Bicarbonate correction of ketoacidosis alters host-pathogen interactions and alleviates mucormycosis

Comprehensive Review on the Virulence Factors and Therapeutic Strategies with the Aid of Artificial Intelligence against Mucormycosis

Mucormycosis, a rare but deadly fungal infection, was an epidemic during the COVID-19 pandemic. The rise in cases (COVID-19-associated mucormycosis, CAM) is attributed to excessive steroid and antibiotic use, poor hospital hygiene, and crowded settings. Major contributing factors include diabetes and weakened immune systems. The main manifesting forms of CAM─cutaneous, pulmonary, and the deadliest, rhinocerebral─and disseminated infections elevated mortality rates to 85%. Recent focus lies on small-molecule inhibitors due to their advantages over standard treatments like surgery and liposomal amphotericin B (which carry several long-term adverse effects), offering potential central nervous system penetration, diverse targets, and simpler dosing owing to their small size, rendering the ability to traverse the blood-brain barrier via passive diffusion facilitated by the phospholipid membrane. Adaptation and versatility in mucormycosis are facilitated by a multitude of virulence factors, enabling the pathogen to dynamically respond to various environmental stressors. A comprehensive understanding of these virulence mechanisms is imperative for devising effective therapeutic interventions against this highly opportunistic pathogen that thrives in immunocompromised individuals through its angio-invasive nature. Hence, this Review delineates the principal virulence factors of mucormycosis, the mechanisms it employs to persist in challenging host environments, and the current progress in developing small-molecule inhibitors against them.

Efficacy of an oral lipid nanocrystal formulation of amphotericin B (MAT2203) in the neutropenic mouse model of pulmonary mucormycosis

Invasive mucormycosis (IM) is associated with high mortality and morbidity. MAT2203 is an orally administered lipid nanocrystal formulation of amphotericin B, which has been shown to be safe and effective against other fungal infections. We sought to compare the efficacy of MAT2203 to liposomal amphotericin B (LAMB) treatment in a neutropenic mouse model of IM due to Rhizopus arrhizus var. delemar or Mucor circinelloides f. jenssenii DI15-131. In R. arrhizus var. delemar-infected mice, 15 mg/kg of MAT2203 qd was as effective as 10 mg/kg of LAMB in prolonging median survival time vs placebo (13.5 and 16.5 days for MAT2203 and LAMB, respectively, vs 9 days for placebo) and enhancing overall survival vs placebo-treated mice (40% and 45% for MAT2203 and LAMB, respectively, vs 0% for placebo). A higher dose of 45 mg/kg of MAT2203 was not well tolerated by mice and showed no benefit over placebo. Similar results were obtained with mice infected with M. circinelloides. Furthermore, while both MAT2203 and LAMB treatment resulted in a significant reduction of ~1.0-2.0log and ~2.0-2.5log in Rhizopus delemar or M. circinelloides lung and brain burden vs placebo mice, respectively, LAMB significantly reduced tissue fungal burden in mice infected with R. delemar vs tissues of mice treated with MAT2203. These results support continued investigation and development of MAT2203 as a novel and oral formulation of amphotericin for the treatment of mucormycosis.

Molecular mechanisms that govern infection and antifungal resistance in Mucorales

SUMMARYThe World Health Organization has established a fungal priority pathogens list that includes species critical or highly important to human health. Among them is the order Mucorales, a fungal group comprising at least 39 species responsible for the life-threatening infection known as mucormycosis. Despite the continuous rise in cases and the poor prognosis due to innate resistance to most antifungal drugs used in the clinic, Mucorales has received limited attention, partly because of the difficulties in performing genetic manipulations. The COVID-19 pandemic has further escalated cases, with some patients experiencing the COVID-19-associated mucormycosis, highlighting the urgent need to increase knowledge about these fungi. This review addresses significant challenges in treating the disease, including delayed and poor diagnosis, the lack of accurate global incidence estimation, and the limited treatment options. Furthermore, it focuses on the most recent discoveries regarding the mechanisms and genes involved in the development of the disease, antifungal resistance, and the host defense response. Substantial advancements have been made in identifying key fungal genes responsible for invasion and tissue damage, host receptors exploited by the fungus to invade tissues, and mechanisms of antifungal resistance. This knowledge is expected to pave the way for the development of new antifungals to combat mucormycosis. In addition, we anticipate significant progress in characterizing Mucorales biology, particularly the mechanisms involved in pathogenesis and antifungal resistance, with the possibilities offered by CRISPR-Cas9 technology for genetic manipulation of the previously intractable Mucorales species.

COVID-19 associated mucormycosis surge: A review on multi-pathway mechanisms

Mucormycosis is a fungal infection caused by moulds from the Mucorales order. Concerns have been mounting due to the alarming increase in severe morbidity and mortality associated with mucormycosis during the COVID-19 pandemic. This condition, known as COVID-19-associated mucormycosis (CAM), has been linked to various environmental, host-related, and medical factors on a global scale. We have categorized the most significant potential risk factors for developing mucormycosis in individuals with a previous history of coronavirus infection into 10 major categories. These categories include acute hyperglycemia, the impact of cytokine release, immune response deficiencies in COVID-19 patients, microvasculopathy and dysfunction of endothelial cells, imbalances in iron metabolism, metabolic acidosis, organ damage resulting from COVID-19, underlying health conditions (such as diabetes), environmental factors, and medical treatments that can be iatrogenic in nature (such as inappropriate glucocorticoid use). Many of these factors can lead to potentially life-threatening infections that can complicate the treatment of COVID-19. Physicians should be vigilant about these factors because early detection of mucormycosis is crucial for effective management of this condition.

Efficacy of an oral lipid nanocrystal (LNC) formulation of amphotericin B (MAT2203) in the neutropenic mouse model of pulmonary mucormycosis

Invasive mucormycosis (IM) is associated with high mortality and morbidity and commonly afflicts patients with weakened immune systems. MAT2203 is an orally administered lipid nanocrystal (LNC) formulation of amphotericin B, which has been shown to be safe and effective against other fungal infections. We sought to compare the efficacy of MAT2203 to liposomal amphotericin B (LAMB) treatment in a neutropenic mouse model of IM due to R. arrhizus var. delemar or Mucor circinelloides f. jenssenii DI15-131. Treatment with placebo (diluent control), oral MAT2203 administered as BID and QD or intravenous LAMB for 4 days, began 16 h post infection and continued for 7 and 4 days, respectively. Survival through Day +21 and tissue fungal burden of lung or brain in animals euthanized on Day +4 served as a primary and secondary endpoint, respectively. In both infection types, MAT2203 was as effective as LAMB in prolonging median survival time (MST) and enhancing overall survival vs. placebo-treated mice ( P <0.05 by Log-Rank). Furthermore, both MAT2203 and LAMB treatment resulted in significant ∼1.0-1.5-log reduction and ∼2.0-2.2-log in R. delemar or M. circinelloides lung and brain burden, vs. placebo mice, respectively. These results support the potential efficacy of oral MAT2203 as an alternative to LAMB. Continued investigation and development of this novel oral formulation of the amphotericin B for the treatment of mucormycosis is warranted.

Mucormycosis in 2023: an update on pathogenesis and management

Mucormycosis (MCR) is an emerging and frequently lethal fungal infection caused by the Mucorales family, with Rhizopus, Mucor, and Lichtheimia, accounting for > 90% of all cases. MCR is seen in patients with severe immunosuppression such as those with hematologic malignancy or transplantation, Diabetes Mellitus (DM) and diabetic ketoacidosis (DKA) and immunocompetent patients with severe wounds. The recent SARS COV2 epidemy in India has resulted in a tremendous increase in MCR cases, typically seen in the setting of uncontrolled DM and corticosteroid use. In addition to the diversity of affected hosts, MCR has pleiotropic clinical presentations, with rhino-orbital/rhino-cerebral, sino-pulmonary and necrotizing cutaneous forms being the predominant manifestations. Major insights in MCR pathogenesis have brought into focus the host receptors (GRP78) and signaling pathways (EGFR activation cascade) as well as the adhesins used by Mucorales for invasion. Furthermore, studies have expanded on the importance of iron availability and the complex regulation of iron homeostasis, as well as the pivotal role of mycotoxins as key factors for tissue invasion. The molecular toolbox to study Mucorales pathogenesis remains underdeveloped, but promise is brought by RNAi and CRISPR/Cas9 approaches. Important recent advancements have been made in early, culture-independent molecular diagnosis of MCR. However, development of new potent antifungals against Mucorales remains an unmet need. Therapy of MCR is multidisciplinary and requires a high index of suspicion for initiation of early Mucorales-active antifungals. Reversal of underlying immunosuppression, if feasible, rapid DKA correction and in selected patients, surgical debulking are crucial for improved outcomes.

Immune responses to human fungal pathogens and therapeutic prospects

Pathogenic fungi have emerged as significant causes of infectious morbidity and death in patients with acquired immunodeficiency conditions such as HIV/AIDS and following receipt of chemotherapy, immunosuppressive agents or targeted biologics for neoplastic or autoimmune diseases, or transplants for end organ failure. Furthermore, in recent years, the spread of multidrug-resistant Candida auris has caused life-threatening outbreaks in health-care facilities worldwide and raised serious concerns for global public health. Rapid progress in the discovery and functional characterization of inborn errors of immunity that predispose to fungal disease and the development of clinically relevant animal models have enhanced our understanding of fungal recognition and effector pathways and adaptive immune responses. In this Review, we synthesize our current understanding of the cellular and molecular determinants of mammalian antifungal immunity, focusing on observations that show promise for informing risk stratification, prognosis, prophylaxis and therapies to combat life-threatening fungal infections in vulnerable patient populations.

Secondary fungal infections in SARS-CoV-2 patients: pathological whereabouts, cautionary measures, and steadfast treatments

The earliest documented COVID-19 case caused by the SARS-CoV-2 coronavirus occurred in Wuhan, China, in December 2019. Since then, several SARS-CoV-2 mutants have rapidly disseminated as exemplified by the community spread of the recent omicron variant. The disease already attained a pandemic status with ever-dwindling mortality even after two and half years of identification and considerable vaccination. Aspergillosis, candidiasis, cryptococcosis and mucormycosis are the prominent fungal infections experienced by the majority of SARS-CoV-2 high-risk patients. In its entirety, COVID-19's nexus with these fungal infections may worsen the intricacies in the already beleaguered high-risk patients, making this a topic of substantial clinical concern. Thus, thorough knowledge of the subject is necessary. This article focuses on the concomitant fungal infection(s) in COVID-19 patients, taking into account their underlying causes, the screening methods, manifested drug resistance, and long-term effects. The information and knowledge shared herein could be crucial for the management of critically ill, aged, and immunocompromised SARS-CoV-2 patients who have had secondary fungal infections (SFIs).

Mucorales and Mucormycosis: Recent Insights and Future Prospects

The classification of Mucorales encompasses a collection of basal fungi that have traditionally demonstrated an aversion to modern genetic manipulation techniques. This aversion led to a scarcity of knowledge regarding their biology compared to other fungal groups. However, the emergence of mucormycosis, a fungal disease caused by Mucorales, has attracted the attention of the clinical field, mainly because available therapies are ineffective for decreasing the fatal outcome associated with the disease. This revitalized curiosity about Mucorales and mucormycosis, also encouraged by the recent COVID-19 pandemic, has spurred a significant and productive effort to uncover their mysteries in recent years. Here, we elaborate on the most remarkable breakthroughs related to the recently discovered genetic advances in Mucorales and mucormycosis. The utilization of a few genetic study models has enabled the identification of virulence factors in Mucorales that were previously described in other pathogens. More notably, recent investigations have identified novel genes and mechanisms controlling the pathogenic potential of Mucorales and their interactions with the host, providing fresh avenues to devise new strategies against mucormycosis. Finally, new study models are allowing virulence studies that were previously hampered in Mucorales, predicting a prolific future for the field.

Local Administration of Sodium Bicarbonate for Preventing COVID-19 Associated Mucormycosis

Background

One important complication of the coronavirus disease 2019 (COVID-19) is COVID Associated Mucormycosis (CAM), especially in patients with conditions such as diabetes and in immunosuppressed patients. Systemic acidosis, hyperglycemia, and other biochemical factors such as free iron and β-hydroxybutyrate (BHB) can play a role in this complication.

Materials and Methods

Rhizopus oryzae was isolated from a patient at Masih Daneshvari Hospital microbiology laboratory and sub-cultured on the Potato Dextrose Agar (PDA) for 48 hours at 37 °C. Subsequently, Roswell Park Memorial Institute (RPMI) 1640 Broth medium buffered to pH 7.0 with 3-N-morpholino-propane sulfonic acid. Macrodilution and microdilution methods were performed with 8.4% sodium bicarbonate. After 24 hours of incubation at 35°C, the minimum inhibitory concentration (MIC) and the minimum fungicidal concentrations (MFC) were evaluated.

Results

We found that the minimum inhibitory and fungicidal concentrations are at 1.05 % and 2.1 % respectively. Therefore, the minimum concentration is 2% sodium bicarbonate, which requires achieving the desired environmental pH for fungal inhibition and fungicidal effects.

Conclusion

Regulation of systemic acidosis by sodium bicarbonate could be used to decrease the chance of mucormycosis. In addition, According to our study and some others, an alkaline environment can prevent fungal growth. We found that a minimum concentration of 2% sodium bicarbonate is required to achieve the desired mucosal pH to inhibit the fungus. Therefore, sodium bicarbonate inhalation, as a cost-effective and well-tolerated medicine, is a good candidate for the prevention of mucormycosis. In this regard, extensive clinical and laboratory research is needed to achieve more accurate doses and appropriate administration intervals.

Perturbations of immune landscape in COVID-19 associated mucormycosis

BACKGROUND

A rise in secondary fungal infections during the COVID-19 pandemic necessitates a deeper understanding of the associated immunological perturbations.

OBJECTIVES

To evaluate the clinical and immunological characteristics observed in patients with COVID-19 associated mucormycosis (CAM) infection.

PATIENTS/ METHODS

Cases of mucormycosis with or post-COVID-19 infection were compared with cases of acute COVID-19 and convalescent COVID-19. Lymphocyte subsets, cytokines and other laboratory markers were compared between the groups.

RESULTS

The frequency of proposed risk factors for CAM was diabetes mellitus (77%), recent history of steroid use (69%) and hypoxia during COVID-19 infection (52%). Iron metabolism was dysregulated in CAM patients with low TIBC and total iron. Further, CAM was accompanied with lymphopenia with drastic reduction in B cell counts; however, plasmablasts were not altered. Further, CAM patients had low immunoglobulin levels and antibodies specific to mucor peptide did not increase in CAM suggesting dysfunction in B-cell response. There was increase in activated effector cytotoxic CD8 T cells and NK cells in CAM compared with COVID-19 infection and healthy controls. Among T helper cells, Tregs were reduced and Th-1 frequency was increased in CAM compared with COVID-19 infection. A distinct cytokine signature was evident in CAM with increase in IL-1β, IFN-γ, IL-6, IL-22, IL-17A, IL-10, IL-2, IL-8, IL-7, IL-21 and GM-CSF.

CONCLUSION

This is the first study on immunophenotyping in CAM suggesting the need for long-term monitoring of B-cell function after SARS-CoV-2 in patients with dysregulated glycaemic control and the possible benefit of therapeutic supplementation with intravenous immunoglobulins in CAM.

Surge of mucormycosis during the COVID-19 pandemic

Patients with respiratory viral infections are more likely to develop co-infections leading to increased fatality. Mucormycosis is an epidemic amidst the COVID-19 pandemic that conveys a 'double threat' to the global health fraternity. Mucormycosis is caused by the Mucorales group of fungi and exhibits acute angioinvasion generally in immunocompromised patients. The most familiar foci of infections are sinuses (39%), lungs (24%), and skin tissues (19%) where the overall dissemination occurs in 23% of cases. The mortality rate in the case of disseminated mucormycosis is found to be 96%. Symptoms are mostly nonspecific and often resemble other common bacterial or fungal infections. Currently, COVID-19-associated mucormycosis (CAM) is being reported from a number of countries such as the USA, Turkey, France, Mexico, Iran, Austria, UK, Brazil, and Italy, while India is the hotspot for this deadly co-infection, accounting for approximately 28,252 cases up to June 8, 2021. It strikes patients within 12-18 days after COVID-19 recovery, and nearly 80% require surgery. Nevertheless, the mortality rate can reach 94% if the diagnosis is delayed or remains untreated. Sometimes COVID-19 is the sole predisposing factor for CAM. Therefore, this study may provide a comprehensive resource for clinicians and researchers dealing with fungal infections, intending to link the potential translational knowledge and prospective therapeutic challenges to counter this opportunistic pathogen.

A rare case of pediatric gastrointestinal mucormycosis with a review of the literature

This manuscript discusses a rare case of pediatric gastrointestinal mucormycosis in a hospitalized patient who presented in diabetic ketoacidosis. A review of the literature is summarized to provide an overview of mucormycosis with a discussion of the mechanisms underlying the susceptibility of diabetic patients for this condition.

Impact of Hyperglycemia and Diabetes Mellitus on Breakthrough Mucormycosis Outcomes in Patients with Hematologic Malignancies-Complex and Intriguing Associations

Mucormycosis (MCR) is frequently associated with diabetic ketoacidosis and hyperglycemia, as well as hematologic malignancies (HMs) and hematopoietic stem cell transplantation (HSCT). However, little is known about the effect of hyperglycemia on MCR outcomes in patients with HMs. We therefore conducted a retrospective cohort study of adult patients hospitalized with MCR and HM or HSCT (n = 103) at MD Anderson Cancer Center from April 2000 through to April 2020. Twenty-three patients (22%) had documented episodes of severe hyperglycemia. Sixty patients had >5 serum glucose measurements within 28 days prior to MCR symptom onset; of those, 14 (23%) met the criteria for persistent hyperglycemia. Sixteen patients (16%) received insulin prior to admission. The crude mortality 42 days from the onset of MCR symptoms in our cohort was 31%. Neither severe nor persistent hyperglycemia were associated with excess mortality. Insulin use prior to index admission was associated with decreased 42-day mortality on univariate analysis (p = 0.031). In conclusion, in a setting of high crude mortality, severe and/or persistent hyperglycemia do not appear to be associated with excess mortality in patients with HM or HSCT developing MCR. Insulin use prior to MCR diagnosis may be associated with decreased mortality, although further research is needed to validate this effect and to study its mechanistic underpinnings.

Mucormycosis an added burden to Covid-19 Patients: An in-depth systematic review

As of 25th July, 2022, global Disease burden of 575,430,244 confirmed cases and over 6,403,511 deaths have been attributed to coronavirus disease 2019 (COVID-19). Co-infections/secondary infections continue to plague patients around the world as result of the co-morbidities like diabetes mellitus, biochemical changes caused by Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) especially significant elevation in free iron levels, immune suppression caused by SARS-CoV-2, and indiscriminate use of systemic corticosteroids for the treatment of severe COVID-19 disease. In such circumstances, opportunistic fungal infections pose significant challenge for COVID-19 disease therapy in patients with other co-morbidities. Although COVID-19-associated Mucormycosis (CAM) has been widely recognized, currently extensive research is being conducted on mucormycosis. It has been widely agreed that patients undergoing corticosteroid therapy are highly susceptible for CAM, henceforth high index of screening and intensive care and management is need of an hour in order to have favorable outcomes in these patients. Diagnosis in such cases is often delayed and eventually the disease progresses quickly which poses added burden to clinician and increases patient load in critical care units of hospitals. A vast perusal of literature indicated that patients with diabetes mellitus and those with other co-morbidities might be highly vulnerable to develop mucormycosis. In the present work, the case series of three patients presented at Chest Disease Hospital Srinagar, Jammu and Kashmir infected with CAM has been described with their epidemiological data in supplementary section. All these cases were found to be affected with co-morbidity of Diabetes Mellitus (DM) and were under corticosteroid therapy. Furthermore, given the significant death rate linked with mucormycosis and the growing understanding of the diseases significance, systematic review of the literature on CAM has been discussed and we have attempted to discuss emerging CAM and related aspects of the disease.

Diabetic ketoacidosis and coronavirus disease 2019-associated mucormycosis: a case report

Background

Mucormycosis is a rare, life-threatening fungal infection that affects immunocompromised hosts. Diabetes mellitus is a common predisposing condition and most often presents with rhino-orbital-cerebral infection. Association with coronavirus disease 2019 infection was revealed following a resurgence in cases of mucormycosis during the second wave of the pandemic wherein poorly controlled diabetes mellitus was the most significant risk factor in the affected population. Rhino-orbital-cerebral mucormycosis has a high mortality rate, and cerebral involvement is a poor prognostic factor. Herein, we report a case of newly diagnosed diabetes mellitus with concurrent coronavirus disease 2019 infection complicated by diabetic ketoacidosis and rhinocerebral mucormycosis at presentation, describe the diagnostic and therapeutic challenges, and discuss the interventions that ultimately resulted in a favorable clinical response.

Case presentation

We describe the case of a previously healthy 13-year-old African American female patient with newly diagnosed diabetes mellitus and concurrent severe acute respiratory syndrome coronavirus 2 infection whose disease course was complicated by rhinocerebral mucormycosis. She presented with fever, altered mental status, and Kussmaul respirations and was diagnosed with diabetic ketoacidosis with concern for cerebral edema. Concern for infectious cerebritis arose due to recurring fevers and persistently altered mental status despite correction of her metabolic derangements. This raised concern for infectious cerebritis and prompted evaluation with serial head imaging, lumbar puncture, and initiation of broad empiric antimicrobial regimen. Head imaging revealed an evolving cerebral abscess, and fungal deoxyribonucleic acid was identified on blood metagenomics testing, which ultimately confirmed the diagnosis of rhinocerebral mucormycosis. Treatment was challenging as she required surgical debridement of the frontal lobe and aggressive antifungal therapy complicated by electrolyte derangements and electrocardiogram changes that necessitated modification of the antimicrobial regimen. Despite these challenges and high mortality rate, the patient was discharged from the hospital in stable condition to inpatient rehabilitation service for reconditioning after prolonged hospitalization.

Conclusion

Rhinocerebral mucormycosis mortality is associated with delays in therapeutic interventions, thus a high index of suspicion and early recognition were essential for timely initiation of antifungal therapy and surgical debridement.

Invasive Fungal Infections in Dengue Recovered Patients: A New Phenomenon in the Covid-19 Era

Invasive fungal rhinosinusitis was seen to rise to epidemic levels after the 2nd wave of ongoing Covid pandemic, especially in tropical countries, maximally in India. A similar trend is being observed for cases who have recently recovered from dengue virus infection. Post dengue invasive fungal infection is a new presentation and any associations between it and Covid pandemic need to be studied in detail to help prepare for any complications. 3 patients presented to the out-patient department of E.N.T at a tertiary level teaching hospital in East India with complains similar to rhinosinusitis. These patients were then evaluated and diagnosed to be infected from Mucormycosis and Aspergillosis fungal sinusitis after which they were managed with surgical debridement and systemic antifungal therapy. All had a recent history of recovery from Dengue virus infection and a possible association could be suspected. 3 patients presented with complains of pain over upper jaw with orbital swelling and loss of vision developing over a period of 24 days. Two of them had ulceration of hard palate. They were then subjected to Contrast MRI along with CT scan of the Paranasal sinuses which depicted pansinus involvement with intracranial extension in two patients. These were then planned for diagnostic nasal endoscopies along with biopsies which turned out to be Invasive fungal sinusitis in the form of Aspergillosis and Mucormycosis. All the 3 patients had recent history of recovery from Dengue virus infection and did not have any other co-morbidities. Covid Associated Mucormycosis (CAM) is a well-known entity now but no reports of Dengue associated Invasive fungal sinusitis are yet reported. Whether this new phenomenon has anything to do with the interactions between dengue virus and coronavirus is not known at present and needs to be studied in detail so appropriate management protocols can be formulated.

Diabetes mellitus and other underlying conditions in patients with coronavirus disease 2019 associated rhino-orbito-cerebral mucormycosis: a systematic review and meta-analysis

OBJECTIVE

This study aimed to compute the pooled prevalence of diabetes mellitus and other underlying conditions in patients with coronavirus disease 2019 associated rhino-orbito-cerebral mucormycosis.

METHOD

A systematic literature review was performed in PubMed, Scopus, Web of Science, Embase and Google Scholar. The cross-sectional studies that reported the frequency of diabetes mellitus in patients with coronavirus disease 2019 associated rhino-orbito-cerebral mucormycosis were included.

RESULTS

Eighteen eligible studies with a total number of 3718 patients were included in the current study. The pooled prevalence of diabetes in patients with coronavirus disease 2019 associated rhino-orbito-cerebral mucormycosis was 89 per cent and with new-onset diabetes was 32 per cent. The pooled prevalence of steroid use was high (79 per cent) too. The all-cause mortality rate was 24 per cent.

CONCLUSION

Diabetes mellitus was the most frequent underlying condition in patients with coronavirus disease 2019 associated rhino-orbito-cerebral mucormycosis. The second most frequent underlying condition was steroid use during coronavirus disease 2019 infection. The appropriate control of hyperglycaemia and rational prescription of steroids during the treatment of coronavirus disease 2019 associated rhino-orbito-cerebral mucormycosis is recommended.

COVID-19-associated fungal infections

Coronavirus disease 2019 (COVID-19)-associated invasive fungal infections are an important complication in a substantial number of critically ill, hospitalized patients with COVID-19. Three groups of fungal pathogens cause co-infections in COVID-19: Aspergillus, Mucorales and Candida species, including Candida auris. Here we review the incidence of COVID-19-associated invasive fungal infections caused by these fungi in low-, middle- and high-income countries. By evaluating the epidemiology, clinical risk factors, predisposing features of the host environment and immunological mechanisms that underlie the pathogenesis of these co-infections, we set the scene for future research and development of clinical guidance.

Hoenigl and colleagues review the epidemiology, immunology and clinical risk factors contributing to COVID-19-associated fungal infections.

Mucormycosis in the COVID-19 Environment: A Multifaceted Complication

The second wave of coronavirus disease 2019 (COVID-19) caused severe infections with high mortality. An increase in the cases of COVID-19-associated mucormycosis (CAM) was reported predominantly in India. Commonly present in immunocompromised individuals, mucormycosis is often a life-threatening condition. Confounding factors and molecular mechanisms associated with CAM are still not well understood, and there is a need for careful research in this direction. In this review, a brief account of the diagnosis, management, and advancement in drug discovery for mucormycosis has been provided. Here, we summarize major factors that dictate the occurrence of mucormycosis in COVID-19 patients through the analysis of published literature and case reports. Major predisposing factors to mucormycosis appear to be uncontrolled diabetes, steroid therapy, and certain cancers. At the molecular level, increased levels of iron in COVID-19 might contribute to mucormycosis. We have also discussed the potential role and regulation of iron metabolism in COVID-19 patients in establishing fungal growth. Other factors including diabetes prevalence and fungal spore burden in India as contributing factors have also been discussed.

A Novel Prognostic Signature Based on Glioma Essential Ferroptosis-Related Genes Predicts Clinical Outcomes and Indicates Treatment in Glioma

Background

Ferroptosis is a form of programmed cell death (PCD) that has been implicated in cancer progression, although the specific mechanism is not known. Here, we used the latest DepMap release CRISPR data to identify the essential ferroptosis-related genes (FRGs) in glioma and their role in patient outcomes.

Methods

RNA-seq and clinical information on glioma cases were obtained from the Chinese Glioma Genome Atlas (CGGA) and The Cancer Genome Atlas (TCGA). FRGs were obtained from the FerrDb database. CRISPR-screened essential genes (CSEGs) in glioma cell lines were downloaded from the DepMap portal. A series of bioinformatic and machine learning approaches were combined to establish FRG signatures to predict overall survival (OS) in glioma patients. In addition, pathways analysis was used to identify the functional roles of FRGs. Somatic mutation, immune cell infiltration, and immune checkpoint gene expression were analyzed within the risk subgroups. Finally, compounds for reversing high-risk gene signatures were predicted using the GDSC and L1000 datasets.

Results

Seven FRGs (ISCU, NFS1, MTOR, EIF2S1, HSPA5, AURKA, RPL8) were included in the model and the model was found to have good prognostic value (p < 0.001) in both training and validation groups. The risk score was found to be an independent prognostic factor and the model had good efficacy. Subgroup analysis using clinical parameters demonstrated the general applicability of the model. The nomogram indicated that the model could effectively predict 12-, 36-, and 60-months OS and progression-free interval (PFI). The results showed the presence of more aggressive phenotypes (lower numbers of IDH mutations, higher numbers of EGFR and PTEN mutations, greater infiltration of immune suppressive cells, and higher expression of immune checkpoint inhibitors) in the high-risk group. The signaling pathways enriched closely related to the cell cycle and DNA damage repair. Drug predictions showed that patients with higher risk scores may benefit from treatment with RTK pathway inhibitors, including compounds that inhibit RTKs directly or indirectly by targeting downstream PI3K or MAPK pathways.

Conclusion

In summary, the proposed cancer essential FRG signature predicts survival and treatment response in glioma.

Mucormycosis and COVID-19-Associated Mucormycosis: Insights of a Deadly but Neglected Mycosis

The ongoing COVID-19 pandemic has quickly become a health threat worldwide, with high mortality and morbidity among patients with comorbidities. This viral infection promotes the perfect setting in patients for the development of opportunistic infections, such as those caused by fungi. Mucormycosis, a rare but deadly fungal infection, has recently increased its incidence, especially in endemic areas, since the onset of the pandemic. COVID-19-associated mucormycosis is an important complication of the pandemic because it is a mycosis hard to diagnose and treat, causing concern among COVID-19-infected patients and even in the already recovered population. The risk factors for the development of mucormycosis in these patients are related to the damage caused by the SARS-CoV-2 itself, the patient’s overstimulated immune response, and the therapy used to treat COVID-19, causing alterations such as hyperglycemia, acidosis, endothelial and lung damage, and immunosuppression. In this review, the molecular aspects of mucormycosis and the main risk factors for the development of COVID-19-associated mucormycosis are explained to understand this virus–fungi–host interaction and highlight the importance of this neglected mycosis.

COVID-19 associated mucormycosis - An emerging threat

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) rapidly become a global threaten since its emergence in the end of 2019. Moreover, SARS-CoV-2 infection could also present with co-infection or secondary infection by other virus, bacteria, or fungi. Among them, mucormycosis is a rare but aggressive fungal disease and it mainly affects patients particularly with poorly controlled diabetes mellitus with diabetic ketoacidosis (DKA). We here did a comprehensive review of literature reporting COVID-19 associated with mucormycosis (CAM) cases, which have been reported worldwide. The prevalence is higher in India, Iran, and Egypt than other countries, particularly highest in the states of Gujarat and Maharashtra in India. Poor diabetic control and the administration of systemic corticosteroids are the common precipitating factors causing mucormycosis in the severe and critical COVID-19 patients. In addition, COVID-19 itself may affect the immune system resulting in vulnerability of the patients to mucormycosis. Appropriate treatments of CAM include strict glycemic control, extensive surgical debridement, and antifungal therapy with amphotericin B formulations.

Mucormycosis (black fungus) ensuing COVID-19 and comorbidity meets - Magnifying global pandemic grieve and catastrophe begins

Post COVID-19, mucormycosis occurred after the SARS-CoV-2 has rampaged the human population and is a scorching problem among the pandemic globally, particularly among Asian countries. Invasive mucormycosis has been extensively reported from mild to severe COVID-19 survivors. The robust predisposing factor seems to be uncontrolled diabetes mellitus, comorbidity and immunosuppression acquired through steroid therapy. The prime susceptive reason for the increase of mucormycosis cases is elevated iron levels in the serum of the COVID survivors. A panoramic understanding of the infection has been elucidated based on clinical manifestation, genetic and non- genetic mechanisms of steroid drug administration, biochemical pathways and immune modulated receptor associations. This review lime-lights and addresses the "What", "Why", "How" and "When" about the COVID-19 associated mucormycosis (CAM) in a comprehensive manner with a pure intention to bring about awareness to the common public as the cases are inevitably and exponentially increasing in India and global countries as well. The article also unearthed the pathogenesis of mucormycosis and its association with the COVID-19 sequela, the plausible routes of entry, diagnosis and counter remedies to keep the infection at bay. Cohorts of case reports were analysed to spotlight the link between the pandemic COVID-19 and the nightmare-mucormycosis.

Mucormycosis Amid COVID-19 Crisis: Pathogenesis, Diagnosis, and Novel Treatment Strategies to Combat the Spread

The havoc unleashed by COVID-19 pandemic has paved way for secondary ominous fungal infections like Mucormycosis. It is caused by a class of opportunistic pathogens from the order Mucorales. Fatality rates due to this contagious infection are extremely high. Numerous clinical manifestations result in damage to multiple organs subject to the patient's underlying condition. Lack of a proper detection method and reliable treatment has made the management of this infection troublesome. Several reports studying the behavior pattern of Mucorales inside the host by modulation of its defense mechanisms have helped in understanding the pathogenesis of this angio-invasive infection. Many recent advances in diagnosis and treatment of this fungal infection have not been much beneficial. Therefore, there is a need to foster more viable strategies. This article summarizes current and imminent approaches that could aid effective management of these secondary infections in these times of global pandemic. It is foreseen that the development of newer antifungal drugs, antimicrobial peptides, and nanotechnology-based approaches for drug delivery would help combat this infection and curb its spread.

Mucormycosis: A new threat to Coronavirus disease 2019 with special emphasis on India

The main reason for the growth of mucormycosis in people with Coronavirus disease-2019 (COVID-19) is mainly produced by Rhizopus spp. The infective mechanisms and issues recognized in Rhizopus spp. are the cell wall, germination proteins, and enzymes assisted to iron sequestration, CotH protein, and positive regulation of the GRP78 cell receptor. Mucormycosis is mainly caused by the Rhizopus spp. such as R. oryzae, R. microsporus, R. arrhizus, R. homothallicus, etc. that are gifted to numerous host defense mechanisms and attribute to the endothelium via specific receptors, GRP78 simplifying their endocytosis and angio-invasion. Factors such as hyperglycemia, elevated iron concentrations, and ketoacidosis have been shown to contribute to the pathogenesis in the tentative situation. The analytical data of 'black fungus disease' or 'mucormycosis', specify India reported for about 42.3% of published cases, followed by the USA about 16.9%, Iraq, Bangladesh, Iran, Paraguay, and 1 case each from Brazil, Mexico, Italy, UK, China, France, Uruguay, Turkey, and Austria. The COVID-19 infection is maybe a predisposing factor for mucormycosis and is related to a high mortality rate. Early recognition and restriction of hyperglycemia, liposomal amphotericin B, and surgical debridement are the bases in the successful managing of mucormycosis.

The Past, Present and Future of COVID-19 Associated Mucormycosis: A Rapid Review

Coronavirus disease 2019 (COVID-19) is caused by SARS-CoV-2, which is known for the multiple mutations and forms that have rapidly spread across the world. With the imminent challenges faced by low- and middle-income countries in curbing the public health fallbacks due to limited resources, mucormycosis emerged as a fungal infection associated with high mortality. In this rapid review, we explored MEDLINE, Cochrane, Web of Science, WHO Global Database, and the search engine—Google Scholar for articles listed until July 2021 and presented a narrative synthesis of findings from 39 articles. The epidemiology, causative factors, incidence parameters, pharmacological treatment, and recommendations for low- and middle-income countries are enlisted. This study concludes that a majority of the globally reported COVID-19 associated mucormycosis cases stemmed from India. Individuals receiving systemic corticosteroids or who have a history of diabetes mellitus are more prone to contracting the disease. Public health authorities in LMIC are recommended to strengthen antifungal therapies for COVID-19 associated mucormycosis and to strategize reduction in diabetes mellitus prevalence.

Dental and Oral Manifestations of COVID-19 Related Mucormycosis: Diagnoses, Management Strategies and Outcomes

It has been nearly two years since the pandemic caused by the novel coronavirus disease (COVID-19) has affected the world. Several innovations and discoveries related to COVID-19 are surfacing every day and new problems associated with the COVID-19 virus are also coming to light. A similar situation is with the emergence of deep invasive fungal infections associated with severe acute respiratory syndrome 2 (SARS-CoV-2). Recent literature reported the cases of pulmonary and rhino-cerebral fungal infections appearing in patients previously infected by COVID-19. Histopathological analysis of these cases has shown that most of such infections are diagnosed as mucormycosis or aspergillosis. Rhino-orbital-cerebral mucormycosis usually affects the maxillary sinus with involvement of maxillary teeth, orbits, and ethmoidal sinuses. Diabetes mellitus is an independent risk factor for both COVID-19 as well as mucormycosis. At this point, there is scanty data on the subject and most of the published literature comprises of either case reports or case series with no long-term data available. The aim of this review paper is to present the characteristics of COVID-19 related mucormycosis and associated clinical features, outcome, diagnostic and management strategies. A prompt diagnosis and aggressive treatment planning can surely benefit these patients.

Consensus guidelines for the diagnosis and management of invasive fungal disease due to moulds other than Aspergillus in the haematology/oncology setting, 2021

Invasive fungal disease (IFD) due to moulds other than Aspergillus is a significant cause of mortality in patients with malignancies or post haemopoietic stem cell transplantation. The current guidelines focus on the diagnosis and management of the common non-Aspergillus moulds (NAM), such as Mucorales, Scedosporium species (spp.), Lomentospora prolificans and Fusarium spp. Rare but emerging NAM including Paecilomyces variotii, Purpureocillium lilacinum and Scopulariopsis spp. are also reviewed. Culture and histological examination of tissue biopsy specimens remain the mainstay of diagnosis, but molecular methods are increasingly being used. As NAM frequently disseminate, blood cultures and skin examination with biopsy of any suspicious lesions are critically important. Treatment requires a multidisciplinary approach with surgical debridement as a central component. Other management strategies include control of the underlying disease/predisposing factors, augmentation of the host response and the reduction of immunosuppression. Carefully selected antifungal therapy, guided by susceptibility testing, is critical to cure. We also outline novel antifungal agents still in clinical trial which offer substantial potential for improved outcomes in the future. Paediatric recommendations follow those of adults. Ongoing epidemiological research, improvement in diagnostics and the development of new antifungal agents will continue to improve the poor outcomes that have been traditionally associated with IFD due to NAM.

Epidemiology and Pathophysiology of COVID-19-Associated Mucormycosis: India Versus the Rest of the World

The coronavirus disease 2019 (COVID-19) pandemic has led to a concerning resurgence of mucormycosis. More than 47,000 cases of mucormycosis were reported in three months from India. We update our systematic review on COVID-19-associated mucormycosis (CAM) till June 21st, 2021, comparing cases reported from India and elsewhere. We included individual patient details of 275 cases of CAM, of which 233 were reported from India and 42 from the rest of the world. Diabetes mellitus was the most common underlying risk factor for CAM in India than in other countries. The fatality rate of cases reported from India (36.5%) was less than the globally reported cases (61.9%), probably due to the predominance of rhino-orbital mucormycosis. On a multivariate analysis, we found that pulmonary or disseminated mucormycosis cases and admission to the intensive care unit were associated with increased mortality, while combination medical therapy improved survival. The paucity of pulmonary and disseminated mucormycosis cases from India suggests that these cases were either not diagnosed or reported, further supported by a trend of search data from the Google search engine. In this review, we discuss the factors explaining the substantial rise in cases of CAM. We also propose a hypothetical model describing the epidemiologic triad of CAM.

Mucormycosis: A deadly black fungus infection among COVID-19 patients in India

After first phase of Covid-19, the second wave affects a lot to the Indians with mysterious fungal infection known as Mucormycosis. Here, we reviewed clinical pathogenesis, signs, symptoms and treatment against black fungus. The conclusion revealed that use of immunosuppressant to combat Covid-19 also increases the risk to get infected with mucormycosis. Patients with hyperglycemia, ketoacidosis, solid organ or bone marrow transplantion, liver cirrhosis, neutropenia are more susceptible to get attacked by Mucormycosis moulds. Early diagnosis, removal of predisposing factors, timely antifungal therapy with surgical removal of all infected tissues and adjunctive therapies are four major factors to eradicate Mucormycosis.

Serum iron indices in COVID-19-associated mucormycosis: A case-control study

BACKGROUND

Whether dysregulated iron metabolism is associated with COVID-19-associated mucormycosis (CAM) remains unknown. Herein, we compare the serum iron indices in COVID-19 subjects with and without mucormycosis.

METHODS

We conducted a case-control study enrolling COVID-19 participants with and without mucormycosis. We compared the baseline serum iron indices (iron, ferritin, total iron-binding capacity [TIBC], unsaturated iron-binding capacity and percentage transferrin saturation) between CAM cases and COVID-19 controls. Additionally, we performed a multivariate logistic regression analysis to assess whether any iron indices are associated with CAM.

RESULTS

We enrolled 28 CAM cases (mean age 53.6 years old; 78.6% men) and 26 controls (mean age 57.2 years old; 73.1% men). Rhino-orbital (±cerebral) mucormycosis (85.7%) was the most clinical presentation. Diabetes mellitus was more frequent in the cases than controls (75% vs. 42.3%; p = .015). Hypoxaemia during COVID-19 illness was more common in controls than cases. The mean serum iron values (33 vs. 45 μg/dl, p = .03) and TIBC (166.6 vs. 201.6 μg/dl, p = .003) were significantly lower in CAM cases than controls. On multivariate analysis, we found a lower TIBC (odds ratio [OR] 0.97; 95% confidence interval [CI], 0.95-0.99) and diabetes mellitus (OR 5.23; 95% CI, 1.21-22.68) to be independently associated with CAM after adjusting for serum iron, ferritin and glucocorticoid therapy. The case fatality rate of CAM was 73.9%. The iron indices were not significantly different between CAM survivors and non-survivors.

CONCLUSIONS

The CAM is associated with lower TIBC levels than COVID-19 subjects without mucormycosis, suggesting dysregulated iron metabolism in its pathogenesis. Further studies are required to confirm our preliminary observations.

How Does Mucorales Benefit from the Dysregulated Iron Homeostasis During SARS-CoV-2 Infection?

Mucorales is the cause of mucormycosis, an emerging opportunistic infection in the era of coronavirus disease 2019 (COVID-19) pandemic. Condition of hyperglycemia, diabetes mellitus, and acidosis; dysregulated iron homeostasis in the form of hyperferritinemic syndrome, and high concentration of iron in circulation; and endothelial injury related to abundance glucose regulated protein 78 (GRP78), which are present in severe COVID-19, could favor Mucorales infection. In this short communication, we summarized how the dysregulated iron homeostasis in severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection benefits Mucorales.

Mucormycosis in Indian COVID-19 Patients: Insight into Its Patho-Genesis, Clinical Manifestation, and Management Strategies

Mucormycosis in patients who have COVID-19 or who are otherwise immunocompromised has become a global problem, causing significant morbidity and mortality. Infection is debilitating and fatal, leading to loss of organs and emotional trauma. Radiographic manifestations are not specific, but diagnosis can be made through microscopic examination of materials collected from necrotic lesions. Treatment requires multidisciplinary expertise, as the fungus enters through the eyes and nose and may even reach the brain. Use of the many antifungal drugs available is limited by considerations of resistance and toxicity, but nanoparticles can overcome such limitations by reducing toxicity and increasing bioavailability. The lipid formulation of amphotericin-B (liposomal Am-B) is the first-line treatment for mucormycosis in COVID-19 patients, but its high cost and low availability have prompted a shift toward surgery, so that surgical debridement to remove all necrotic lesions remains the hallmark of effective treatment of mucormycosis in COVID-19. This review highlights the pathogenesis, clinical manifestation, and management of mucormycosis in patients who have COVID-19.

Current Understanding in the Pathophysiology of SARS-CoV-2-Associated Rhino-Orbito-Cerebral Mucormycosis: A Comprehensive Review

AIM

Recently, with the second wave of COVID-19, the Indian subcontinent has witnessed a dramatic rise in mucormycosis infection in patients recovered from COVID-19. This association has been documented in various case reports/case series and institutional experiences, and the mortality associated with this fungal infection is emerging as a cause of concern. The aim of the present paper is to provide a scientific overview on the pathogenesis of mucormycosis in COVID-19 beyond the conventional understanding of the disease process, which may not otherwise explain the increased incidence of mucormycosis in SARS-CoV-2.

METHODOLOGY

This paper is structured as a narrative review of the published literature on the pathogenesis of COVID-19 which contributes to the development of mucormycosis. Apart from the acknowledged role of ketoacidosis, high blood sugar, and iron metabolism in the pathogenesis of mucormycosis, other factors involved in pathophysiology of COVID-19 which might alter or enhance the mucormycosis infection such as (1) the role of ferritin, (2) high serum iron, (3) free radical-induced endothelitis, (4) hepcidin activation, (5) upregulation of glucose receptor protein (GRP78) are discussed in the pathophysiology of COVID-19-associated mucormycosis.

CONCLUSION

A new proposal for the pathogenesis based on the ferritin, viral mimicry of hepcidin and GRP78-CotH3 interaction, which clearly explains the surge in mucormycosis in SARS-CoV-2 infection, has been explained.

COVID-19 associated mucormycosis: Staging and management recommendations (Report of a multi-disciplinary expert committee)

Even before the onslaught of COVID-19 pandemic could settle, the unprecedented rise in cases with COVID-19 associated mucormycosis pushed the medical health to the fringe. Hyperglycaemia and corticosteroids appear to be the most consistent associations leading to the commonest manifestation of mucormycosis, Rhino-Orbito-Cerebral Mucormycosis. To address challenges right from categorisation and staging of the disease to the management of relentless progression, a multi-disciplinary expert committee was formed to handle the task in an evidence-based format to enforce best practices. The report of the committee on one hand attempts to succinctly present the currently available evidence while at the other also attempts to bridge the evidence-deficient gaps with the specialty-specific virtuosity of experts.

Mucormycosis causing massive lower gastrointestinal bleeding: a case report

BACKGROUND

Lower gastrointestinal bleeding (LGIB) is very common in the hospital setting. Most bleedings stop spontaneously, but rare infectious causes of LGIB may lead to rapid and serious complications if left untreated and are sometimes very difficult to diagnose preoperatively.

CASE PRESENTATION

We described a young man with poorly controlled Type I diabetes mellitus and chronic alcohol abuse who presented with acute altered mental status. During his hospitalization for treatment of diabetic ketoacidosis, acute renal failure, and sepsis, he suddenly developed massive hematochezia of 1500 mL. Colonoscopy was performed and a deep ulcer covered with mucus with peripheral elevation was noted at the transverse colon. Biopsy of the ulcer later revealed nonpigmented, wide (5-20 µm in diameter), thin-walled, ribbon-like hyphae with few septations and right-angle branching suggestive of mucormycosis demonstrated by Periodic acid-Schiff stain. He received 2 months of antifungal treatment. Follow up colonoscopy post-treatment was normal with no ulcer visualized.

CONCLUSIONS

Early diagnosis and treatment of gastrointestinal (GI) mucormycosis infection is critical but can be challenging, especially in the setting of massive hematochezia. Therefore, clinical awareness for immunocompromised patients and prompt antifungal prophylaxis in cases with high suspicion of infection are essential.

Cutaneous and subcutaneous fungal infections: recent developments on host-fungus interactions

The incidence of skin fungal infections is increasing at an alarming rate worldwide, presenting a major challenge to health professionals. Cutaneous and subcutaneous fungal infections are caused by pathogenic or opportunistic organisms varying from mold, yeasts, to dimorphic fungi. Recently, skin fungal have been increasingly reported and studied, giving rise to crucial breakthroughs in etiology and pathogenesis. This review aims to summarize recent insights into the clinical and etiological characteristics of common skin fungal infections according to different fungal species, as well as remarkable advances in the immune mechanisms. We hope it will be helpful to understand these diverse skin fungal infections, and bring about the latest developments that may facilitate novel diagnostic and therapeutic approaches to improve the outcomes in these patients.

Evaluation of Sex Differences in Murine Diabetic Ketoacidosis and Neutropenic Models of Invasive Mucormycosis

There is increased concern that the quality, generalizability and reproducibility of biomedical research can be influenced by the sex of animals used. We studied the differences between male and female mice in response to invasive pulmonary mucormycosis including susceptibility to infection, host immune reaction and responses to antifungal therapy. We used diabetic ketoacidotic (DKA) or neutropenic mice infected with either Rhizopus delemar or Mucor circinelloides. The only difference detected was that when DKA mice were infected with M. circinelloides, female mice were more resistant to infection than male mice (median survival time of 5 vs. 2 days for female and male mice, respectively). However, a 100% lethality was detected among infected animals of both sexes. Treatment with either liposomal amphotericin B (L-AMB) or posaconazole (POSA) protected mice from infection and eliminated the difference seen between infected but untreated female and male mice. Treatment with L-AMB consistently outperformed POSA in prolonging survival and reducing tissue fungal burden of DKA and neutropenic mice infected with R. delemar or M. circinelloides, in both mouse sexes. While little difference was detected in cytokine levels among both sexes, mucormycosis infection in the DKA mouse model induced more inflammatory cytokines/chemokines involved in neutrophil (CXCL1) and macrophage (CXCL2) recruitment vs. uninfected mice. As expected, this inflammatory response was reduced in the neutropenic mouse model. Our studies show that there are few differences between female and male DKA or neutropenic mice infected with mucormycosis with no effect on the outcome of treatment or host immune response.

Mucoricin is a ricin-like toxin that is critical for the pathogenesis of mucormycosis

Fungi of the order Mucorales cause mucormycosis, a lethal infection with an incompletely understood pathogenesis. We demonstrate that Mucorales fungi produce a toxin, which plays a central role in virulence. Polyclonal antibodies against this toxin inhibit its ability to damage human cells in vitro and prevent hypovolemic shock, organ necrosis and death in mice with mucormycosis. Inhibition of the toxin in Rhizopus delemar through RNA interference compromises the ability of the fungus to damage host cells and attenuates virulence in mice. This 17 kDa toxin has structural and functional features of the plant toxin ricin, including the ability to inhibit protein synthesis through its N-glycosylase activity, the existence of a motif that mediates vascular leak and a lectin sequence. Antibodies against the toxin inhibit R. delemar- or toxin-mediated vascular permeability in vitro and cross react with ricin. A monoclonal anti-ricin B chain antibody binds to the toxin and also inhibits its ability to cause vascular permeability. Therefore, we propose the name 'mucoricin' for this toxin. Not only is mucoricin important in the pathogenesis of mucormycosis but our data suggest that a ricin-like toxin is produced by organisms beyond the plant and bacterial kingdoms. Importantly, mucoricin should be a promising therapeutic target.

A closer look at pathogenesis of cerebral mucormycosis in diabetic condition: A mini review

Patients with diabetes are considered a high-risk group involved with cerebral mucormycosis (CM). Due to the potential of Mucorales to invade sinuses and its rapid progression into orbit and retro-orbital areas and even brain, in most cases, CM is fatal in patients with diabetes. In the last few decades, mucormycosis and background conditions responsible for the development of its infections have received a great deal of attention. Dysfunction of innate and adaptive immune system, the increased amount of available nutrition, expression of host factors, and free iron level in plasma in diabetic ketoacidosis are among the topics that have been mostly taken into account so far. Therefore, it is important to clarify the molecular mechanisms that let the Mucorales to involve the patients with diabetes, which even at early stages of diagnosis and treatment, there is minimum chance to control the disease.

Fungal iron homeostasis with a focus on Aspergillus fumigatus

To maintain iron homeostasis, fungi have to balance iron acquisition, storage, and utilization to ensure sufficient supply and to avoid toxic excess of this essential trace element. As pathogens usually encounter iron limitation in the host niche, this metal plays a particular role during virulence. Siderophores are iron-chelators synthesized by most, but not all fungal species to sequester iron extra- and intracellularly. In recent years, the facultative human pathogen Aspergillus fumigatus has become a model for fungal iron homeostasis of siderophore-producing fungal species. This article summarizes the knowledge on fungal iron homeostasis and its links to virulence with a focus on A. fumigatus. It covers mechanisms for iron acquisition, storage, and detoxification, as well as the modes of transcriptional iron regulation and iron sensing in A. fumigatus in comparison to other fungal species. Moreover, potential translational applications of the peculiarities of fungal iron metabolism for treatment and diagnosis of fungal infections is addressed.

Rhinocerebral mucormycosis caused by Rhizopus oryzae in a patient with acute myeloid leukemia: A case report

BACKGROUND

Rhinocerebral mucormycosis (RCM) is a rare fatal fungal infection which is on the increase among immunocompromised hosts such as patients who have had hematological cancers, or have received immunosuppressive drugs, corticosteroids, or other T cell suppressing agents.

CASE SUMMARY

We report a case of RCM caused by Rhizopus oryzae, one of the most common opportunistic pathogens, in a patient suffering from a fourth relapse of acute myeloid leukemia. The patient developed RCM after he had received long-term antibiotic agents and corticosteroids. The pathogen was isolated three times from nasal secretions collected from the deep parts of the nasal cavity and was identified by morphology and internal transcribed spacer sequencing. Blood infection was excluded by droplet digital polymerase chain reaction and blood culture. The patient was empirically treated with caspofungin and voriconazole for several days while the lesions continued to progress. The patient was given amphotericin B in combination with caspofungin after RCM was suspected, and the lesions improved over the course of treatment, which lasted several days. However, the patient eventually died of the primary disease.

CONCLUSION

This case indicates that immunosuppressive drugs, including corticosteroids and antimetabolites in hematological tumor, do increase the risk of infections of this type. Early diagnosis, prompt and frequent surgical debridement, and treatment with amphotericin B without delay are all essential in combatting RCM.

Preserving Vascular Integrity Protects Mice against Multidrug-Resistant Gram-Negative Bacterial Infection

The rise in multidrug-resistant (MDR) organisms portends a serious global threat to the health care system with nearly untreatable infectious diseases, including pneumonia and its often fatal sequelae, acute respiratory distress syndrome (ARDS) and sepsis. Gram-negative bacteria (GNB), including Acinetobacter baumannii, Pseudomonas aeruginosa, and carbapenemase-producing Klebsiella pneumoniae (CPKP), are among the World Health Organization's and National Institutes of Health's high-priority MDR pathogens for targeted development of new therapies. Here, we show that stabilizing the host's vasculature by genetic deletion or pharmacological inhibition of the small GTPase ADP-ribosylation factor 6 (ARF6) increases survival rates of mice infected with A. baumannii, P. aeruginosa, and CPKP. We show that the pharmacological inhibition of ARF6-GTP phenocopies endothelium-specific Arf6 disruption in enhancing the survival of mice with A. baumannii pneumonia, suggesting that inhibition is on target. Finally, we show that the mechanism of protection elicited by these small-molecule inhibitors acts by the restoration of vascular integrity disrupted by GNB lipopolysaccharide (LPS) activation of the TLR4/MyD88/ARNO/ARF6 pathway. By targeting the host's vasculature with small-molecule inhibitors of ARF6 activation, we circumvent microbial drug resistance and provide a potential alternative/adjunctive treatment for emerging and reemerging pathogens.

GRP78 and Integrins Play Different Roles in Host Cell Invasion during Mucormycosis

Mucormycosis, caused by Rhizopus species, is a life-threatening fungal infection that occurs in patients immunocompromised by diabetic ketoacidosis (DKA), cytotoxic chemotherapy, immunosuppressive therapy, hematologic malignancies, or severe trauma. Inhaled Rhizopus spores cause pulmonary infections in patients with hematologic malignancies, while patients with DKA are much more prone to rhinoorbital/cerebral mucormycosis. Here, we show that Rhizopus delemar interacts with glucose-regulated protein 78 (GRP78) on nasal epithelial cells via its spore coat protein CotH3 to invade and damage the nasal epithelial cells. Expression of the two proteins is significantly enhanced by high glucose, iron, and ketone body levels (hallmark features of DKA), potentially leading to frequently lethal rhinoorbital/cerebral mucormycosis. In contrast, R. delemar CotH7 recognizes integrin β1 as a receptor on alveolar epithelial cells, causing the activation of epidermal growth factor receptor (EGFR) and leading to host cell invasion. Anti-integrin β1 antibodies inhibit R. delemar invasion of alveolar epithelial cells and protect mice from pulmonary mucormycosis. Our results show that R. delemar interacts with different mammalian receptors depending on the host cell type. Susceptibility of patients with DKA primarily to rhinoorbital/cerebral disease can be explained by host factors typically present in DKA and known to upregulate CotH3 and nasal GRP78, thereby trapping the fungal cells within the rhinoorbital milieu, leading to subsequent invasion and damage. Our studies highlight that mucormycosis pathogenesis can potentially be overcome by the development of novel customized therapies targeting niche-specific host receptors or their respective fungal ligands.IMPORTANCE Mucormycosis caused by Rhizopus species is a fungal infection with often fatal prognosis. Inhalation of spores is the major route of entry, with nasal and alveolar epithelial cells among the first cells that encounter the fungi. In patients with hematologic malignancies or those undergoing cytotoxic chemotherapy, Rhizopus causes pulmonary infections. On the other hand, DKA patients predominantly suffer from rhinoorbital/cerebral mucormycosis. The reason for such disparity in disease types by the same fungus is not known. Here, we show that the unique susceptibility of DKA subjects to rhinoorbital/cerebral mucormycosis is likely due to specific interaction between nasal epithelial cell GRP78 and fungal CotH3, the expression of which increases in the presence of host factors present in DKA. In contrast, pulmonary mucormycosis is initiated via interaction of inhaled spores expressing CotH7 with integrin β1 receptor, which activates EGFR to induce fungal invasion of host cells. These results introduce a plausible explanation for disparate disease manifestations in DKA versus those in hematologic malignancy patients and provide a foundation for development of therapeutic interventions against these lethal forms of mucormycosis.

Genes, Pathways, and Mechanisms Involved in the Virulence of Mucorales

The order Mucorales is a group of ancient fungi with limited tools for gene manipulation. The main consequence of this manipulation unwillingness is the limited knowledge about its biology compared to other fungal groups. However, the emerging of mucormycosis, a fungal infection caused by Mucorales, is attracting the medical spotlight in recent years because the treatments available are not efficient in reducing the high mortality associated with this disease. The result of this renewed interest in Mucorales and mucormycosis is an extraordinarily productive effort to unveil their secrets during the last decade. In this review, we describe the most compelling advances related to the genetic study of virulence factors, pathways, and molecular mechanisms developed in these years. The use of a few genetic study models has allowed the characterization of virulence factors in Mucorales that were previously described in other pathogens, such as the uptake iron systems, the mechanisms of dimorphism, and azole resistances. More importantly, recent studies are identifying new genes and mechanisms controlling the pathogenic potential of Mucorales and their interactions with the host, offering new alternatives to develop specific strategies against mucormycosis.