invasive fungal infections is discussed.

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.

Triazole-Resistance in Environmental Aspergillus fumigatus in Latin American and African Countries

Triazole-resistance has been reported increasingly in Aspergillus fumigatus. An international expert team proposed to avoid triazole monotherapy for the initial treatment of invasive aspergillosis in regions with >10% environmental-resistance, but this prevalence is largely unknown for most American and African countries. Here, we screened 584 environmental samples (soil) from urban and rural locations in Mexico, Paraguay, and Peru in Latin America and Benin and Nigeria in Africa for triazole-resistant A. fumigatus. Samples were screened using triazole-containing agars and confirmed as triazole-resistant by the European Committee on Antimicrobial Susceptibility Testing (EUCAST) broth dilution reference method. Isolates were further characterized by cyp51A sequencing and short-tandem repeat typing. Fungicide presence in samples was likewise determined. Among A. fumigatus positive samples, triazole-resistance was detected in 6.9% (7/102) of samples in Mexico, 8.3% (3/36) in Paraguay, 9.8% (6/61) in Peru, 2.2% (1/46) in Nigeria, and none in Benin. Cyp51A gene mutations were present in most of the triazole-resistant isolates (88%; 15/17). The environmentally-associated mutations TR₃₄/L98H and TR₄₆/Y121F/T289A were prevalent in Mexico and Peru, and isolates harboring these mutations were closely related. For the first time, triazole-resistant A. fumigatus was found in environmental samples in Mexico, Paraguay, Peru, and Nigeria with a prevalence of 7-10% in the Latin American countries. Our findings emphasize the need to establish triazole-resistance surveillance programs in these countries.

Invasive pulmonary aspergillosis after liver transplantation: lessons from successfully treated cases and review of the literature

PURPOSE

Invasive pulmonary aspergillosis (IPA) after liver transplantation (LT) is most often fatal. We analyzed the outcomes of IPA in a single center.

METHODS

We reviewed, retrospectively, the medical records of recipients of living donor LT (LDLT) or deceased donor LT (DDLT) performed between 1995 and 2019 at our institute. We analyzed the incidence of IPA and assessed the treatment courses of patients treated successfully and those not treatment successfully.

RESULTS

Among 326 recipients, IPA was diagnosed in 6 (1.8%). The incidence of IPA was significantly higher in patients with acute liver failure (ALF, 9.8%) than in those without ALF (0.4%), after DDLT (8.8%) than after LDLT (1.0%), and in recipients who received preoperative steroid pulse therapy (16.0%) than in those who did not (0.7%). Complete cure of IPA was achieved in the most recent three patients, by administering voriconazole immediately after the diagnosis of IPA and performing lung resection, while the IPA lesion was single and localized.

CONCLUSIONS

Patients with risk factors for IPA must be monitored closely. Our three successfully treated cases demonstrate that initiating immediate voriconazole treatment and making a calculated decision about lung resection can contribute to a favorable outcome.

Prevalence of Azole-Resistant Aspergillus fumigatus is Highly Associated with Azole Fungicide Residues in the Fields

Triazole resistance in Aspergillus fumigatus is a growing public health concern. In addition to its emergence in the therapy of invasive aspergillosis by triazole medicines, it has been frequently detected in agricultural fields all over the world. Here, we explore the potential link between residues of azole fungicides with similar chemical structure to triazole medicines in soil and the emergence of resistant A. fumigatus (RAF) through 855 500 km² monitoring survey in Eastern China covering 6 provinces. In total, 67.3%, 15.2%, 12.3%, 2.9%, 1.5%, 0.4%, and 0.3% of the soil samples contained these five fungicides (tebuconazole, difenoconazole, propiconazole, hexaconazole, and prochloraz) of 0-100, 100-200, 200-400, 400-600, 600-800, 800-1000, and >1000 ng/g, respectively. The fractions of samples containing RAF isolates were 2.4%, 5.2%, 6.4%, 7.7%, 7.4%, 14.3%, and 20.0% of the samples with total azole fungicide residues of 0-100, 100-200, 200-400, 400-600, 600-800, 800-1000, and >1000 ng/g, respectively. We find that the prevalence of RAFs is positively (P < 0.0001) correlated with residual levels of azole fungicides in soils. Our results suggest that the use of azole fungicides in agriculture should be minimized and the intervals between treatments expanded to reduce the selective pressure toward the development of resistance in A. fumigatus in agricultural fields.

Dynamics of Aspergillus fumigatus in Azole Fungicide-Containing Plant Waste in the Netherlands (2016-2017)

The treatment of patients suffering from Aspergillus diseases is hampered due to infections with Aspergillus fumigatus that are already resistant to medical azoles. Previous work has suggested that A. fumigatus likely gains resistance through environmental azole exposure in so-called hot spots. Here, we investigated A. fumigatus resistance dynamics over time at three sites at which farmers used azole fungicides for crop protection. Over 16 months, 114 samples were taken from stockpiles of decaying plant waste. A. fumigatus and azole fungicide residues were ubiquitously present in the plant waste. On average, 10⁵ A. fumigatus CFU/g was recovered, of which roughly half were itraconazole and tebuconazole resistant. Similar tandem repeat-mediated resistance mechanisms were found in colonies cultured from plant waste as reported in clinical azole-resistant isolates. Our results show a consistent high burden of azole-resistant A. fumigatus in azole-containing plant waste and underscores the need to further investigate resistance-reducing interventions and transmission routes.IMPORTANCE Aspergillus fumigatus is consistently present independently on season at a high abundance in plant waste material throughout the sampling period. Our study confirmed that long-term storage sites of azole-containing decaying plant material can indeed be considered hot spots, which can sustain resistance development and maintenance in A. fumigatus Roughly half of individual isolates were azole resistant and carried genetic mutations that are highly similar to those found in patients with azole-resistant invasive aspergillosis. Our work suggests that environmental sources of azole resistance in A. fumigatus may be important, underscoring the need for further studies on environment-to-patient transmission routes.

Pharmacokinetics and Pharmacodynamics of Posaconazole

Posaconazole is typically used for preventing invasive yeast and mold infections such as invasive aspergillosis in high-risk immunocompromised patients. The oral suspension was the first released formulation and many pharmacokinetic and pharmacodynamic studies of this formulation have been published. Erratic absorption profiles associated with this formulation were widely reported. Posaconazole exposure was found to be significantly influenced by food and many gastrointestinal conditions, including pH and motility. As a result, low posaconazole plasma concentrations were obtained in large groups of patients. These issues of erratic absorption urged the development of the subsequently marketed delayed-release tablet, which proved to be associated with higher and more stable exposure profiles. Shortly thereafter, an intravenous formulation was released for patients who are not able to take oral formulations. Both new formulations require a loading dose on day 1 to achieve high posaconazole concentrations more quickly, which was not possible with the oral suspension. So far, there appears to be no evidence of increased toxicity correlated to the higher posaconazole exposure achieved with the regimen for these formulations. The higher systemic availability of posaconazole for the delayed-release tablet and intravenous formulation have resulted in these two formulations being preferable for both prophylaxis and treatment of invasive fungal disease. This review aimed to integrate the current knowledge on posaconazole pharmacokinetics, pharmacodynamics, major toxicity, existing resistance, clinical experience in special populations, and new therapeutic strategies in order to get a clear understanding of the clinical use of this drug.

Sterol 14α-Demethylase Ligand-Binding Pocket-Mediated Acquired and Intrinsic Azole Resistance in Fungal Pathogens

The fungal cytochrome P450 enzyme sterol 14α-demethylase (SDM) is a key enzyme in the ergosterol biosynthesis pathway. The binding of azoles to the active site of SDM results in a depletion of ergosterol, the accumulation of toxic intermediates and growth inhibition. The prevalence of azole-resistant strains and fungi is increasing in both agriculture and medicine. This can lead to major yield loss during food production and therapeutic failure in medical settings. Diverse mechanisms are responsible for azole resistance. They include amino acid (AA) substitutions in SDM and overexpression of SDM and/or efflux pumps. This review considers AA affecting the ligand-binding pocket of SDMs with a primary focus on substitutions that affect interactions between the active site and the substrate and inhibitory ligands. Some of these interactions are particularly important for the binding of short-tailed azoles (e.g., voriconazole). We highlight the occurrence throughout the fungal kingdom of some key AA substitutions. Elucidation of the role of these AAs and their substitutions may assist drug design in overcoming some common forms of innate and acquired azole resistance.

A Multidisciplinary Approach to Fungal Infections: One-Year Experiences of a Center of Expertise in Mycology

Invasive fungal diseases (IFDs) often represent complicated infections in complex patient populations. The Center of Expertise in Mycology Radboudumc/CWZ (EMRC) organizes a biweekly multidisciplinary mycology meeting to discuss patients with severe fungal infections and to provide comprehensive advice regarding diagnosis and treatment. Here, we describe the patient population discussed at these meetings during a one-year period with regards to their past medical history, diagnosis, microbiological and other diagnostic test results and antifungal therapy. The majority of patients discussed were adults (83.1%), 62.5% of whom suffered from pulmonary infections or signs/symptoms, 10.9% from otorhinolaryngeal infections and/or oesophagitis, 9.4% from systemic infections and 9.4% from central nervous system infections. Among children, 53.8% had pulmonary infections or signs/symptoms, 23.1% systemic fungal infections and 23.1% other, miscellaneous fungal infections. 52.5% of adult patients with pulmonary infections/symptoms fulfilled diagnostic criteria for chronic pulmonary aspergillosis (CPA). Culture or polymerase chain reaction (PCR) demonstrated fungal pathogens in 81.8% of patients, most commonly Aspergillus. A multidisciplinary mycology meeting can be a useful addition to the care for patients with (I)FDs and can potentially aid in identifying healthcare and research needs regarding the field of fungal infections. The majority of patients discussed at the multidisciplinary meetings suffered from pulmonary infections, predominantly CPA.

Hmg1 Gene Mutation Prevalence in Triazole-Resistant Aspergillus fumigatus Clinical Isolates

Recently, mutations in the 3-hydroxy-3-methylglutaryl-coenzyme-A-reductase-encoding gene (hmg1), a gene involved in ergosterol production, were associated with triazole-resistance in Aspergillus fumigatus. In this study, we determined the prevalence and characteristics of hmg1 mutations in a collection of clinical triazole-resistant A. fumigatus isolates collected during 2001–2019 from two international mycology reference centers: the Belgian National Reference Center for Mycosis and the Center of Expertise in Mycology Radboudumc/CWZ. Clinical isolates with and without cyp51A gene mutations and randomly selected wild-type (WT) controls were included. Isolates were characterized by in vitro susceptibility testing, cyp51A and hmg1 sequencing, and short tandem repeat typing. Available clinical records were analyzed for previous triazole exposure. In 23 isolates (24%) of the 95 triazole-resistant A. fumigatus isolates, hmg1 gene mutations were observed; including 5/23 (22%) isolates without cyp51A gene mutations and 18/72 (25%) with cyp51A mutations. Four previously described hmg1 gene mutations (E105K, G307R/D, G466V, and S541G) and two novel mutations (W273S and L304P) were found; 4/23 (17%) in the sterol-sensing-domain region. No triazole-antifungal exposure was reported in 75% (9/12) of patients harboring an isolate with hmg1 gene mutations. Three of 39 WT isolates (8%) contained a hmg1 gene mutation; E105K (2-isolates) and S541G. Hmg1 gene mutations were predominantly found in A. fumigatus with cyp51A mutations with voriconazole MICs ≥ 8 mg/L.

Clonal Expansion of Environmental Triazole Resistant Aspergillus fumigatus in Iran

Azole-resistance in Aspergillus fumigatus is a worldwide medical concern complicating the management of aspergillosis (IA). Herein, we report the clonal spread of environmental triazole resistant A. fumigatus isolates in Iran. In this study, 63 A. fumigatus isolates were collected from 300 compost samples plated on Sabouraud dextrose agar supplemented with itraconazole (ITR) and voriconazole (VOR). Forty-four isolates had the TR34/L98H mutation and three isolates a TR46/Y121F/T289A resistance mechanism, while two isolates harbored a M172V substitution in cyp51A. Fourteen azole resistant isolates had no mutations in cyp51A. We found that 41 out of 44 A. fumigatus strains with the TR34/L98H mutation, isolated from compost in 13 different Iranian cities, shared the same allele across all nine examined microsatellite loci. Clonal expansion of triazole resistant A. fumigatus in this study emphasizes the importance of establishing antifungal resistance surveillance studies to monitor clinical Aspergillus isolates in Iran, as well as screening for azole resistance in environmental A. fumigatus isolates.

Aspergillus fumigatus and pan-azole resistance: who should be concerned?

PURPOSE OF REVIEW

Although clinical outcomes in the treatment of aspergillosis have markedly improved with the availability of newer triazoles, the development of resistance to these antifungals, especially in Aspergillus fumigatus, is a growing concern. The purpose of this review is to provide an update on azole resistance mechanisms and their epidemiology in A. fumigatus, the clinical implications of azole resistance, and to discuss future treatment options against azole-resistant aspergillosis.

RECENT FINDINGS

Resistance may develop through either patient or environmental azole exposure. Environmental exposure is the most prevalent means of resistance development, and these isolates can cause disease in various at-risk groups, which now include those with influenza, and potentially COVID-19. Although current treatment options are limited, newer therapies are in clinical development. These include agents with novel mechanisms of action which have in vitro and in vivo activity against azole-resistant A. fumigatus.

SUMMARY

Azole-resistant A. fumigatus is an emerging threat that hampers our ability to successfully treat patients with aspergillosis. Certain geographic regions and patient populations appear to be at increased risk for this pathogen. As new patient groups are increasingly recognized to be at increased risk for invasive aspergillosis, studies to define the epidemiology and management of azole-resistant A. fumigatus are critically needed. While treatment options are currently limited, new agents under clinical development may offer hope.

COVID-19 Associated Invasive Pulmonary Aspergillosis: Diagnostic and Therapeutic Challenges

Aspergillus co-infection in patients with severe coronavirus disease 2019 (COVID-19) pneumonia, leading to acute respiratory distress syndrome, has recently been reported. To date, 38 cases have been reported, with other cases most likely undiagnosed mainly due to a lack of clinical awareness and diagnostic screening. Importantly, there is currently no agreed case definition of COVID-19 associated invasive pulmonary aspergillosis (CAPA) that could aid in the early detection of this co-infection. Additionally, with the global emergence of triazole resistance, we emphasize the importance of antifungal susceptibility testing in order to ensure appropriate antifungal therapy. Herein is a review of 38 published CAPA cases, which highlights the diagnostic and therapeutic challenges posed by this novel fungal co-infection.

Emergence of azole resistant-Aspergillus fumigatus infections during STAT3-deficiency

Introduction. Signal transducer and activator of transcription 3 (STAT3) deficiency is a rare primary immunodeficiency associated with increased susceptibility to bacterial and fungal infections, notably pulmonary aspergillosis.Aim. We describe the emergence of azole-resistant Aspergillus fumigatus infections in STAT3-deficient patients.Methodology. During a retrospective study of 13 pulmonary aspergillosis cases in STAT3-deficient patients conducted in France, we identified patients infected with azole-resistant A. fumigatus isolates.Results. Two out of the 13 STAT3-deficient patients with aspergillosis had azole-resistant A. fumigatus infection, indicating an unexpectedly high prevalence of resistance. The first patient with STAT3 deficiency presented several flares of allergic bronchopulmonary aspergillosis-like episodes. He was chronically infected with two azole-resistant A. fumigatus isolates (TR₃₄/L98). Despite prolonged antifungal treatment, including caspofungin and amphotericin B, the patient was not able to clear the azole-resistant A. fumigatus. The second patient had chronic cavitary pulmonary aspergillosis (CCPA). The A. fumigatus isolate was initially azole susceptible but harboured three F46Y, M172V and E427K point mutations. Despite prolonged antifungal therapies, lesions worsened and the isolate became resistant to all azoles. Surgery and caspofungin treatments were then required to cure CCPA. Resistance was probably acquired from the environment (TR₃₄/L98) in the first case whereas resistance developed under antifungal treatments in the second case. These infections required long-term antifungal treatments and surgery.Conclusions. The emergence of azole-resistant A. fumigatus infections in STAT3-deficiency dramatically impacts both curative and prophylactic antifungal strategies. Physicians following patients with primary immune-deficiencies should be aware of this emerging problem as it complicates management of the patient.

How to interpret MICs of antifungal compounds according to the revised clinical breakpoints v. 10.0 European committee on antimicrobial susceptibility testing (EUCAST)

BACKGROUND

EUCAST has revised the definition of the susceptibility category I from 'Intermediate' to 'Susceptible, Increased exposure'. This implies that I can be used where the drug concentration at the site of infection is high, either because of dose escalation or through other means to ensure efficacy. Consequently, I is no longer used as a buffer zone to prevent technical factors from causing misclassifications and discrepancies in interpretations. Instead, an Area of Technical Uncertainty (ATU) has been introduced for MICs that cannot be categorized without additional information as a warning to the laboratory that decision on how to act has to be made. To implement these changes, the EUCAST-AFST (Subcommittee on Antifungal Susceptibility Testing) reviewed all, and revised some, clinical antifungal breakpoints.

OBJECTIVES

The aim was to present an overview of the current antifungal breakpoints and supporting evidence behind the changes.

SOURCES

This document is based on the ten recently updated EUCAST rationale documents, clinical breakpoint and breakpoint ECOFF documents.

CONTENT

The following breakpoints (in mg/L) have been revised or established for Candida species: micafungin against C. albicans (ATU = 0.03); amphotericin B (S ≤/> R = 1/1), fluconazole (S ≤/> R = 2/4), itraconazole (S ≤/> R = 0.06/0.06), posaconazole (S ≤/> R = 0.06/0.06) and voriconazole (S ≤/> R = 0.06/0.25) against C. dubliniensis; fluconazole against C. glabrata (S ≤/> R = 0.001/16); and anidulafungin (S ≤/> R = 4/4) and micafungin (S ≤/> R = 2/2) against C. parapsilosis. For Aspergillus, new or revised breakpoints include itraconazole (ATU = 2) and isavuconazole against A. flavus (S ≤/> R = 1/2, ATU = 2); amphotericin B (S ≤/> R = 1/1), isavuconazole (S ≤ /> R = 1/2, ATU = 2), itraconazole (S ≤/> R = 1/1, ATU = 2), posaconazole (ATU = 0.25) and voriconazole (S ≤/> R = 1/1, ATU = 2) against A. fumigatus; itraconazole (S ≤/> R = 1/1, ATU = 2) and voriconazole (S ≤/> R = 1/1, ATU = 2) against A. nidulans; amphotericin B against A. niger (S ≤/> R = 1/1); and itraconazole (S ≤/> R = 1/1, ATU = 2) and posaconazole (ATU = 0.25) against A. terreus.

IMPLICATIONS

EUCAST-AFST has released ten new documents summarizing existing and new breakpoints and MIC ranges for control strains. A failure to adopt the breakpoint changes may lead to misclassifications and suboptimal or inappropriate therapy of patients with fungal infections.

Burden of serious fungal infections in the Netherlands

Background

Fungal diseases have an ever‐increasing global disease burden, although regional estimates for specific fungal diseases are often unavailable or dispersed.

Objectives

Here, we report the current annual burden of life‐threatening and debilitating fungal diseases in the Netherlands.

Methods

The most recent available epidemiological data, reported incidence and prevalence of fungal diseases were used for calculations.

Results

Overall, we estimate that the annual burden of serious invasive fungal infections in the Netherlands totals 3 185 patients, including extrapulmonary or disseminated cryptococcosis (n = 9), pneumocystis pneumonia (n = 740), invasive aspergillosis (n = 1 283), chronic pulmonary aspergillosis (n = 257), invasive Candida infections (n = 684), mucormycosis (n = 15) and Fusarium keratitis (n = 8). Adding the prevalence of recurrent vulvo‐vaginal candidiasis (n = 220 043), allergic bronchopulmonary aspergillosis (n = 13 568) and severe asthma with fungal sensitisation (n = 17 695), the total debilitating burden of fungal disease in the Netherlands is 254 491 patients yearly, approximately 1.5% of the country's population.

Conclusion

We estimated the annual burden of serious fungal infections in the Netherlands at 1.5% of the population based on previously reported modelling of fungal rates for specific populations at risk. With emerging new risk groups and increasing reports on antifungal resistance, surveillance programmes are warranted to obtain more accurate estimates of fungal disease epidemiology and associated morbidity and mortality.

First azole-resistant Aspergillus fumigatus isolates with the environmental TR46 /Y121F/T289A mutation in Iran

Background

Azole resistance in Aspergillus fumigatus is an emerging problem and reported from all continents. As triazole antifungals are the mainstay of therapy in the management of invasive aspergillosis, azole‐resistant A fumigatus has become a major medical concern and with complicated clinical management.

Objective

Screening of environmental presence of azole‐resistant A fumigatus in Iran.

Methods

Compost from Northern Iran, collected between 2017 and 2018, was screened for the presence of azole‐resistant A fumigatus with azole‐containing agar. Phenotypic MICs were obtained from selected, molecularly confirmed isolates. cyp51A gene sequencing and genotyping of azole‐resistant isolates were done.

Results

Among 300 compost samples, three A fumigatus isolates had high voriconazole MICs (≥16 mg/L) and harboured the TR₄₆/Y121F/T289A mutation in the cyp51A gene. Microsatellite typing of these isolates showed that two strains had the same allele across all nine examined microsatellite loci and were genotypically related to Indian azole‐resistant strains. The other isolate had a different genotype.

Conclusion

This is the first report of A fumigatus with TR₄₆/Y121F/T289A mutation from the region. Monitoring and surveillance of antifungal susceptibility of clinical A fumigatus is warranted in Iran and elsewhere in the region.

Invasive pulmonary aspergillosis treatment duration in haematology patients in Europe: An EFISG, IDWP-EBMT, EORTC-IDG and SEIFEM survey

Invasive pulmonary aspergillosis (IPA) optimal duration of antifungal treatment is not known. In a joint effort, four international scientific societies/groups performed a survey to capture current practices in European haematology centres regarding management of IPA. We conducted a cross-sectional internet-based questionnaire survey in 2017 to assess practices in sixteen European countries concerning IPA management in haematology patients including tools to evaluate treatment response, duration and discontinuation. The following four groups/societies were involved in the project: European Society of Clinical Microbiology and Infectious Diseases (ESCMID) Fungal Infection Study Group (EFISG), Infectious Diseases Working Party-European Society for Blood and Bone Marrow Transplantation (IDWP-EBMT), European Organisation for Research and Treatment-Infectious Disease group (EORTC-IDG) and Sorveglianza Epidemiologica Infezioni nelle Emopatie (SEIFEM). A total of 112 physicians from 14/16 countries answered the survey. Galactomannan antigen was available in serum and bronchoalveolar lavage in most centres (106/112 [95%] and 97/112 [87%], respectively), quantitative Aspergillus PCR in 27/112 (24%) centres, β-D-glucan in 24/112 (21%) and positron emission tomography in 50/112 (45%). Treatment duration differed between haematological malignancies, with a median duration of 6 weeks [IQR 3-12] for patients with AML, 11 [4-12] for patients with allogenic stem cell transplantation and GvHD and 6 [3-12] for patients with lymphoproliferative disease. Treatment duration significantly differed according to country. Essential IPA biomarkers are not available in all European countries, and treatment duration is highly variable according to country. It will be important to provide guidelines to help with IPA treatment cessation with algorithms according to biomarker availability.