Treatment of Aspergillus terreus infections: a clinical problem not yet resolved

Aspergillosis: an Update on Clinical Spectrum, Diagnostic Schemes, and Management

Purpose of Review

This review gives an overview of the diseases caused by Aspergillus, including a description of the species involved and the infected clinical systems. We provide insight into the various diagnostic methods available for diagnosing aspergillosis, particularly invasive aspergillosis (IA), including the role of radiology, bronchoscopy, culture, and non-culture-based microbiological methods. We also discuss the available diagnostic algorithms for the different disease conditions. This review also summarizes the main aspects of managing infections due to Aspergillus spp., such as antifungal resistance, choice of antifungals, therapeutic drug monitoring, and new antifungal alternatives.

Recent Findings

The risk factors for this infection continue to evolve with the development of many biological agents that target the immune system and the increase of viral illnesses such as coronavirus disease. Due to the limitations of present mycological test methods, establishing a fast diagnosis is frequently difficult, and reports of developing antifungal resistance further complicate the management of aspergillosis. Many commercial assays, like AsperGenius®, MycAssay Aspergillus®, and MycoGENIE®, have the advantage of better species-level identification and concomitant resistance-associated mutations. Fosmanogepix, ibrexafungerp, rezafungin, and olorofim are newer antifungal agents in the pipeline exhibiting remarkable activity against Aspergillus spp.

Summary

The fungus Aspergillus is found ubiquitously around the world and can cause various infections, from harmless saprophytic colonization to severe IA. Understanding the diagnostic criteria to be used in different patient groups and the local epidemiological data and antifungal susceptibility profile is critical for optimal patient management.

Challenges in Serologic Diagnostics of Neglected Human Systemic Mycoses: An Overview on Characterization of New Targets

Systemic mycoses have been viewed as neglected diseases and they are responsible for deaths and disabilities around the world. Rapid, low-cost, simple, highly-specific and sensitive diagnostic tests are critical components of patient care, disease control and active surveillance. However, the diagnosis of fungal infections represents a great challenge because of the decline in the expertise needed for identifying fungi, and a reduced number of instruments and assays specific to fungal identification. Unfortunately, time of diagnosis is one of the most important risk factors for mortality rates from many of the systemic mycoses. In addition, phenotypic and biochemical identification methods are often time-consuming, which has created an increasing demand for new methods of fungal identification. In this review, we discuss the current context of the diagnosis of the main systemic mycoses and propose alternative approaches for the identification of new targets for fungal pathogens, which can help in the development of new diagnostic tests.

Aspergillus terreus and the Interplay with Amphotericin B: from Resistance to Tolerance?

Aspergillus terreus is an opportunistic causative agent of invasive aspergillosis and, in most cases, it is refractory to amphotericin B (AMB) therapy. Notably, AMB-susceptible Aspergillus terreus sensu stricto (s.s.) representatives exist which are also associated with poor clinical outcomes. Such findings may be attributable to drug tolerance, which is not detectable by antifungal susceptibility testing. Here, we tested in vitro antifungal susceptibility (AFST) and the fungicidal activity of AMB against 100 clinical isolates of A. terreus species complex in RPMI 1640 and antibiotic medium 3 (AM3). MICs ranged from 0.5 to 16 μg/mL for RPMI 1640 and from 1 to >16 mg/L for AM3. AMB showed medium-dependent activity, with fungicidal effects only in antibiotic medium 3, not in RPMI 1640. Furthermore, the presence of AMB-tolerant phenotypes of A. terreus has been examined by assessing the minimum duration for killing 99% of the population (MDK99) and evaluating the data obtained in a Galleria mellonella infection model. A time-kill curve analysis revealed that A. terreus with AMB MICs of ≤1 mg/L (susceptible range) displayed AMB-tolerant phenotypes, exhibiting MDK99s at 18 and 36 h, respectively. Survival rates of infected G. mellonella highlighted that AMB was effective against susceptible A. terreus isolates, but not against tolerant or resistant isolates. Our analysis reveals that A. terreus isolates which are defined as susceptible based on MIC may comprise tolerant phenotypes, which may, in turn, explain the worse outcome of AMB therapy for phenotypically susceptible isolates.

Aspergillus terreus Species Complex

Infections due to Aspergillus species are an acute threat to human health; members of the Aspergillus section Fumigati are the most frequently occurring agents, but depending on the local epidemiology, representatives of section Terrei or section Flavi are the second or third most important. Aspergillus terreus species complex is of great interest, as it is usually amphotericin B resistant and displays notable differences in immune interactions in comparison to Aspergillus fumigatus. The latest epidemiological surveys show an increased incidence of A. terreus as well as an expanding clinical spectrum (chronic infections) and new groups of at-risk patients being affected. Hallmarks of these non-Aspergillus fumigatus invasive mold infections are high potential for tissue invasion, dissemination, and possible morbidity due to mycotoxin production. We seek to review the microbiology, epidemiology, and pathogenesis of A. terreus species complex, address clinical characteristics, and highlight the underlying mechanisms of amphotericin B resistance. Selected topics will contrast key elements of A. terreus with A. fumigatus. We provide a comprehensive resource for clinicians dealing with fungal infections and researchers working on A. terreus pathogenesis, aiming to bridge the emerging translational knowledge and future therapeutic challenges on this opportunistic pathogen.

Fatal invasive pulmonary aspergillosis in an immunocompetent patient with COVID-19 due to Aspergillus terreus: A case study

Case reports of CAPA emerged. In most of the reports, the predominant species is Aspergillus fumigatus. Uncommon species are less reported. Due to poor clinical outcome with Aspergillus terreus, the increasing reports with this agent require attention.

The Environmental Spread of Aspergillus terreus in Tyrol, Austria

Fungal infections due to Aspergillus species have become a major cause of morbidity and mortality among immunocompromised patients. At the Medical University of Innsbruck, A. terreus and related species are the second most common causative agents of aspergillosis. In this one-year study we collected environmental samples to investigate (i) the environmental distribution, (ii) the ecological niche of A. terreus in Tyrol, (iii) the genetic relatedness of environmental and clinical isolates and the correlation between those two groups of isolates, and (iv) the antifungal susceptibility patterns. A. terreus was present in 5.4% of 3845 environmental samples, with a significantly higher frequency during winter (6.8%) than summer (3.9%). An increased A. terreus abundance in Tyrol’s Eastern part was detected which is in agreement with the proof of clinical cases. In total, 92% of environmental and 98% of clinical A. terreus isolates were amphotericin B resistant; 22.6% and 9.8% were resistant against posaconazole. Overall, 3.9% of clinical isolates were resistant against voriconazole. Short tandem repeat analysis identified three major genotypes persisting in Tyrol. Soil from agricultural cornfields seems to be an important source; the environmental frequency of A. terreus correlates with the high incidence of A. terreus infections in certain geographical areas.

Clinical Accuracy and Impact of Plasma Cell-Free DNA Fungal PCR Panel for Non-Invasive Diagnosis of Fungal Infection

BACKGROUND

Invasive fungal infection (IFI) is a growing cause of morbidity and mortality in oncology and transplant patients. Diagnosis of IFI is often delayed due to need for invasive biopsy and low sensitivity of conventional diagnostic methods. Fungal cell-free DNA (cfDNA) detection in plasma is a novel testing modality for the non-invasive diagnosis of IFI.

METHODS

A novel bioinformatic pipeline was created to interrogate fungal genomes and identify multicopy sequences for cfDNA PCR targeting. A real-time PCR panel was developed for 12 genera and species most commonly causing IFI. Sensitivity and specificity of the fungal PCR panel were determined using plasma samples from patients with IFI and non-IFI controls. Clinical impact of fungal PCR panel was evaluated prospectively based on the treating team's interpretation of the results.

RESULTS

Overall, the sensitivity and specificity were 56.5% (65/115, 95% confidence interval [CI], 47.4%-65.2%) and 99.5% (2064/2075; 95% CI, 99.0%-99.7%), respectively. In the subset of patients with an optimized plasma volume (2mL), sensitivity was 69.6% (48/69; 95% CI, 57.9%-79.2%). Sensitivity was 91.7% (11/12; 95% CI, 62.5%-100%) for detection of Mucorales agents, 56.3% (9/16; 95% CI, 33.2%-76.9%) for Aspergillus species, and 84.6% (11/13; 95% CI, 56.5%-96.9%) for Candida albicans. In a prospective evaluation of 226 patients with suspected IFI, cfDNA testing was positive in 47 (20.8%) patients and resulted in a positive impact on clinical management in 20/47 (42.6%).

CONCLUSIONS

The fungal cfDNA PCR panel offers a non-invasive approach to early diagnosis of IFI, providing actionable results for personalized care.

Complete genome sequence of lovastatin producer Aspergillus terreus ATCC 20542 and evaluation of genomic diversity among A. terreus strains

Abstract

In the present study, the complete genome of a filamentous fungus Aspergillus terreus ATCC 20542 was sequenced, assembled, and annotated. This strain is mainly recognized for being a model wild-type lovastatin producer and a parental strain of high-yielding industrial mutants. It is also a microorganism with a rich repertoire of secondary metabolites that has been a subject of numerous bioprocess-related studies. In terms of continuity, the genomic sequence provided in this work is of the highest quality among all the publicly available genomes of A. terreus strains. The comparative analysis revealed considerable diversity with regard to the catalog of biosynthetic gene clusters found in A. terreus. Even though the cluster of lovastatin biosynthesis was found to be well-conserved at the species level, several unique genes putatively associated with metabolic functions were detected in A. terreus ATCC 20542 that were not detected in other investigated genomes. The analysis was conducted also in the context of the primary metabolic pathways (sugar catabolism, biomass degradation potential, organic acid production), where the visible differences in gene copy numbers were detected. However, the species-level genomic diversity of A. terreus was more evident for secondary metabolism than for the well-conserved primary metabolic pathways. The newly sequenced genome of A. terreus ATCC 20542 was found to harbor several unique sequences, which can be regarded as interesting subjects for future experimental efforts on A. terreus metabolism and fungal biosynthetic capabilities.

Key points

• The high-quality genome of Aspergillus terreus ATCC 20542 has been assembled and annotated.

• Comparative analysis with other sequenced Aspergillus terreus strains has revealed considerable diversity in biosynthetic gene repertoire, especially related to secondary metabolism.

• The unique genomic features of A. terreus ATCC 20542 are discussed.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00253-021-11133-0.

Prosthetic Finger Joint Infection Due to Aspergillus terreus

Fungal periprosthetic joint infections (PJIs) are rare but associated with significant mortality. We report a case of a finger PJI secondary to Aspergillus terreus in an immunocompetent patient with soil exposure, successfully treated with surgical debridement and voriconazole. Identification of A terreus is important because of intrinsic amphotericin B resistance.

Molecular identification, phylogenetic analysis and antifungal susceptibility patterns of Aspergillusnidulans complex and Aspergillusterreus complex isolated from clinical specimens

OBJECTIVE

Aspergillus sections Terrei and Nidulantes are the less common causes of invasive aspergillosis and pulmonary aspergillosis (PA) in immunocompromised patients when compared to A. fumigatus and A. flavus. Identifying these fungi as the infectious agent is crucial because of the resistance to amphotericin B (AMB) and increased lethality. The aim of this study was to identify the molecular status, evaluate the genetic diversity and examine the antifungal susceptibility profile of the uncommon Aspergillus species. Forty-five uncommon Aspergillus species were identified based on the microscopic and macroscopic criteria. Then, the molecular identification was performed using the sequencing beta tubulin (benA) gene. In vitro antifungal susceptibility to amphotericin B (AMB), itraconazole (ITC), ravuconazole (RAV), voriconazole (VRC), caspofungin (CFG) isavuconazole (ISA) and posaconazole (POS) test was performed according to the CLSI M38-A2 guidelines.

RESULTS

A. terreus was the most species detected, followed by A. nidulans, A. latus, A.ochraceus, and A. citrinoterreus, respectively. The analysis of the benA gene showed the presence of 12 distinct genotypes among the A. terreus isolates. The other species did not show any intraspecies variation. CFG exhibited the lowest MEC₅₀/MIC₅₀ (0.007μg/mL), followed by POS (0.125μg/mL), VRC, ITC, ISA (0.25μg/mL), RAV (0.5μg/mL), and AMB (8μg/mL). Among all the isolates, only 15.5% (7/45) were susceptible to AMB.

CONCLUSION

Antifungal susceptibility pattern of the uncommon Aspergillus species is useful to improve patient management and increase knowledge concerning the local epidemiology. Moreover, this information is necessary when an outbreak dealing with drug-resistant infections occurs.

Fungal Placentitis Caused by Aspergillus terreus in a Mare: Case Report

Placentitis has been reported as the most important cause of equine abortions, stillbirths, and perinatal deaths in horses. Most cases are caused by bacteria and less commonly by fungal elements. The aim of this report is to describe the clinical presentation of a fungal placentitis caused by Aspergillus terrerus. A 5-year-old thoroughbred maiden mare at the 217th day of gestation presented with some classic signs of placentitis (premature udder development and milk dripping). All ultrasonographic findings were consistent with a live fetus and a severe placentitis. On vaginal examination, purulent discharge was found coming from the external cervical os. Samples sent for culture yielded very small numbers of mixed growth including Enterococcus faecalis (by matrix-assisted laser desorption/ionization time-of-flight mass spectrometer), Streptococcus viridans, and Aspergillus terreus, and polymerase chain reaction was positive for Aspergillus terreus and Pseudomonas. The mare was placed on broad-spectrum antimicrobials, nonsteroidal anti-inflammatories, and hormonal and antifungal treatment. The fetus kept on developing and growing despite the placentitis for 14 days until the demise of the fetus in utero occurred. Aspergillus terreus was isolated from the chorionic surface but not from the fetus. Fungal placentitis is not very commonly found in mares. The extent of the placental lesions and the severity of the placentitis contributed to the death of the fetus. This is one of the few case reports available describing fungal placentitis. Aspergillus terreus has not been previously reported as a cause of placentitis.

Resistance mechanism and proteins in Aspergillus species against antifungal agents

Aspergillus

species contain pathogenic and opportunistic fungal pathogens which have the potential to cause mycosis (invasive aspergillosis) in humans. The existing antifungal drugs have limitation largely due to the development of drug-resistant isolates. To gain insight into the mechanism of action and antifungal drug resistance in Aspergillus species including biofilm formation, we have reviewed protein data of Aspergillus species during interaction with antifungals drugs (polynes, azoles and echinocandin) and phytochemicals (artemisinin, coumarin and quercetin). Our analyses provided a list of Aspergillus proteins (72 proteins) that were abundant during interaction with different antifungal agents. On the other hand, there are 26 proteins, expression level of which is affected by more than two antifungal agents, suggesting the more general response to the stress induced by the antifungal agents. Our analysis showed enzymes from cell wall remodelling, oxidative stress response and energy metabolism are the responsible factors for providing resistance against antifungal drugs in Aspergillus species and could be explored further in clinical isolates. Also, these findings have clinical importance since the effect of drug targeting different proteins can be potentiated by combination therapy. We have also discussed the opportunities ahead to study the functional role of proteins from environmental and clinical isolates of Aspergillus during its interaction with the antifungal drugs.

Abbreviations

IPA: invasive pulmonary aspergillosis; IA: invasive aspergillosis; AmB: Amphotericin B; CAS: Caspofungin; VRC: Voriconazole; ITC: Itraconazole; POS: Posaconazole; ART: Artemisinin; QRT: Quercetin; CMR: Coumarin; MIC: minimal inhibitory concentration

Aspergillus terreus (Trichocomaceae): A Natural, Eco-Friendly Mycoinsecticide for Control of Malaria, Filariasis, Dengue Vectors and Its Toxicity Assessment Against an Aquatic Model Organism Artemia nauplii

Vector-borne diseases like malaria, filariasis, and dengue are transmitted by mosquitoes and they cause global mortality and morbidity due to an increased resistance against commercial insecticides. The present study was aimed to evaluate the neurobehavioral toxicity, knock-down effect, histopathology, ovicidal, adulticidal, and smoke toxicity effect of Aspergillus terreus extract against three mosquito species, namely Anopheles stephensi, Culex quinquefasciatus, and Aedes aegypti (Diptera: Culicidae). The isolated fungal strain was identified as A. terreus (GenBank accession no: KX694148.1) through morphological and molecular (phylogenetic) analysis. The morphological changes in the treated fourth instar larvae shown the demelanization of cuticle and shrinkage of the internal cuticle of anal papillae. The time duration of extract exposure against the larvae determines the level of toxicity. The extract treated larvae were displayed excitation, violent vertical and horizontal movements with aggressive anal biting behavior as the toxic effect on the neuromuscular system. The results of the biochemical analysis indicated that a decrease in the level of acetylcholinesterase, α-carboxylesterase, and β-carboxylesterase in extract treated fourth instar larvae of all tested mosquito species. The findings of histopathological investigation shown the disorganization of the abdominal region, mainly in mid, hindgut, and gastric caeca, loss of antenna, lateral hair, caudal hair, upper and lower head hairs in the mycelium extract treated An. stephensi, Cx. quinquefasciatus, and Ae. aegypti. The ovicidal bioassay test results showed the mosquito hatchability percentage was directly related to the concentrations of mycelium extract. Nil hatchability of mosquito eggs was noticed at 500 μg/ml concentration. The adulticidal activity of fungal mycelia ethyl acetate extract resulted in a dose-dependent activity (15 and 30 min recovery periods). The higher concentration of extract (1000 mg/L) acted as a repellent, the adult mosquitoes showed restless movement, uncontrolled/anesthetic flight at last died. The better adulticidal activity was observed in the ethyl acetate extract against An. stephensi, Cx. quinquefasciatus followed by Ae. aegypti with the best score of LD50 and LD90 values and nil mortality was found in the control. The results of smoke toxicity assay of the mycelia extract exhibited significant mortality rate against Ae. aegypti (91%), Cx. quinquefasciatus (89%), and An. stephensi (84%). In addition, the present investigation reported the stability and toxic effects of A. terreus mycelium ethyl acetate extract on Artemia nauplii. The swimming speed (0.88 mm s-1) of A. terreus was reduced with ethyl extract 24 h treatment whereas, the control A. nauplii showed the normal speed of 2.96 mm s-1. Altered behavior and swimming movement were observed in the 8 h A. terreus mycelium extract treated A. nauplii. A pale yellow color substance (metabolites) was found in the mid-gut region of the mycelial extract exposed A. nauplii. The outcome of the present study, suggest that the A. terreus metabolites might serve as an alternative, cost-effective, eco-friendly, and target specific mosquitocidal agent in the future.

An adult autosomal recessive chronic granulomatous disease patient with pulmonary Aspergillus terreus infection

Background

Genetic mutations that reduce intracellular superoxide production by granulocytes causes chronic granulomatous disease (CGD). These patients suffer from frequent and severe bacterial and fungal infections throughout their early life. Diagnosis is usually made in the first 2 years of life but is sometimes only diagnosed when the patient is an adult although they may have suffered from symptoms since childhood.

Case presentation

A 26-year-old man was referred with weight loss, fever, hepatosplenomegaly and coughing. He had previously been diagnosed with lymphadenopathy in the neck at age 8 and prescribed anti-tuberculosis treatment. A chest radiograph revealed extensive right-sided consolidation along with smaller foci of consolidation in the left lung. On admission to hospital he had respiratory problems with fever. Laboratory investigations including dihydrorhodamine-123 (DHR) tests and mutational analysis indicated CGD. Stimulation of his isolated peripheral blood neutrophils (PMN) with phorbol 12-myristate 13-acetate (PMA) produced low, subnormal levels of reactive oxygen species (ROS). Aspergillus terreus was isolated from bronchoalveolar lavage (BAL) fluid and sequenced.

Conclusions

We describe, for the first time, the presence of pulmonary A. terreus infection in an adult autosomal CGD patient on long-term corticosteroid treatment. The combination of the molecular characterization of the inherited CGD and the sequencing of fungal DNA has allowed the identification of the disease-causing agent and the optimal treatment to be given as a consequence.

Therapy of Non-Dermatophytic Mycoses in Animals

This review focuses on aspects of antimycotic therapy specific to veterinary medicine. In the first part, drug availability, limited mostly by economic consideration but also by clinical applicability and specific adverse effects, is described for polyenes, 5 fluorocytosine, azoles, echinocandins and terbinafine. In the second part, current knowledge and experience in the treatment of selected fungal infections are overviewed. These mycoses include disseminated mold infections in small animals (dogs and cats) and avian species, upper respiratory tract infections of small animals (sino-nasal and sino-orbital aspergillosis) and horses (guttural pouch mycosis), eumycetoma, infections caused by dimorphic fungi, (blastomycosis, histoplasmosis, coccidioidomycosis, paracoccidioidomycosis and sporothrichosis) and by yeasts and yeast-like microorganism (Cryptococcus spp. and Malassezia pachydermatis).

Prevalence and in vitro antifungal susceptibility of cryptic species of the genus Aspergillus isolated in clinical samples

INTRODUCTION

The genus Aspergillus contains more than 300 species, which are divided into closely related groups called sections. Molecular studies have revealed numerous cryptic species within different sections of this genus, which have different profiles of antifungal susceptibility and lack diagnostic morphological features. However, there are few studies on the prevalence and in vitro antifungal susceptibility of the cryptic species of this genus. The aim of this study was to investigate the distribution of Aspergillus spp. among clinical samples, and to study their in vitro susceptibility to different antifungal drugs.

METHOD

Over a period of 2-years (2014-2015), a total of 379 strains of the genus Aspergillus were isolated. Most of the isolates were classified as respiratory colonizations; no cases of invasive aspergillosis were found. The strains were identified by MALDI-TOF mass spectrometry, and susceptibility testing was performed by the EUCAST reference procedure.

RESULTS

Twenty species belonging to 8 sections were identified, being A. fumigatus the most prevalent (44.1%). The prevalence of cryptic species was 15.3%, with a clear predominance of A. tubingensis. Among the tested antifungal drugs, amphotericin B was the less active in vitro, followed by triazole drugs and echinocandins. The cryptic species had minimun inhibitory concentrations (MICs) higher than the corresponding type species.

CONCLUSIONS

Accurate identification of the genus Aspergillus at the species level and in vitro antifungal susceptibility testing are necessary because, as it has been shown, some species of this genus may show resistance profiles against available antifungal drugs.

Adjunctive interferon-γ immunotherapy in a pediatric case of Aspergillus terreus infection

Aspergillus terreus causes invasive aspergillosis (IA) in immunocompromised patients. Treatment is complicated by intrinsic resistance to amphotericin B and thereby contributing to a high mortality. Therefore, we conducted in vitro studies to investigate the effectivity of adjunctive recombinant interferon-γ immunotherapy. We describe a pediatric patient with A. terreus IA who received adjunctive recombinant interferon-γ (rIFNγ) immunotherapy. In vitro studies were conducted to investigate the capacity of rIFNγ to improve antifungal host defense in terms of fungal killing ability and the release of pro-inflammatory cytokines in cells of the patient as well as healthy controls. An 8-year-old female pediatric patient with leukemia developed A. terreus IA. She clinically deteriorated and had high serum galactomannan levels despite broad antifungal therapy. Therefore, adjunctive immune stimulatory therapy with rIFNγ was initiated. After 3 weeks of treatment, galactomannan levels decreased and the patient clinically showed improvement. Addition of rIFNγ boosted the capacity of monocytes of healthy volunteers to mount TNFα and IL-1β cytokine responses to Escherichia coli LPS, and increased TNFα response to both A. terreus and Aspergillus fumigatus. Monocytes isolated from the patient's blood demonstrated a similar augmented cytokine induction in response to rIFNγ. In addition, rIFNγ increased the capacity of monocytes from healthy volunteers as well as monocytes from the patient to kill A. terreus spores. Adjuvant immunotherapy with rIFNγ might be a promising additional treatment strategy that could be used to improve outcome in patients with refractory invasive A. terreus infections or other resistant invasive Aspergillus infections.

Treatment of Infections Due to Aspergillus terreus Species Complex

The Aspergillus terreus species complex is found in a wide variety of habitats, and the spectrum of diseases caused covers allergic bronchopulmonary aspergillosis, Aspergillus bronchitis and/or tracheobronchitis, and invasive and disseminated aspergillosis. Invasive infections are a significant cause of morbidity and mortality mainly in patients with hematological malignancy. The section Terrei covers a total of 16 accepted species of which most are amphotericin B resistant. Triazoles are the preferred agents for treatment and prevention of invasive aspergillosis. Poor prognosis in patients with invasive A. terreus infections seems to be independent of anti-Aspergillus azole-based treatment.

Surveillance for azoles resistance in Aspergillus spp. highlights a high number of amphotericin B-resistant isolates

Aspergillus spp. are the most common invasive mould infection and are responsible for high mortality. Aspergillus fumigatus is currently of interest because resistance to azole antifungals has emerged. The Campinas University Hospital (HC-UNICAMP) receives high-risk patients susceptible to opportunistic infections but there have been no reports of resistant A. fumigatus. This study aimed to assess the susceptibility profile of Aspergillus isolates, specifically looking for azole resistance. ITS and β-tubulin DNA sequencing was performed on 228 sequential clinical isolates. Broth microdilution susceptibility testing was performed for all isolates. A. fumigatus represented 74% of the isolates followed by Aspergillus flavus (12%). Nine A. fumigatus isolates from 9 different patients showed high MIC values to at least 1 azole, but cyp51A polymorphisms were detected in only 6 isolates and none correlated with known resistance mutations. The most troubling observation was that the minimum inhibitory concentration for amphotericin B was elevated (≥2 mg L^-1 ) in 87% of patients with A. flavus isolates and 43% with Aspergillus fumigatus isolates. Given that amphotericin B is used to treat azole-resistant infections, these data highlight the need for continuous surveillance in Aspergillus for all antifungal resistance to implement correct treatment strategies for the management of these pathogens.

In vitro antifungal activity of amphotericin B and 11 comparators against Aspergillus terreus species complex

Aspergillus terreus infections are difficult to treat because of the intrinsic resistance to amphotericin B, and higher mortality compared to infections caused by other Aspergillus species. The aim of the present study was to determine the in vitro antifungal activity of amphotericin B and 11 comparators against clinical (n = 36) and environmental (n = 45) A. terreus isolates. In vitro antifungal susceptibility was performed using the CLSI M38-A2 procedure. Amphotericin B exhibited the highest MICs (MIC range, 0.125-4 μg/mL; MIC₉₀ , 2 μg/mL), followed by terbinafine (MIC range, 0.002-1 μg/mL; MIC₉₀ , 1 μg/mL). Only one isolate (1/81) showed amphotericin B MIC above the epidemiologic cut-off value (ECV; 4 μg/mL). None of the isolates had a MIC of ≥ ECV for voriconazole, itraconazole and posaconazole. The reasons for the difference in amphotericin B susceptibility patterns between studies remain unknown. The genetic and species diversity, clinical, environmental and ecological factors in Terrei section on various amphotericin B susceptibility profiles in different countries should be considered more as the main reasons associated with these differences.

Persistence within dendritic cells marks an antifungal evasion and dissemination strategy of Aspergillus terreus

Aspergillus terreus is an airborne human fungal pathogen causing life-threatening invasive aspergillosis in immunocompromised patients. In contrast to Aspergillus fumigatus, A. terreus infections are associated with high dissemination rates and poor response to antifungal treatment. Here, we compared the interaction of conidia from both fungal species with MUTZ-3-derived dendritic cells (DCs). After phagocytosis, A. fumigatus conidia rapidly escaped from DCs, whereas A. terreus conidia remained persisting with long-term survival. Escape from DCs was independent from DHN-melanin, as A. terreus conidia expressing wA showed no increased intracellular germination. Within DCs A. terreus conidia were protected from antifungals, whereas A. fumigatus conidia were efficiently cleared. Furthermore, while A. fumigatus conidia triggered expression of DC activation markers such as CD80, CD83, CD54, MHCII and CCR7, persistent A. terreus conidia were significantly less immunogenic. Moreover, DCs confronted with A. terreus conidia neither produced pro-inflammatory nor T-cell stimulating cytokines. However, TNF-α addition resulted in activation of DCs and provoked the expression of migration markers without inactivating intracellular A. terreus conidia. Therefore, persistence within DCs and possibly within other immune cells might contribute to the low response of A. terreus infections to antifungal treatment and could be responsible for its high dissemination rates.

Luliconazole, an alternative antifungal agent against Aspergillus terreus

Aspergillus terreus is the fourth leading cause of invasive and non-invasive aspergillosis and one of the causative agents of morbidity and mortality among immunocompromised and high-risk patients. A. terreus appears to have increased as a cause of opportunistic fungal infections from superficial to serious invasive infections. Although, invasive aspergillosis is often treated empirically with amphotericin B, most A. terreus isolates are resistant both in vivo and in vitro to some antifungal drugs. In this study, we aimed to evaluate antifungals susceptibility profiles of the different strains of A. terreus against amphotericin B, caspofungin, fluconazole, voriconazole, posaconazole and luliconazole. Forty A. terreus strains originating from environmental sources (air and soil) were identified using by macroscopic and microscopic features. Six antifungals including, amphotericin B, caspofungin, fluconazole, voriconazole, posaconazole and luliconazole were applied for susceptibility tests. Our results show that tested isolates had different susceptibility to antifungals. The lowest MIC_GM related to luliconazole (0.00236μg/ml), followed by posaconazole (0.18621μg/ml), voriconazole (0.22925μg/ml), caspofungin (0.86μg/ml), fluconazole (8μg/ml) and amphotericin B (11.12μg/ml). This study demonstrated that luliconazole had an excellent in vitro activity against all tested isolates of A. terreus, with MIC_GM 0.00236μg/mL than other tested antifungals. As a result, luliconazole could be a possible alternative antifungal for the treatment of aspergillosis due to A. terreus.

Diversity, Application, and Synthetic Biology of Industrially Important Aspergillus Fungi

The filamentous fungal genus Aspergillus consists of over 340 officially recognized species. A handful of these Aspergillus fungi are predominantly used for food fermentation and large-scale production of enzymes, organic acids, and bioactive compounds. These industrially important Aspergilli primarily belong to the two major Aspergillus sections, Nigri and Flavi. Aspergillus oryzae (section Flavi) is the most commonly used mold for the fermentation of soybeans, rice, grains, and potatoes. Aspergillus niger (section Nigri) is used in the industrial production of various enzymes and organic acids, including 99% (1.4 million tons per year) of citric acid produced worldwide. Better understanding of the genomes and the signaling mechanisms of key Aspergillus species can help identify novel approaches to enhance these commercially significant strains. This review summarizes the diversity, current applications, key products, and synthetic biology of Aspergillus fungi commonly used in industry.

Agents that activate the High Osmolarity Glycerol pathway as a means to combat pathogenic molds

Treatment of invasive fungal infections often fails due to the limited number of therapeutic options. In this study, we have analyzed the impact of agents activating the High Osmolarity Glycerol (HOG) pathway on molds that cause infections in humans and livestock. We found that agents like fludioxonil and iprodione, have a clear anti-fungal activity against pathogenic Aspergillus, Lichtheimia, Rhizopus and Scedosporium species. Only A. terreus turned out to be resistant to fludioxonil, even though it is sensitive to iprodione and able to adapt to hyperosmotic conditions. Moreover, the A. terreus tcsC gene can fully complement an A. fumigatus ΔtcsC mutant, thereby also restoring its sensitivity to fludioxonil. The particular phenotype of A. terreus is therefore likely to be independent of its TcsC kinase. In a second part of this study, we further explored the impact of fludioxonil using A. fumigatus as a model organism. When applied in concentrations of 1-2μg/ml, fludioxonil causes an immediate growth arrest and, after longer exposure, a quantitative killing. Hyphae respond to fludioxonil by the formation of new septa and closure of nearly all septal pores. Mitosis occurs in all compartments and is accompanied by a re-localization of the NimA kinase to the cytoplasm. In the swollen compartments, the massive extension of the cell wall triggers a substantial reorganization resulting in an enhanced incorporation of chitin and, most strikingly, a massive loss of galactomannan. Hence, HOG-activating agents have dramatic cell biological consequences and may represent a valuable, future element in the armory that can be used to combat mold infections.

Geographically predominant genotypes of Aspergillus terreus species complex in Austria: s microsatellite typing study

Aspergillus terreus species complex is recognized as a frequent agent of invasive aspergillosis in Tyrol. The reason for this specific epidemiological situation is unclear. Aspergillus terreus strains isolated from environmental and clinical sources were genotyped using a novel panel of short tandem repeats and were evaluated for virulence. Three major endemic genotypes collected from the Inn region and its side valleys were found to cause the majority of invasive A. terreus infections. All of these genotypes were of the same mating type, which suggests that a mating barrier is present between these geographically well-adapted strains which is found to persist for at least 11 years. The three major genotypes were prevalent in both human infections and the environment. No major differences in virulence were observed using Galleria mellonella as model. Our data suggest a specific environmental exposure being responsible for the high incidence of A. terreus infections in Innsbruck, the Inn valley and side valleys (Tyrol, Austria).

Blocking Hsp70 enhances the efficiency of amphotericin B treatment against resistant Aspergillus terreus strains

The polyene antifungal amphotericin B (AmB) is widely used to treat life-threatening fungal infections. Even though AmB resistance is exceptionally rare in fungi, most Aspergillus terreus isolates exhibit an intrinsic resistance against the drug in vivo and in vitro. Heat shock proteins perform a fundamental protective role against a multitude of stress responses, thereby maintaining protein homeostasis in the organism. In this study, we elucidated the role of heat shock protein 70 (Hsp70) family members and compared resistant and susceptible A. terreus clinical isolates. The upregulation of cytoplasmic Hsp70 members at the transcriptional as well as translational levels was significantly higher with AmB treatment than without AmB treatment, particularly in resistant A. terreus isolates, thereby indicating a role of Hsp70 proteins in the AmB response. We found that Hsp70 inhibitors considerably increased the susceptibility of resistant A. terreus isolates to AmB but exerted little impact on susceptible isolates. Also, in in vivo experiments, using the Galleria mellonella infection model, cotreatment of resistant A. terreus strains with AmB and the Hsp70 inhibitor pifithrin-μ resulted in significantly improved survival compared with that achieved with AmB alone. Our results point to an important mechanism of regulation of AmB resistance by Hsp70 family members in A. terreus and suggest novel drug targets for the treatment of infections caused by resistant fungal isolates.