Targeting Sterylglucosidase A to Treat Aspergillus fumigatus Infections.

Invasive fungal infections are a leading cause of death in immunocompromised patients. Current therapies have several limitations, and innovative antifungal agents are critically needed. Previously, we identified the fungus-specific enzyme sterylglucosidase as essential for pathogenesis and virulence of Cryptococcus neoformans and Aspergillus fumigatus (Af) in murine models of mycoses. Here, we developed Af sterylglucosidase A (SglA) as a therapeutic target. We identified two selective inhibitors of SglA with distinct chemical scaffolds that bind in the active site of SglA. Both inhibitors induce sterylglucoside accumulation and delay filamentation in Af and increase survival in a murine model of pulmonary aspergillosis. Structure-activity relationship (SAR) studies identified a more potent derivative that enhances both in vitro phenotypes and in vivo survival. These findings support sterylglucosidase inhibition as a promising antifungal approach with broad-spectrum potential. IMPORTANCE Invasive fungal infections are a leading cause of death in immunocompromised patients. Aspergillus fumigatus is a fungus ubiquitously found in the environment that, upon inhalation, causes both acute and chronic illnesses in at-risk individuals. A. fumigatus is recognized as one of the critical fungal pathogens for which a substantive treatment breakthrough is urgently needed. Here, we studied a fungus-specific enzyme, sterylglucosidase A (SglA), as a therapeutic target. We identified selective inhibitors of SglA that induce accumulation of sterylglucosides and delay filamentation in A. fumigatus and increase survival in a murine model of pulmonary aspergillosis. We determined the structure of SglA, predicted the binding poses of these inhibitors through docking analysis, and identified a more efficacious derivative with a limited SAR study. These results open several exciting avenues for the research and development of a new class of antifungal agents targeting sterylglucosidases.

Invasive cerebral aspergillosis in non-neutropenic patients: A case series from Western India.

PURPOSE: Invasive cerebral aspergillosis (ICA) is a rare but fatal infection affecting neutropenic immunocompromised patients. Recently cases have been reported in non-neutropenic settings also. We hereby present a series of ICA cases in non-neutropenic patients diagnosed at our tertiary care centre in Western India between March to October 2021. METHODS: All patients with clinico-radiological suspicion of CNS infections were analysed. Data regarding Clinico-radiological features, diagnosis, treatment and outcome were collected. After ruling out bacterial, viral and mycobacterial causes, appropriate samples were sent for KOH (potassium hydroxide) wet mount, fungal culture, histopathology and serum/CSF galactomannan. RESULTS: A total of four patients were diagnosed with ICA with a mean age of 43.5 years. Three patients had significant comorbidities; Diabetes mellitus, chronic liver disease and COVID-19 pneumonia treated with dexamethasone, respectively. One patient had no known predisposing factor. Radiologically, one patient presented with a frontal brain abscess and two patients had multiple subcortical hyperintensities. Three patients were diagnosed based on CSF galactomannan (Platelia™ Aspergillus antigen, Bio-Rad, France) with OD >1 and one patient had high serum galactomannan (OD >2). CSF culture grew Aspergillus species in two patients. All patients were treated with Voriconazole. One patient recovered, and the remaining three succumbed due to delayed presentation and extensive cerebral involvement. CONCLUSION: Even in non-neutropenic patients, a high index of suspicion is warranted for cerebral aspergillosis. CSF galactomannan can be considered a reliable marker for diagnosing ICA in non-neutropenic settings. Early diagnosis allows timely antifungal therapy, which could be a key to improving the outcomes.

Characterization of Aspergillus spp. isolated from patients with coronavirus disease 2019.

INTRODUCTION: Invasive pulmonary aspergillosis (IPA) is an important complication of coronavirus disease 2019 (COVID-19), and while there are case reports and epidemiological studies, few studies have isolated Aspergillus strains from patients. Therefore, we analyzed the strains, sensitivities, and genetic homology of Aspergillus spp. Isolated from patients with COVID-19. METHODS: We investigated the Aspergillus strains detected from patients with COVID-19 hospitalized in Osaka Metropolitan University Hospital from December 2020 to June 2021. A molecular epidemiological analysis of Aspergillus spp. was performed using drug susceptibility tests and TRESPERG typing, and data on patient characteristics were collected from electronic medical records. RESULTS: Twelve strains of Aspergillus were detected in 11 of the 122 patients (9%) with COVID-19. A. fumigatus was the most common species detected, followed by one strain each of Aspergillus aureolus, Aspergillus nidulans, Aspergillus niger, and Aspergillus terreus. A. aureolus was resistant to voriconazole, and no resistance was found in other strains. All A. fumigatus strains were genetically distinct strains. Six of the 11 patients that harbored Aspergillus received antifungal drug treatment and tested positive for ß-D-glucan and/or Aspergillus galactomannan antigen. The results indicated that Aspergillus infections were acquired from outside the hospital and not from nosocomial infections. CONCLUSION: Strict surveillance of Aspergillus spp. is beneficial in patients at high-risk for IPA. When Aspergillus is detected, it is important to monitor the onset of IPA carefully and identify the strain, perform drug sensitivity tests, and facilitate early administration of therapeutic agents to patients with IPA.

Consensus guidelines for the diagnosis and management of invasive aspergillosis, 2021.

Invasive aspergillosis (IA) in haematology/oncology patients presents as primary infection or breakthrough infection, which can become refractory to antifungal treatment and has a high associated mortality. Other emerging patient risk groups include patients in the intensive care setting with severe respiratory viral infections, including COVID-19. These guidelines present key diagnostic and treatment recommendations in light of advances in knowledge since the previous guidelines in 2014. Culture and histological-based methods remain central to the diagnosis of IA. There is increasing evidence for the utility of non-culture methods employing fungal biomarkers in pre-emptive screening for infection, as well as for IA diagnosis when used in combination. Although azole resistance appears to be uncommon in Australia, susceptibility testing of clinical Aspergillus fumigatus complex isolates is recommended. Voriconazole remains the preferred first-line antifungal agent for treating primary IA, including for extrapulmonary disease. Recommendations for paediatric treatment broadly follow those for adults. For breakthrough and refractory IA, a change in class of antifungal agent is strongly recommended, and agents under clinical trial may need to be considered. Newer immunological-based imaging modalities warrant further study, while surveillance for IA and antifungal resistance remain essential to informing the relevance of current treatment recommendations.

Unique presentations of aspergillosis endogenous endophthalmitis in two hospitalized patients with severe COVID-19.

We present two ICU-hospitalized patients with coronavirus disease-19 (COVID-19) presenting with endogenous endophthalmitis in one eye and variable manifestations of chorioretinitis in the fellow eye. Two diabetic patients (57 and 62 years old) showed anterior uveitis and yellowish-white subretinal infiltrations. The fellow eye of one patient showed patches of choroiditis, while the other showed full retinal thickness infiltrations. A workup yielded high serum titers of galactomannan, diagnostic of aspergillosis. The widespread use of high doses of corticosteroids in the management of COVID-19 may predispose to various secondary fungal opportunistic infections and may manifest in different forms of chorioretinal infiltration.

Monoclonal Antibodies and Invasive Aspergillosis: Diagnostic and Therapeutic Perspectives.

Invasive aspergillosis (IA) is a life-threatening fungal disease that causes high morbidity and mortality in immunosuppressed patients. Early and accurate diagnosis and treatment of IA remain challenging. Given the broad range of non-specific clinical symptoms and the shortcomings of current diagnostic techniques, most patients are either diagnosed as "possible" or "probable" cases but not "proven". Moreover, because of the lack of sensitive and specific tests, many high-risk patients receive an empirical therapy or a prolonged treatment of high-priced antifungal agents, leading to unnecessary adverse effects and a high risk of drug resistance. More precise diagnostic techniques alongside a targeted antifungal treatment are fundamental requirements for reducing the morbidity and mortality of IA. Monoclonal antibodies (mAbs) with high specificity in targeting the corresponding antigen(s) may have the potential to improve diagnostic tests and form the basis for novel IA treatments. This review summarizes the up-to-date application of mAb-based approaches in assisting IA diagnosis and therapy.

Aspergillus endocarditis in the recent years, report of cases of a multicentric national cohort and literature review.

OBJECTIVES: (1) To describe the incidence, clinical characteristics, treatment and outcome of Aspergillus Endocarditis (AE) in a nationwide multicentric cohort (GAMES). (2) To compare the AE cases of the GAMES cohort, with the AE cases reported in the literature since 2010. (3) To identify variables related to mortality. METHODS: We recruited 10 AE cases included in the GAMES cohort (January 2008-December 2018) and 51 cases from the literature published from January 2010 to July 2019. RESULTS: 4528 patients with infectious endocarditis (IE) were included in the GAMES cohort, of them 10 (0.2%) were AE. After comparing our 10 cases with the 51 of the literature, no differences were found. Analysing the 61 AE cases together, 55.7% were male, median age 45 years. Their main underlying conditions were as follows: prosthetic valve surgery (34.4%) and solid organ transplant (SOT) (19.7%). Mainly affecting mitral (36.1%) and aortic valve (29.5%). Main isolated species were as follows: Aspergillus fumigatus (47.5%) and Aspergillus flavus (24.6%). Embolisms occurred in 54%. Patients were treated with antifungals (90.2%), heart surgery (85.2%) or both (78.7%). Overall, 52.5% died. A greater mortality was observed in immunosuppressed patients (59.4% vs. 24.1%, OR = 4.09, 95%CI = 1.26-13.19, p = .02), and lower mortality was associated with undergoing cardiac surgery plus azole therapy (28.1% vs. 65.5%, OR = 0.22, 95%CI = 0.07-0.72, p = .01). CONCLUSIONS: AE accounts for 0.2% of all IE episodes of a national multicentric cohort, mainly affecting patients with previous valvular surgery or SOT recipients. Mortality remains high especially in immunosuppressed hosts and azole-based treatment combined with surgical resection are related to a better outcome.

Efficacy and safety of Isavuconazole for the treatment of invasive Aspergillus infection - an update of the literature.

INTRODUCTION: Invasive aspergillosis is associated with high morbidity and mortality in immunocompromised patients. It is now increasingly reported in critically ill patients, including those with respiratory viral infections, such as influenza and COVID-19. Antifungal management is challenging due to diagnostic delay, adverse drug reactions, drug-drug interactions, narrow therapeutic window, and the emergence of resistance. Isavuconazole is the most recent FDA approved azole for the treatment of invasive aspergillosis, with data continuing to accumulate. AREAS COVERED: The authors review the safety and efficacy of isavuconazole in the management of invasive aspergillosis based on the currently available evidence. The authors also report on the structure, mechanism of action, pharmacokinetic properties, in vitro and in vivo studies as well as clinical safety and efficacy reports of isavuconazole since its FDA approval. EXPERT OPINION: Isavuconazole is non-inferior to voriconazole and is a safe, effective, and better tolerated option for the treatment of invasive aspergillosis. It offers several advantages over other antifungal agents, including having a better adverse event profile with respect to hepatotoxicity, neuro-visual toxicity, QTc prolongation, as well as a stable pharmacokinetic profile obviating the need for therapeutic drug monitoring. Further studies are needed to evaluate its performance in prophylaxis against invasive aspergillosis as well as in the treatment of aspergillosis in critically ill patients without underlying cancer or transplant.

Navigating the Uncertainties of COVID-19-Associated Aspergillosis: A Comparison With Influenza-Associated Aspergillosis.

Invasive pulmonary aspergillosis (IPA) is increasingly recognized as a life-threatening superinfection of severe respiratory viral infections, such as influenza. The pandemic of Coronavirus Disease 2019 (COVID-19) due to emerging SARS-CoV-2 rose concern about the eventuality of IPA complicating COVID-19 in intensive care unit patients. A variable incidence of such complication has been reported, which can be partly attributed to differences in diagnostic strategy and IPA definitions, and possibly local environmental/epidemiological factors. In this article, we discuss the similarities and differences between influenza-associated pulmonary aspergillosis (IAPA) and COVID-19-associated pulmonary aspergillosis (CAPA). Compared to IAPA, the majority of CAPA cases have been classified as putative rather than proven/probable IPA. Distinct physiopathology of influenza and COVID-19 may explain these discrepancies. Whether CAPA represents a distinct entity is still debatable and many questions remain unanswered, such as its actual incidence, the predisposing role of corticosteroids or immunomodulatory drugs, and the indications for antifungal therapy.

Triple infection with disseminated tuberculosis, invasive aspergillosis and COVID-19 in an organ transplant recipient with iatrogenic immunosuppression.

A 39-year-old man with diabetes mellitus and hypertension presented two years following renal transplantation with evening pyrexia, night sweats and loss of weight. He was diagnosed with disseminated tuberculosis and invasive aspergillosis and commenced on antituberculous and antifungal therapy. Immunosuppressants except for the maintenance dose of steroids were discontinued. Two weeks later, he acquired severe COVID-19 pneumonia complicated with type 1 respiratory failure and haemodynamic instability. He was treated with non-invasive ventilation and inotropic support with a vasopressor-augmenting dose of steroids. Management challenges were diagnosing the respiratory pathologies with limited investigations, deciding on continuation of steroids in an organ transplant recipient with disseminated infection and deciding the ceiling of care in a low-resource setting given the background of multiple pulmonary insults. A multidisciplinary team decided to continue high-dose steroids and escalate to a full ceiling of care. He recovered from COVID-19 pneumonia 15 days following diagnosis and was discharged home. The potential adverse effects of steroids on tuberculosis and aspergillosis are to be monitored during follow-up.

Genomic Diversity of Azole-Resistant Aspergillus fumigatus in the United States.

Azole resistance in pathogenic Aspergillus fumigatus has become a global public health issue threatening the use of medical azoles. The environmentally occurring resistance mutations, TR34/L98H (TR34) and TR46/Y121F/T289A (TR46), are widespread across multiple continents and emerging in the United States. We used whole-genome single nucleotide polymorphism (SNP) analysis on 179 nationally represented clinical and environmental A. fumigatus genomes from the United States along with 18 non-U.S. genomes to evaluate the genetic diversity and foundation of the emergence of azole resistance in the United States. We demonstrated the presence of clades of A. fumigatus isolates: clade A (17%) comprised a global collection of clinical and environmental azole-resistant strains, including all strains with the TR34/L98H allele from India, The Netherlands, the United Kingdom, and the United States, and clade B (83%) consisted of isolates without this marker mainly from the United States. The TR34/L98H polymorphism was shared among azole-resistant A. fumigatus strains from India, The Netherlands, the United Kingdom, and the United States, suggesting the common origin of this resistance mechanism. Six percent of azole-resistant A. fumigatus isolates from the United States with the TR34 resistance marker had a mixture of clade A and clade B alleles, suggestive of recombination. Additionally, the presence of equal proportions of both mating types further suggests the ongoing presence of recombination. This study demonstrates the genetic background for the emergence of azole resistance in the United States, supporting a single introduction and subsequent propagation, possibly through recombination of environmentally driven resistance mutations. IMPORTANCE Aspergillus fumigatus is one of the most common causes of invasive mold infections in patients with immune deficiencies and has also been reported in patients with severe influenza and severe acute respiratory syndrome coronavirus 2 (SARs-CoV-2). Triazole drugs are the first line of therapy for this infection; however, their efficacy has been compromised by the emergence of azole resistance in A. fumigatus, which was proposed to be selected for by exposure to azole fungicides in the environment [P. E. Verweij, E. Snelders, G. H. J. Kema, E. Mellado, et al., Lancet Infect Dis 9:789-795, 2009, https://doi.org/10.1016/S1473-3099(09)70265-8]. Isolates with environmentally driven resistance mutations, TR34/L98H (TR34) and TR46/Y121F/T289A (TR46), have been reported worldwide. Here, we used genomic analysis of a large sample of resistant and susceptible A. fumigatus isolates to demonstrate a single introduction of TR34 in the United States and suggest its ability to spread into the susceptible population is through recombination between resistant and susceptible isolates.

Fatal disseminated aspergillosis in an immunocompetent patient with COVID-19 due to Aspergillus ochraceus.

Aspergillus infection is a well-known complication of severe influenza and severe acute respiratory syndrome coronavirus (SARS-CoV), and these infections have been related with significant morbidity and mortality even when appropriately diagnosed and treated. Recent studies have indicated that SARS-CoV-2 might increase the risk of invasive pulmonary aspergillosis (IPA). Here, we report the first case of Aspergillus ochraceus in a SARS-CoV-2 positive immunocompetent patient, which is complicated by pulmonary and brain infections. Proven IPA is supported by the positive Galactomannan test, culture-positive, and histopathological evidence. The patient did not respond to voriconazole, and liposomal amphotericin B was added to his anti-fungal regimen. Further studies are needed to evaluate the prevalence of IPA in immunocompetent patients infected with SARS-CoV-2. Consequently, testing for the incidence of Aspergillus species in lower respiratory secretions and Galactomannan test of COVID-19 patients with appropriate therapy and targeted anti-fungal therapy based on the primary clinical suspicion of IPA are highly recommended.

Rates of bacterial co-infections and antimicrobial use in COVID-19 patients: a retrospective cohort study in light of antibiotic stewardship.

The coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread worldwide. Bacterial co-infections are associated with unfavourable outcomes in respiratory viral infections; however, microbiological and antibiotic data related to COVID-19 are sparse. Adequate use of antibiotics in line with antibiotic stewardship (ABS) principles is warranted during the pandemic. We performed a retrospective study of clinical and microbiological characteristics of 140 COVID-19 patients admitted between February and April 2020 to a German University hospital, with a focus on bacterial co-infections and antimicrobial therapy. The final date of follow-up was 6 May 2020. Clinical data of 140 COVID-19 patients were recorded: The median age was 63.5 (range 17-99) years; 64% were males. According to the implemented local ABS guidelines, the most commonly used antibiotic regimen was ampicillin/sulbactam (41.5%) with a median duration of 6 (range 1-13) days. Urinary antigen tests for Legionella pneumophila and Streptococcus peumoniae were negative in all cases. In critically ill patients admitted to intensive care units (n = 50), co-infections with Enterobacterales (34.0%) and Aspergillus fumigatus (18.0%) were detected. Blood cultures collected at admission showed a diagnostic yield of 4.2%. Bacterial and fungal co-infections are rare in COVID-19 patients and are mainly prevalent in critically ill patients. Further studies are needed to assess the impact of antimicrobial therapy on therapeutic outcome in COVID-19 patients to prevent antimicrobial overuse. ABS guidelines could help in optimising the management of COVID-19. Investigation of microbial patterns of infectious complications in critically ill COVID-19 patients is also required.

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.