CARD9 Deficiency in a Chinese Man with Cutaneous Mucormycosis, Recurrent Deep Dermatophytosis and a Review of the Literature

Phialophora americana infection in a patient with a compound heterozygous CARD9 mutation

Phaeohyphomycosis caused by Phialophora americana is relatively rare in clinical practice. Deficiency in the human caspase recruitment domain-containing protein 9 (CARD9) is associated with infections caused by Phialophora americana. In this case, the patient has had a decade-long history of recurrent tinea corporis and recently presented with an invasive, deep subcutaneous infection in the right axilla caused by Phialophora americana. Metagenomic next-generation sequencing (mNGS) confirmed that the pathogen infecting the patient was Phialophora americana. Whole exome sequencing (WES) revealed that the patient had compound heterozygous CARD9 gene mutations, with a c.952-1G > A mutation in intron 6 and a c.184 + 5G > T mutation in intron 2. The expression of the CARD9 protein and the levels of cytokines, including IL-17 and IFN-γ, were observed to be decreased in the patient. After an ineffective treatment with amphotericin B, voriconazole was administered for antifungal therapy and yielded satisfactory results. Following discharge, the patient continued oral voriconazole for ongoing antifungal treatment. One month after discharge, the patient returned to the hospital for a follow-up examination, during which it was observed that the symptoms had been successfully resolved. The novel compound heterozygous mutations may lead to CARD9 deficiency, which in turn results in susceptibility to Phialophora americana infection.

Evaluation of Inborn Errors of Immunity Among Patients with Opportunistic Pulmonary Infection

This review of immunocompromised host pneumonia as the result of inborn errors of immunity (IEI) is organized by opportunistic pulmonary pathogen. The authors identify patients who warrant an evaluation for an IEI based on their clinical presentation. Their recommendations are guided by the immune defect(s) associated with each opportunistic pulmonary infection. Physicians without expertise in immunology may begin an evaluation for IEI using the guidance provided here. Comprehensive evaluation by an immunologist may also be warranted in many instances.

A case of disseminated autochthonous Cladophialophora bantiana infection in a renal transplant recipient in the UK

Disease associated with Cladophialophora bantiana infection is uncommon but can be characterised by severe and life-threatening CNS involvement. Diagnosis is challenging due to both the infection's rarity and non-specific clinical presentation, which can mimic malignancy and infection caused by more common organisms. Transmission can occur via inhalation or inoculation through compromised skin, followed by haematogenous dissemination to the brain and other organs. We report a case of a 42-year-old renal transplant recipient with no travel history presenting with neurological symptoms and skin and lung lesions due to C bantiana infection. An aggressive treatment approach comprising combination antifungal therapy, surgical debridement, and withdrawal of immunosuppression resulted in disease control, although this treatment was complicated by voriconazole-induced skeletal fluorosis. This organism, more commonly encountered in tropical regions, has traditionally been considered imported into the UK by returning travellers, therefore this case of autochthonous infection could reflect an expanding range alongside global climactic shifts.

The CARD9 Gene in Koalas (Phascolarctos cinereus): Does It Play a Role in the Cryptococcus-Koala Interaction?

Cryptococcus is a genus of fungal pathogens that can infect and cause disease in a range of host species and is particularly prominent in koalas (Phascolarctos cinerus). Like other host species, koalas display a range of outcomes upon exposure to environmental Cryptococcus, from external nasal colonization to asymptomatic invasive infection and, in rare cases, severe clinical disease resulting in death. Host factors contributing to these varied outcomes are poorly understood. Due to their close relationship with eucalypt trees (a key environmental niche for Cryptococcus gattii) and suspected continual exposure to the pathogen, koalas provide a unique opportunity to examine host susceptibility in natural infections. Caspase recruitment domain-containing protein 9 (CARD9) is a key intracellular signaling protein in the fungal innate immune response. Humans with mutations in CARD9 succumb to several different severe and chronic fungal infections. This study is the first to sequence and explore CARD9 variation in multiple koalas using Sanger sequencing. Four CARD9 exons were successfully sequenced in 22 koalas from a New South Wales, Australia population. We found minimal variation between koalas across all four exons, an observation that was also made when CARD9 sequences were compared between koalas and six other species, including humans and mice. Ten single-nucleotide polymorphisms (SNP) were identified in this study and explored in the context of cryptococcal exposure outcomes. While we did not find any significant association with variation in cryptococcal outcomes, we found a high degree of conservation between species at several SNP loci that requires further investigation. The findings from this study lay the groundwork for further investigations of CARD9 and Cryptococcus both in koalas and other species, and highlight several considerations for future studies.

Inherited CARD9 Deficiency Due to a Founder Effect in East Asia

Autosomal recessive CARD9 deficiency can underly deep and superficial fungal diseases. We identified two Japanese patients, suffering from superficial and invasive Candida albicans diseases, carrying biallelic variants of CARD9. Both patients, in addition to another Japanese and two Korean patients who were previously reported, carried the c.820dup CARD9 variant, either in the homozygous (two patients) or heterozygous (three patients) state. The other CARD9 alleles were c.104G > A, c.1534C > T and c.1558del. The c.820dup CARD9 variant has thus been reported, in the homozygous or heterozygous state, in patients originating from China, Japan, or South Korea. The Japanese, Korean, and Chinese patients share a 10 Kb haplotype encompassing the c.820dup CARD9 variant. This variant thus originates from a common ancestor, estimated to have lived less than 4,000 years ago. While phaeohyphomycosis caused by Phialophora spp. was common in the Chinese patients, none of the five patients in our study displayed Phialophora spp.-induced disease. This difference between Chinese and our patients probably results from environmental factors. (161/250).

From Mendel to mycoses: Immuno-genomic warfare at the human-fungus interface

Fungi are opportunists: They particularly require a defect of immunity to cause severe or disseminated disease. While often secondary to an apparent iatrogenic cause, fungal diseases do occur in the absence of one, albeit infrequently. These rare cases may be due to an underlying genetic immunodeficiency that can present variably in age of onset, severity, or other infections, and in the absence of a family history of disease. They may also be due to anti-cytokine autoantibodies. This review provides a background on how human genetics or autoantibodies underlie cases of susceptibility to severe or disseminated fungal disease. Subsequently, the lessons learned from these inborn errors of immunity marked by fungal disease (IEI-FD) provide a framework to begin to mechanistically decipher fungal syndromes, potentially paving the way for precision therapy of the mycoses.

Deep dermatophytosis caused by Trichophyton rubrum in an elderly patient with CARD9 deficiency: A case report and literature review

Deep dermatophytosis is an invasive and sometimes life-threatening fungal infection mainly reported in immunocompromised patients. However, a caspase recruitment domain-containing protein 9 (CARD9) deficiency has recently been reported to cause deep dermatophytosis. Herein, we report the first Japanese case of deep dermatophytosis associated with CARD9 deficiency. An 80-year-old Japanese man with tinea corporis presented with subcutaneous nodules on his left sole. Histopathological findings revealed marked epithelioid cell granulomas with filamentous fungal structures in the deep dermis and subcutis, and the patient was diagnosed with deep dermatophytosis. Despite antifungal therapy, the subcutaneous nodule on his left sole gradually enlarged, his left calcaneal bone was invaded, and the patient finally underwent amputation of his left leg. Genetic analysis revealed a homozygous CARD9 c.586 A > G (p. Lys196Glu) variant, suggesting a CARD9 deficiency. Here, we discuss the clinical features of CARD9 deficiency-associated deep dermatophytosis with a case report and review of the literature.

Erythroderma combined with deeper dermal dermatophytosis due to Trichophyton rubrum in a patient with myasthenia gravis: first case report and literature review

BACKGROUND

Dermatophytes are the most common causative pathogens of mycoses worldwide and usually cause superficial infections. However, they can enter deep into the dermis lead to invasive dermatophytosis such as deeper dermal dermatophytosis on rare occasions. Erythroderma is a severe dermatological manifestation of various diseases resulting in generalized skin redness, but erythroderma due to fungi infections is barely reported. In this article, we reported the first case of erythroderma combined with deeper dermal dermatophytosis due to Trichophyton rubrum (T. rubrum) in a patient with myasthenia gravis.

CASE PRESENTATION

A 48-year-old man was hospitalized because of erythema with scaling and nodules covering his body for a month. The patient had a history of myasthenia gravis controlled by regularly taking prednisolone for > 10 years and accompanied by onychomycosis and tinea pedis lasting > 8 years. Based on histopathological examinations, fungal cultures, and DNA sequencing results, the patient was finally diagnosed with dermatophyte-induced erythroderma combined with deeper dermal dermatophytosis caused by T. rubrum. After 2 weeks of antifungal treatment, the patient had recovered well.

CONCLUSIONS

This case report shows that immunosuppressed patients with long histories of superficial mycoses tend to have a higher risk of developing invasive dermatophytic infections or disseminated fungal infections. Dermatologists should be alert to this condition and promptly treat the superficial dermatophytosis.

Mucormycosis and Its Upsurge During COVID-19 Epidemic: An Updated Review

Although mucormycosis may have reached an epidemic situation during the COVID-19 pandemic, the term was much more familiar even before the COVID-19 period. The year 2020 showed an outbreak of novel coronavirus (SARS-CoV-2) which affected millions of people all over the world. One of the noticeable complications observed to be associated with this disease is mucormycosis. It is an opportunistic infection caused by members of the Order Mucorales existing worldwide and has been commonly reported as a laboratory contaminant for a long time. However, nowadays due to the changes in the host environment, they have been emerging as potent opportunistic pathogens responsible for causing primary infections or coinfections with other diseases eventually resulting in morbidity and even mortality in severe cases. Although immunocompromised patients are more susceptible to this infection, few cases have been reported in immunocompetent individuals. Various risk factors which are responsible for the acquisition of mucormycosis include diabetes mellitus type 2, ketoacidosis, hematological malignancies, organ transplants, and chemotherapy recipients. Among the various etiological agents, Rhizopus is found to be the most common, and rhino-cerebral to be the most frequent clinical presentation. As far as pathogenesis is concerned, host cell invasion, thrombosis, and necrosis are the main events in the progression of this disease. The aim of the present review is to address a complete spectrum of mucormycosis and COVID-19-associated mucormycosis (CAM) in a single article. Both global and Indian scenarios of mucormycosis are taken into account while framing this review.

Of Mycelium and Men: Inherent Human Susceptibility to Fungal Diseases

In medical mycology, the main context of disease is iatrogenic-based disease. However, historically, and occasionally, even today, fungal diseases affect humans with no obvious risk factors, sometimes in a spectacular fashion. The field of “inborn errors of immunity” (IEI) has deduced at least some of these previously enigmatic cases; accordingly, the discovery of single-gene disorders with penetrant clinical effects and their immunologic dissection have provided a framework with which to understand some of the key pathways mediating human susceptibility to mycoses. By extension, they have also enabled the identification of naturally occurring auto-antibodies to cytokines that phenocopy such susceptibility. This review provides a comprehensive update of IEI and autoantibodies that inherently predispose humans to various fungal diseases.

Inborn Errors of Immunity Causing Pediatric Susceptibility to Fungal Diseases

Inborn errors of immunity are a heterogeneous group of genetically determined disorders that compromise the immune system, predisposing patients to infections, autoinflammatory/autoimmunity syndromes, atopy/allergies, lymphoproliferative disorders, and/or malignancies. An emerging manifestation is susceptibility to fungal disease, caused by yeasts or moulds, in a superficial or invasive fashion. In this review, we describe recent advances in the field of inborn errors of immunity associated with increased susceptibility to fungal disease.

Case report: Severe deep ulcer on the left abdomen mimicking mycosis fungoides caused by Trichophyton tonsurans in a patient with novel CARD9 mutation

Dermatophytosis is the most common type of superficial fungal infection caused by dermatophytes. Occasionally, the fungus invades deep into the dermis or other tissues, causing deep dermatophytosis. Deep dermatophytosis is often associated with Caspase Recruitment Domain-containing protein 9 (CARD9) deficiency in patients. Here, we report the first case of deep dermatophytosis with a rare mycosis fungoides manifestation caused by T. tonsurans in a patient with a novel mutation in exon 4 of CARD9. The condition presented with heterozygous K196E mutation, which leads to deficiency of innate and adaptive immune responses in the patient, and caused intractable severe lesions. The patient received treatment with multiple antifungal drugs and was ultimately alleviated by posaconazole. These findings extend the pathogen spectrum of deep dermatophytosis linked with CARD9 deficiency and enriched their phenotypic spectrum.

CARD9 Signaling, Inflammation, and Diseases

Caspase-recruitment domain 9 (CARD9) protein is expressed in many cells especially in immune cells, and is critically involved in the function of the innate and adaptive immune systems through extensive interactions between CARD9 and other signaling molecules including NF-κB and MAPK. CARD9-mediated signaling plays a central role in regulating inflammatory responses and oxidative stress through the productions of important cytokines and chemokines. Abnormalities of CARD9 and CARD9 signaling or CARD9 mutations or polymorphism are associated with a variety of pathological conditions including infections, inflammation, and autoimmune disorders. This review focuses on the function of CARD9 and CARD9-mediated signaling pathways, as well as interactions with other important signaling molecules in different cell types and the relations to specific disease conditions including inflammatory diseases, infections, tumorigenesis, and cardiovascular pathologies.

Mucormycosis in Mainland China: A Systematic Review of Case Reports

Background

Mucormycosis is a lethal fungal infection with increasing incidence. The epidemiology of mucormycosis in current mainland China has not been fully elucidated.

Objectives

To investigate the epidemiology, risk factors, manifestations, diagnosis, treatment and prognosis of mucormycosis in mainland China.

Methods

We searched for published mucormycosis case reports/series in mainland China in the PubMed, WanFang and China National Knowledge Infrastructure databases from January 2001 to July 2020. Cases of proven/probable mucormycosis were included.

Results

A total of 390 cases were included in this review. Most of the patients were male (61.3%), and diabetes was the most common predisposing factor (37.2%). Pulmonary mucormycosis (42.1%) was the most common form followed by cutaneous infection (21.0%). Of 390 patients, 24 died before therapy. Among the remaining 366 patients, 208 (56.8%) received antifungal drugs alone, 16 (4.4%) received surgery alone, and 142 (38.8%) received a combination of drugs and surgery, the mortality of the last group is much lower (34/142, 23.9%). The overall mortality was 37.2%. A multivariate analysis indicated that factors associated with increased mortality included corticosteroid use alone as immunosuppressive therapy, rhino-orbito-cerebral or disseminated mucormycosis (compared with pulmonary mucormycosis), and drug administration other than amphotericin B (AmB), posaconazole (POS) and itraconazole (ITR) (compared with the use of conventional AmB), while factors associated with decreased mortality included cutaneous mucormycosis and surgical therapy. Combination or sequential antifungal therapy of AmB and POS or ITR did not reduce mortality compared with conventional AmB monotherapy.

Conclusion

In mainland China, mucormycosis is a serious fungal infection with high mortality. Corticosteroid use, rhino-orbito-cerebral and disseminated mucormycosis were adverse prognostic factors. Antifungal therapy combined with surgery could improve the prognosis.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11046-021-00607-4.

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.

Trends in the epidemiology of dermatophytosis in the Middle East and North Africa region

Dermatophytosis corresponds to a broad series of infections, mostly superficial, caused by a group of keratinophilic and keratinolytic filamentous fungi called dermatophytes. These mycoses are currently considered to be a major public health concern worldwide, particularly in developing countries such as those in the Middle East and North Africa (MENA) region. Here we compiled and discussed existing epidemiologic data on these infections in the MENA region. Most of the available studies were based on conventional diagnostic strategies and were published before the last taxonomic revision of dermatophytes. This has led to misidentifications, which might have resulted in the underestimation of the real burden of these infections in the MENA countries. Our analysis of the available literature highlights an urgent need for further studies based on reliable diagnostic tools and standard susceptibility testing methods for dermatophytosis, which represents a major challenge for these countries. This is crucial for guiding appropriate interventions and activating antifungal stewardship programs in the future.

In Vivo and In Vitro Impairments in T Helper Cell and Neutrophil Responses against Mucor irregularis in Card9 Knockout Mice

Mucor irregularis is a frequently found fungus in Asia, especially China, and it causes primary cutaneous mucormycosis with a high rate of disfigurement. Caspase recruitment domain-containing protein 9 (Card9) is an essential adaptor molecule downstream of C-type lectin receptors. It mediates the activation of nuclear factor kappa B (NF-κB), regulates T helper 1 (Th1) and Th17 differentiation, and plays an important role in fungal immune surveillance. CARD9 deficiency correlates with the increased susceptibility to many fungal infections, including cutaneous mucormycosis caused by M. irregularis However, the underlying immunological mechanisms were not elucidated. Our study established a murine model of subcutaneous M. irregularis infection, and we isolated immune cells, including bone marrow-derived macrophages, bone marrow-derived dendritic cells, naive T cells, and neutrophils, from wild-type (WT) and Card9 knockout (Card9^-/- ) mice to examine the antifungal effect of Card9 on M. irregularis in vivo and in vitro Card9^-/- mice exhibited increased susceptibility to M. irregularis infection. Impaired local cytokine and chemokine production, NF-κB (p65) activation, and Th1/17 cell differentiation and partially impaired neutrophil-dependent antifungal immunity were observed in Card9^-/- mice. This work enriches our knowledge of the relationship between CARD9 deficiency and mucormycosis.