COVID-19 patients share common, corticosteroid-independent features of impaired host immunity to pathogenic molds

Lethal Disseminated Mucorales Infection With Positive Blood Cultures With Purpura Fulminans Complicating Hemophagocytic Lymphohistiocytosis After Chimeric Antigen Receptor T-Cell Therapy

We report a case of fulminant Mucorales fungemia in a heavily immunosuppressed cancer patient with hemophagocytic lymphohistiocytosis following CD70-targeted chimeric antigen receptor T-cell therapy. Although rare, Mucorales can cause true fungemia in a broad spectrum of hosts, with a range of manifestations from isolated fungemia to fungemia being part of widely disseminated, high-burden infection.

Influenza-associated and COVID-19-associated pulmonary aspergillosis in critically ill patients

Influenza-associated pulmonary aspergillosis (IAPA) and COVID-19-associated pulmonary aspergillosis (CAPA) are increasingly recognised as important complications in patients requiring intensive care for severe viral pneumonia. The diagnosis can typically be made in 10-20% of patients with severe influenza or COVID-19, but only when appropriate diagnostic tools are used. Bronchoalveolar lavage sampling for culture, galactomannan testing, and PCR forms the cornerstone of diagnosis, whereas visual examination of the tracheobronchial tract during bronchoscopy is required to detect invasive Aspergillus tracheobronchitis. Azoles are the first-choice antifungal drugs, with liposomal amphotericin B as an alternative in settings where azole resistance is prevalent. Despite antifungal therapy, IAPA and CAPA are associated with poor outcomes, with fatality rates often exceeding 50%. In this Review, we discuss the mechanistic and clinical aspects of IAPA and CAPA. Moreover, we identify crucial knowledge gaps and formulate directions for future research.

Novel antifungals and treatment approaches to tackle resistance and improve outcomes of invasive fungal disease

SUMMARYFungal infections are on the rise, driven by a growing population at risk and climate change. Currently available antifungals include only five classes, and their utility and efficacy in antifungal treatment are limited by one or more of innate or acquired resistance in some fungi, poor penetration into "sequestered" sites, and agent-specific side effect which require frequent patient reassessment and monitoring. Agents with novel mechanisms, favorable pharmacokinetic (PK) profiles including good oral bioavailability, and fungicidal mechanism(s) are urgently needed. Here, we provide a comprehensive review of novel antifungal agents, with both improved known mechanisms of actions and new antifungal classes, currently in clinical development for treating invasive yeast, mold (filamentous fungi), Pneumocystis jirovecii infections, and dimorphic fungi (endemic mycoses). We further focus on inhaled antifungals and the role of immunotherapy in tackling fungal infections, and the specific PK/pharmacodynamic profiles, tissue distributions as well as drug-drug interactions of novel antifungals. Finally, we review antifungal resistance mechanisms, the role of use of antifungal pesticides in agriculture as drivers of drug resistance, and detail detection methods for antifungal resistance.

Lower respiratory tract single-cell RNA sequencing and neutrophil extracellular trap profiling of COVID-19-associated pulmonary aspergillosis: a single centre, retrospective, observational study

BACKGROUND

COVID-19-associated pulmonary aspergillosis (CAPA) is a severe superinfection with the fungus Aspergillus affecting patients who are critically ill with COVID-19. The pathophysiology and the role of neutrophil extracellular traps (NETs) in this infection are largely unknown. We aimed to characterise the immune profile, with a focus on neutrophils and NET concentrations, of critically ill patients with COVID-19, with or without CAPA.

METHODS

We conducted a single-centre, retrospective, observational study in two patient cohorts, both recruited at University Hospitals Leuven, Belgium. We included adults aged 18 years or older who were admitted to the intensive care unit because of COVID-19 between March 31, 2020, and May 18, 2021, and who were included in the previous Contagious trial (NCT04327570). We investigated the immune cellular landscape of CAPA versus COVID-19 only by performing single-cell RNA sequencing (scRNA-seq) on bronchoalveolar lavage fluid. Bronchoalveolar lavage immune cell fractions were compared between patients with CAPA and patients with COVID-19 only. Additionally, we determined lower respiratory tract NET concentrations using biochemical assays in patients aged 18 years and older who were admitted to the intensive care unit because of severe COVID-19 between March 15, 2020, and Dec 31, 2021, for whom bronchoalveolar lavage was available in the hospital biobank. Bronchoalveolar lavage NET concentrations were compared between patients with CAPA and patients with COVID-19 only and integrated with existing data on immune mediators in bronchoalveolar lavage and 90-day mortality.

FINDINGS

We performed scRNA-seq of bronchoalveolar lavage on 43 samples from 39 patients, of whom 36 patients (30 male and six female; 14 with CAPA) were included in downstream analyses. We performed bronchoalveolar lavage NET analyses in 59 patients (46 male and 13 female), of whom 26 had CAPA. By scRNA-seq, patients with CAPA had significantly lower neutrophil fractions than patients with COVID-19 only (16% vs 33%; p=0·0020). The remaining neutrophils in patients with CAPA preferentially followed a hybrid maturation trajectory characterised by expression of genes linked to antigen presentation, with enhanced transcription of antifungal effector pathways. Patients with CAPA also showed depletion of mucosal-associated invariant T cells, reduced T helper 1 and T helper 17 differentiation, and transcriptional defects in specific aspects of antifungal immunity in macrophages and monocytes. We observed increased formation of NETs in patients with CAPA compared with patients with COVID-19 only (DNA complexed with citrullinated histone H3 median 15 898 ng/mL [IQR 4588-86 419] vs 7062 ng/mL [775-14 088]; p=0·042), thereby explaining decreased neutrophil fractions by scRNA-seq. Low bronchoalveolar lavage NET concentrations were associated with increased 90-day mortality in patients with CAPA.

INTERPRETATION

Qualitative and quantitative disturbances in monocyte, macrophage, B-cell, and T-cell populations could predispose patients with severe COVID-19 to develop CAPA. Hybrid neutrophils form a specialised response to CAPA, and an adequate neutrophil response to CAPA is a major determinant for survival in these patients. Therefore, measuring bronchoalveolar lavage NETs could have diagnostic and prognostic value in patients with CAPA. Clinicians should be wary of aspergillosis when using immunomodulatory therapy that might inhibit NETosis to treat patients with severe COVID-19.

FUNDING

Research Foundation Flanders, KU Leuven, UZ Leuven, VIB, the Fundação para a Ciência e a Tecnologia, the European Regional Development Fund, la Caixa Foundation, the Flemish Government, and Horizon 2020.

High Burden of COVID-19-Associated Pulmonary Aspergillosis in Severely Immunocompromised Patients Requiring Mechanical Ventilation

BACKGROUND

Coronavirus disease 2019 (COVID-19)-associated pulmonary aspergillosis (CAPA) is a frequent superinfection in critically ill patients with COVID-19 and is associated with increased mortality rates. The increasing proportion of severely immunocompromised patients with COVID-19 who require mechanical ventilation warrants research into the incidence and impact of CAPA during the vaccination era.

METHODS

We performed a retrospective, monocentric, observational study. We collected data from adult patients with severe COVID-19 requiring mechanical ventilation who were admitted to the intensive care unit (ICU) of University Hospitals Leuven, a tertiary referral center, between 1 March 2020 and 14 November 2022. Probable or proven CAPA was diagnosed according to the 2020 European Confederation for Medical Mycology/International Society for Human and Animal Mycology (ECMM/ISHAM) criteria.

RESULTS

We included 335 patients. Bronchoalveolar lavage sampling was performed in 300 (90%), and CAPA was diagnosed in 112 (33%). The incidence of CAPA was 62% (50 of 81 patients) in European Organisation for Research and Treatment of Cancer (EORTC)/Mycosis Study Group Education and Research Consortium (MSGERC) host factor-positive patients, compared with 24% (62 of 254) in host factor-negative patients. The incidence of CAPA was significantly higher in the vaccination era, increasing from 24% (57 of 241) in patients admitted to the ICU before October 2021 to 59% (55 of 94) in those admitted since then. Both EORTC/MSGERC host factors and ICU admission in the vaccination era were independently associated with CAPA development. CAPA remained an independent risk factor associated with mortality risk during the vaccination era.

CONCLUSIONS

The presence of EORTC/MSGERC host factors for invasive mold disease is associated with increased CAPA incidence and worse outcome parameters, and it is the main driver for the significantly higher incidence of CAPA in the vaccination era. Our findings warrant investigation of antifungal prophylaxis in critically ill patients with COVID-19.

Immune and metabolic perturbations in COVID-19-associated pulmonary mucormycosis: A transcriptome analysis of innate immune cells

BACKGROUND AND OBJECTIVES

The mechanisms underlying COVID-19-associated pulmonary mucormycosis (CAPM) remain unclear. We use a transcriptomic analysis of the innate immune cells to investigate the host immune and metabolic response pathways in patients with CAPM.

PATIENTS AND METHODS

We enrolled subjects with CAPM (n = 5), pulmonary mucormycosis (PM) without COVID-19 (n = 5), COVID-19 (without mucormycosis, n = 5), healthy controls (n = 5) without comorbid illness and negative for SARS-CoV-2. Peripheral blood samples from cases were collected before initiating antifungal therapy, and neutrophils and monocytes were isolated. RNA sequencing was performed using Illumina HiSeqX from monocytes and neutrophils. Raw reads were aligned with HISAT-2 pipeline and DESeq2 was used for differential gene expression. Gene ontology (GO) and metabolic pathway analysis were performed using Shiny GO application and R packages (ggplot2, Pathview).

RESULTS

The derangement of core immune and metabolic responses in CAPM patients was noted. Pattern recognition receptors, dectin-2, MCL, FcRγ receptors and CLEC-2, were upregulated, but signalling pathways such as JAK-STAT, IL-17 and CARD-9 were downregulated; mTOR and MAP-kinase signalling were elevated in monocytes from CAPM patients. The complement receptors, NETosis, and pro-inflammatory responses, such as S100A8/A9, lipocalin and MMP9, were elevated. The major metabolic pathways of glucose metabolism-glycolysis/gluconeogenesis, pentose phosphate pathway, HIF signalling and iron metabolism-ferroptosis were also upregulated in CAPM.

CONCLUSIONS

We identified significant alterations in the metabolic pathways possibly leading to cellular iron overload and a hyperglycaemic state. Immune responses revealed altered recognition, signalling, effector functions and a pro-inflammatory state in monocytes and neutrophils from CAPM patients.

Pathogenicity and virulence of Aspergillus fumigatus

Pulmonary infections caused by the mould pathogen Aspergillus fumigatus are a major cause of morbidity and mortality globally. Compromised lung defences arising from immunosuppression, chronic respiratory conditions or more recently, concomitant viral or bacterial pulmonary infections are recognised risks factors for the development of pulmonary aspergillosis. In this review, we will summarise our current knowledge of the mechanistic basis of pulmonary aspergillosis with a focus on emerging at-risk populations.

Effect of glucocorticoids on the development of COVID-19-associated pulmonary aspergillosis: A meta-analysis of 21 studies and 5174 patients

COVID-19-associated pulmonary aspergillosis (CAPA) remains a high mortality mycotic infection throughout the pandemic, and glucocorticoids (GC) may be its root cause. Our aim was to evaluate the effect of systemic GC treatment on the development of CAPA. We systematically searched the PubMed, Google Scholar, Scopus and Embase databases to collect eligible studies published until 31 December 2022. The pooled outcome of CAPA development was calculated as the log odds ratio (LOR) with 95% confidence intervals (CI) using a random effect model. A total of 21 studies with 5174 patients were included. Of these, 20 studies with 4675 patients consisting of 2565 treated with GC but without other immunomodulators (GC group) and 2110 treated without GC or other immunomodulators (controls) were analysed. The pooled LOR of CAPA development was higher for the GC group than for the controls (0.54; 95% CI: 0.22, 0.86; p < .01). In the subgroups, the pooled LOR was higher for high-dose GC (0.90; 95% CI: 0.17, 1.62: p = .01) and dexamethasone (0.71; 95% CI: 0.35, 1.07; p < .01) but had no significant difference for low-dose GC (0.41; 95% CI: -0.07, 0.89; p = .09), and non-dexamethasone GC (0.21; 95% CI: -0.36, 0.79; p = .47), treated patients versus controls. GC treatment increases the risk of CAPA development, and this risk is particularly associated with the use of high-dose GC or dexamethasone treatment.

Treatment of Invasive Aspergillosis: How It's Going, Where It's Heading

Despite improvements in treatment and diagnostics over the last two decades, invasive aspergillosis (IA) remains a devastating fungal disease. The number of immunocompromised patients and hence vulnerable hosts increases, which is paralleled by the emergence of a rise in IA cases. Increased frequencies of azole-resistant strains are reported from six continents, presenting a new challenge for the therapeutic management. Treatment options for IA currently consist of three classes of antifungals (azoles, polyenes, echinocandins) with distinctive advantages and shortcomings. Especially in settings of difficult to treat IA, comprising drug tolerance/resistance, limiting drug-drug interactions, and/or severe underlying organ dysfunction, novel approaches are urgently needed. Promising new drugs for the treatment of IA are in late-stage clinical development, including olorofim (a dihydroorotate dehydrogenase inhibitor), fosmanogepix (a Gwt1 enzyme inhibitor), ibrexafungerp (a triterpenoid), opelconazole (an azole optimized for inhalation) and rezafungin (an echinocandin with long half-life time). Further, new insights in the pathophysiology of IA yielding immunotherapy as a potential add-on therapy. Current investigations show encouraging results, so far mostly in preclinical settings. In this review we discuss current treatment strategies, give an outlook on possible new pharmaceutical therapeutic options, and, lastly, provide an overview of the ongoing research in immunotherapy for IA.

The Important Role of Interleukin-2 in COVID-19

There is controversial literature about the effects of the interleukin-2 (IL-2) cytokine family in COVID-19 pathogenesis and immunity. So we aimed to identify the potential in the role of the IL-2 family in COVID-19. A narrative review search was done through online databases, including PubMed, Scopus, and Web of Science. The search deadline was up to December 2022. We applied no time limits for the searching strategy. After retrieving articles from the databases, the authors summarized the data into two data extraction tables. The first data extraction table described the changes in the IL-2 cytokine family in COVID-19 and the second table described the therapeutic interventions targeting IL-2 family cytokines. The results of the literature on the role of the IL-2 cytokine family do not show a singular rule. IL-2 cytokine family can change during severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Some studies suggest that IL-2 cytokine family rise during the infection and cause severe inflammatory response and cytokine storm. These cytokines are shown to be increased in immunocompromised patients and worsen their prognosis. In individuals without underlying disease, the upregulation of the IL-2 family shows the clinical outcome of the disease and rises with disease severity. However, some other studies show that these cytokines do not significantly change. IL-2 cytokine family is mostly upregulated in healthy individuals who had vaccination, but immunocompromised patients did not show significant changes after a single dose of vaccines, which shows that these patients need booster doses for efficient immunity. IL-2 cytokine family can also be used as immunotherapy agents in COVID-19.

Relationship between COVID-19 and ICU-Acquired Bloodstream Infections Related to Multidrug-Resistant Bacteria

A bloodstream infection (BSI) is a severe ICU-acquired infection. A growing proportion is caused by multidrug-resistant bacteria (MDRB). COVID-19 was reported to be associated with a high rate of secondary infections. However, there is a lack of data on the relationship between COVID-19 and the incidence of MDRB ICU-acquired BSI. The aim of this study was to evaluate the relationship between COVID-19 and ICU-acquired BSI related to MDRB. This retrospective study was conducted in a single-center ICU during a one-year period. All adult patients admitted for more than 48 h were included. The cumulative incidence of ICU-acquired BSI related to MDRB was estimated using the Kalbfleisch and Prentice method. The association of COVID-19 status with the risk of ICU-acquired BSI related to MDRB was assessed using cause-specific Cox's proportional hazard model. Among the 1320 patients included in the analysis, 497 (37.65%) had COVID-19. ICU-acquired BSI related to MDRB occurred in 50 patients (36 COVID patients (7%) and 14 non-COVID patients (1.6%)). Extended-spectrum beta-lactamase Enterobacteriacae (46%) and carbapenem-resistant Acinetobacter baumannii (30%) were the most commonly isolated MDRB. COVID-19 was significantly associated with a higher risk of MDRB ICU-acquired BSI (adjusted cHR 2.65 (1.25 to 5.59) for the whole study period). However, this relationship was only significant for the period starting at day 15 after ICU admission. ICU-acquired BSI related to MDRB was significantly associated with ICU mortality (HR (95%CI) 1.73 (1-3)), although COVID-19 had no significant impact on this association (p het 0.94). COVID-19 is significantly associated with an increased risk of ICU-acquired BSI related to MDRB, mainly during the period starting at day 15 after ICU admission.

COVID-19-associated pulmonary aspergillosis in immunocompetent patients: a virtual patient cohort study

The opportunistic fungus Aspergillus fumigatus infects the lungs of immunocompromised hosts, including patients undergoing chemotherapy or organ transplantation. More recently however, immunocompetent patients with severe SARS-CoV2 have been reported to be affected by COVID-19 Associated Pulmonary Aspergillosis (CAPA), in the absence of the conventional risk factors for invasive aspergillosis. This paper explores the hypothesis that contributing causes are the destruction of the lung epithelium permitting colonization by opportunistic pathogens. At the same time, the exhaustion of the immune system, characterized by cytokine storms, apoptosis, and depletion of leukocytes may hinder the response to A. fumigatus infection. The combination of these factors may explain the onset of invasive aspergillosis in immunocompetent patients. We used a previously published computational model of the innate immune response to infection with Aspergillus fumigatus. Variation of model parameters was used to create a virtual patient population. A simulation study of this virtual patient population to test potential causes for co-infection in immunocompetent patients. The two most important factors determining the likelihood of CAPA were the inherent virulence of the fungus and the effectiveness of the neutrophil population, as measured by granule half-life and ability to kill fungal cells. Varying these parameters across the virtual patient population generated a realistic distribution of CAPA phenotypes observed in the literature. Computational models are an effective tool for hypothesis generation. Varying model parameters can be used to create a virtual patient population for identifying candidate mechanisms for phenomena observed in actual patient populations.

Targeting the Granulocytic Defense against A. fumigatus in Healthy Volunteers and Septic Patients

Neutrophil granulocytes (NGs) are among the key players in the defense against Aspergillus fumigatus (A. fumigatus). To better elucidate a pathophysiological understanding of their role and functions, we applied a human cell model using NGs from healthy participants and septic patients to evaluate their inhibitory effects on the growth of A. fumigatus ex vivo. Conidia of A. fumigatus (ATCC^® 204305) were co-incubated with NGs from healthy volunteers or septic patients for 16 h. A. fumigatus growth was measured by XTT assays with a plate reader. The inhibitory effect of NGs on 18 healthy volunteers revealed great heterogeneity. Additionally, growth inhibition was significantly stronger in the afternoon than the morning, due to potentially different cortisol levels. It is particularly interesting that the inhibitory effect of NGs was reduced in patients with sepsis compared to healthy controls. In addition, the magnitude of the NG-driven defense against A. fumigatus was highly variable among healthy volunteers. Moreover, daytime and corresponding cortisol levels also seem to have a strong influence. Most interestingly, preliminary experiments with NGs from septic patients point to a strongly diminished granulocytic defense against Aspergillus spp.

Deficient Phagocytosis in Circulating Monocytes from Patients with COVID-19-Associated Mucormycosis

Cases of rhino-orbital mucormycosis in patients suffering from severe coronavirus disease 2019 (COVID-19) were reported in different parts of the world, especially in India. However, specific immune mechanisms that are linked to susceptibility to COVID-19-associated mucormycosis (CAM) remain largely unexplored. We aimed to explore whether the differential regulation of circulating cytokines in CAM patients had any potential pathogenic links with myeloid phagocyte function and susceptibility to mucormycosis. A small cohort of Indian patients suffering from CAM (N = 9) as well as COVID-19 patients with no evidence of mucormycosis (N = 5) were recruited in the study. Venous blood was collected from the patients as well as from healthy volunteers (N = 8). Peripheral blood mononuclear cells and plasma were isolated. Plasma samples were used to measure a panel of 48 cytokines. CD14⁺ monocytes were isolated and used for a flow cytometric phagocytosis assay as well as a global transcriptome analysis via RNA-sequencing. A multiplex cytokine analysis of the plasma samples revealed reduction in a subset of cytokines in CAM patients, which is known to potentiate the activation, migration, or phagocytic activity of myeloid cells, compared to the COVID-19 patients who did not contract mucormycosis. Compared to monocytes from healthy individuals, peripheral blood CD14⁺ monocytes from CAM patients were significantly deficient in phagocytic function. The monocyte transcriptome also revealed that pathways related to endocytic pathways, phagosome maturation, and the cytoskeletal regulation of phagocytosis were significantly downregulated in CAM patients. Thus, the study reports a significant deficiency in the phagocytic activity of monocytes, which is a critical effector mechanism for the antifungal host defense, in patients with CAM. This result is in concordance with results regarding the specific cytokine signature and monocyte transcriptome. IMPORTANCE A number of cases of mucormycosis, often fatal, were reported among severe COVID-19 patients from India as well as from some other parts of the world. However, specific immunocellular mechanisms that underlie susceptibility to this fungal infection in COVID-19 remain largely unexplored. Our study reports a deficiency in phagocytosis by monocytes in COVID-19 patients who are concomitantly afflicted with mucormycosis, with this deficiency being linked to a characteristic monocyte transcriptome as well as a circulating cytokine signature. The functional phenotype and cytokine signature of the monocytes may provide useful biomarkers for detecting potential susceptibility to mucormycosis in COVID-19 as well as in other viral infections.

Surrogate infection model predicts optimal alveolar macrophage number for clearance of Aspergillus fumigatus infections

The immune system has to fight off hundreds of microbial invaders every day, such as the human-pathogenic fungus Aspergillus fumigatus. The fungal conidia can reach the lower respiratory tract, swell and form hyphae within six hours causing life-threatening invasive aspergillosis. Invading pathogens are continuously recognized and eliminated by alveolar macrophages (AM). Their number plays an essential role, but remains controversial with measurements varying by a factor greater than ten for the human lung. We here investigate the impact of the AM number on the clearance of A. fumigatus conidia in humans and mice using analytical and numerical modeling approaches. A three-dimensional to-scale hybrid agent-based model (hABM) of the human and murine alveolus allowed us to simulate millions of virtual infection scenarios, and to gain quantitative insights into the infection dynamics for varying AM numbers and infection doses. Since hABM simulations are computationally expensive, we derived and trained an analytical surrogate infection model on the large dataset of numerical simulations. This enables reducing the number of hABM simulations while still providing (i) accurate and immediate predictions on infection progression, (ii) quantitative hypotheses on the infection dynamics under healthy and immunocompromised conditions, and (iii) optimal AM numbers for combating A. fumigatus infections in humans and mice.

Autoimmunity and Immunodeficiency in Severe SARS-CoV-2 Infection and Prolonged COVID-19

SARS-CoV-2 causes the complex and heterogeneous illness known as COVID-19. The disease primarily affects the respiratory system but can quickly become systemic, harming multiple organs and leading to long-lasting sequelae in some patients. Most infected individuals are asymptomatic or present mild symptoms. Antibodies, complement, and immune cells can efficiently eliminate the virus. However, 20% of individuals develop severe respiratory illness and multiple organ failure. Virus replication has been described in several organs in patients who died from COVID-19, suggesting a compromised immune response. Immunodeficiency and autoimmunity are responsible for this impairment and facilitate viral escape. Mutations in IFN signal transduction and T cell activation are responsible for the inadequate response in young individuals. Autoantibodies are accountable for secondary immunodeficiency in patients with severe infection or prolonged COVID-19. Antibodies against cytokines (interferons α, γ and ω, IL1β, IL6, IL10, IL-17, IL21), chemokines, complement, nuclear proteins and DNA, anticardiolipin, and several extracellular proteins have been reported. The type and titer of autoantibodies depend on age and gender. Organ-specific autoantibodies have been described in prolonged COVID-19. Their role in the disease is under study. Autoimmunity and immunodeficiency should be screened as risk factors for severe or prolonged COVID-19.

COVID-19 associated mold infections: Review of COVID-19 associated pulmonary aspergillosis and mucormycosis

COVID-19-associated mold infection (CAMI) is defined as development of mold infections in COVID-19 patients. Co-pathogenesis of viral and fungal infections include the disruption of tissue barrier following SARS CoV-2 infection with the damage in the alveolar space, respiratory epithelium and endothelium injury and overwhelming inflammation and immune dysregulation during severe COVID-19. Other predisposing risk factors permissive to fungal infections during COVID-19 include the administration of immune modulators such as corticosteroids and IL-6 antagonist. COVID-19-associated pulmonary aspergillosis (CAPA) and COVID-19-associated mucormycosis (CAM) is increasingly reported during the COVID-19 pandemic. CAPA usually developed within the first month of COVID infection, and CAM frequently arose 10-15 days post diagnosis of COVID-19. Diagnosis is challenging and often indistinguishable during the cytokine storm in COVID-19, and several diagnostic criteria have been proposed. Development of CAPA and CAM is associated with a high mortality despiteappropriate anti-mold therapy. Both isavuconazole and amphotericin B can be used for treatment of CAPA and CAM; voriconazole is the primary agent for CAPA and posaconazole is an alternative for CAM. Aggressive surgery is recommended for CAM to improve patient survival. A high index of suspicion and timely and appropriate treatment is crucial to improve patient outcome.

Defective antifungal immunity in patients with COVID-19

The COVID-19 pandemic has placed a huge strain on global healthcare and been a significant cause of increased morbidity and mortality, particularly in at-risk populations. This disease attacks the respiratory systems and causes significant immune dysregulation in affected patients creating a perfect opportunity for the development of invasive fungal disease (IFD). COVID-19 infection can instill a significant, poorly regulated pro-inflammatory response. Clinically induced immunosuppression or pro-inflammatory damage to mucosa facilitate the development of IFD and Aspergillus, Mucorales, and Candida infections have been regularly reported throughout the COVID-19 pandemic. Corticosteroids and immune modulators are used in the treatment of COVID-19. Corticosteroid use is also a risk factor for IFD, but not the only reason for IFD in COVID -19 patients. Specific dysregulation of the immune system through functional exhaustion of Natural killer (NK) cells and T cells has been observed in COVID-19 through the expression of the exhaustion markers NK-G2A and PD-1. Reduced fungicidal activity of neutrophils from COVID-19 patients indicates that immune dysfunction/imbalance are important risk factors for IFD. The COVID-19 pandemic has significantly increased the at-risk population for IFD. Even if the incidence of IFD is relatively low, the size of this new at-risk population will result in a substantial increase in the overall, annual number of IFD cases. It is important to understand how and why certain patients with COVID-19 developed increased susceptibility to IFD, as this will improve our understanding of risk of IFD in the face of future pandemics but also in a clinical era of increased clinical immuno-suppression/modulation.