Cutaneous manifestations of endemic mycoses

Genome-level therapeutic targets identification and chimeric Vaccine designing against the Blastomyces dermatitidis

Blastomyces dermatitidis is a thermally dimorphic fungus that can cause serious and sometimes fatal infections, including blastomycosis. After spore inhalation, a pulmonary infection develops, which can be asymptomatic and have lethal effects, such as acute respiratory distress syndrome. Its most common extra-pulmonary sites are the central nervous system, bones, skin, and genito-urinary systems. Currently, no vaccine has been approved by the FDA to prevent this infection. In the study, a peptide-based vaccine was developed against blastomycosis by using subtractive proteomics and reverse vaccinology approaches. It focuses on mining the whole genome of B. dermatitidis, identifying potential therapeutic targets, and pinpointing potential epitopes for both B- and T-cells that are immunogenic, non-allergenic, non-toxic, and highly antigenic. Multi-epitope constructs were generated by incorporating appropriate linker sequences. A linker (EAAAK) was also added to incorporate an adjuvant sequence to increase immunological potential. The addition of adjuvants and linkers ultimately resulted in the formation of a vaccine construct in which the number of amino acids was 243 and the molecular weight was 26.18 kDa. The designed antigenic and non-allergenic vaccine constructs showed suitable physicochemical properties. The vaccine's structures were predicted, and further analysis verified their interactions with the human TLR-4 receptor through protein-protein docking. Additionally, MD simulation showed a potent interaction between prioritized vaccine-receptor complexes. Immune simulation predicted that the final vaccine injections resulted in significant immune responses for the T- and B-cell immune responses. Moreover, in silico cloning ensured a high expression possibility of the lead vaccine in the E. coli (K12) vector. This study offers an initiative for the development of effective vaccines against B. dermatitidis; however, it is necessary to validate the designed vaccine's immunogenicity experimentally.

Disseminated Blastomycosis in an Immunocompetent Patient

Blastomycoses dermatitidis is a dimorphic fungus that can cause disseminated blastomycosis with varying clinical manifestations and multiorgan involvement. While blastomycosis commonly causes pulmonary disease, extrapulmonary spread can result in skin, bone, and central nervous system involvement. Cutaneous blastomycosis can present as pustular lesions that evolve into ulcerative or verrucous plaques. We present a case of disseminated blastomycosis in an immunocompetent patient with both pulmonary and cutaneous features. The patient developed hypoxic respiratory failure and was subsequently diagnosed with disseminated blastomycosis after undergoing bronchoscopy with bronchial washing. He was found to have ulcerative nasal lesions as part of his disseminated disease. He was successfully treated with amphotericin B and ultimately discharged from the hospital.

The Ecology of Non-Candida Yeasts and Dimorphic Fungi in Cetaceans: From Pathogenicity to Environmental and Global Health Implications

Cetaceans, which are integral to marine ecosystems, face escalating anthropogenic threats, including climate change and pollution, positioning them as critical sentinel species for ocean and human health. This review explores the neglected realm of non-Candida yeasts in cetaceans, addressing the gaps in the understanding of their prevalence, pathogenicity, and environmental impacts. By examining identified species such as Cryptococcus spp., Paracoccidioides spp., and several dimorphic fungi, this review emphasizes global prevalence, epidemiology and ecology, pathogenicity, and potential zoonotic implications. It also discusses the fine line between yeast commensalism and pathogenicity by considering environmental influences such as pollution, climate shifts, and immune suppression. Environmental impact discussions delve into how rising ocean temperatures and pollution can modify yeast mycobiota, potentially affecting marine host health and broader ecosystem dynamics. The cetacean's unique physiology and ecological niches are considered, highlighting potential impacts on behaviors, reproductive success, and survival rates. Identifying crucial knowledge gaps, the review calls for intensified research efforts, employing advanced molecular techniques to unravel the cetacean mycobiome. Systematic studies on yeast diversity, antifungal susceptibility, and their influence on environmental and ecosystem health are proposed, and the balance between commensal and pathogenic species emphasizes the significance of the One Health approach. In conclusion, as marine mammals face unprecedented challenges, unveiling non-Candida yeasts in cetaceans emerges as a critical endeavor with far-reaching implications for the conservation of marine ecosystems and for both animal and human public health.

Blastomycosis: A Review of Mycological and Clinical Aspects

Blastomycosis is caused by a thermally dimorphic fungus that thrives in moist acidic soil. Blastomyces dermatitidis is the species responsible for most infections in North America and is especially common in areas around the Great Lakes, the St. Lawrence Seaway, and in several south-central and southeastern United States. Other Blastomyces species have more recently been discovered to cause disease in distinct geographic regions around the world. Infection almost always occurs following inhalation of conidia produced in the mold phase. Acute pulmonary infection ranges from asymptomatic to typical community-acquired pneumonia; more chronic forms of pulmonary infection can present as mass-like lesions or cavitary pneumonia. Infrequently, pulmonary infection can progress to acute respiratory distress syndrome that is associated with a high mortality rate. After initial pulmonary infection, hematogenous dissemination of the yeast form of Blastomyces is common. Most often this is manifested by cutaneous lesions, but osteoarticular, genitourinary, and central nervous system (CNS) involvement also occurs. The diagnosis of blastomycosis can be made by growth of the mold phase of Blastomyces spp. in culture or by histopathological identification of the distinctive features of the yeast form in tissues. Detection of cell wall antigens of Blastomyces in urine or serum provides a rapid method for a probable diagnosis of blastomycosis, but cross-reactivity with other endemic mycoses commonly occurs. Treatment of severe pulmonary or disseminated blastomycosis and CNS blastomycosis initially is with a lipid formulation of amphotericin B. After improvement, therapy can be changed to an oral azole, almost always itraconazole. With mild to moderate pulmonary or disseminated blastomycosis, oral itraconazole treatment is recommended.

Blastomycosis-Some Progress but Still Much to Learn

Blastomycosis, caused by Blastomyces spp., is an endemic mycosis capable of causing significant disease throughout the body. Higher rates of infection are seen in the Mississippi and Ohio River valleys, the Great Lakes region of the United States and Canada, much of Africa, and, to a lesser extent, in India and the Middle East. Limited reporting inhibits our true understanding of the geographic distribution of blastomycosis. An estimated 50% of those infected remain asymptomatic. Of those who present with symptomatic disease, pulmonary involvement is most common, while the most common extrapulmonary sites are the skin, bones, genitourinary system, and central nervous system. Itraconazole is the standard therapy for mild-moderate disease. Data for other azoles are limited. Amphotericin is used for severe disease, and corticosteroids are occasionally used in severe disease, but evidence for this practice is limited. Despite increasing incidence and geographic reach in recent years, there are still significant knowledge gaps in our understanding of blastomycosis. Here, we provide an updated review of the epidemiology, clinical presentations, and diagnostic and therapeutic approaches for this infection. We also discuss areas needing further research.

Blastomycosis

Blastomycosis is the fungal disease caused by thermally dimorphic fungi in the genus Blastomyces, with B dermatitidis complex causing most cases. It is considered hyperendemic in areas adjacent to the Great Lakes and along the St. Lawrence, Mississippi, and Ohio rivers, but definitive geographic distribution of blastomycoses remains obscure. Clinical presentation is variable. Disseminated blastomycosis with extrapulmonary manifestations is more common in immunosuppressed individuals. Culture positivity is required for definitive diagnosis, but compatible histology is often sufficient for presumptive diagnosis and initiation of treatment. Treatment should be provided to all symptomatic cases to prevent progression or recurrence.

Deep fungal infections diagnosed by histology in Uganda: a 70-year retrospective study

Fungal infections cause substantial morbidity and mortality. However, the burden of deep fungal infections is not well described in Uganda. We aimed to estimate the burden and etiology of histologically diagnosed deep fungal infections in Uganda. We retrospectively reviewed histology reports at the Pathology Reference Laboratory, Department of Pathology, Makerere University, Kampala, Uganda from January 1950 to September 2019 to identify any reports that had a fungal infection as the diagnosis. Over the study period, 697 cases of deep fungal infections were identified with an average incidence of 0.73/100,000 persons per decade. There was a general decline in the number of cases detected. Median age of the cases was 28 years (IQR: 11-40) and majority (59%) were male. The age group of 0-10 years were the most affected. The foot was the most affected part of the body (26%). Deep mycoses identified include eumycetoma (32%), subcutaneous phycomycosis (26%), histoplasmosis (9.2%), chromoblastomycosis (4.6%), aspergillosis (3.3%), cryptococcosis (3.3%), blastomycosis (1.6%), subcutaneous mycosis (1.4%), dermatomycosis (1.3%), coccidioidomycosis (0.6%), mucormycosis (0.6%), and sporotrichosis (0.1%). Histoplasma was the commonest causative agent (9.2%) followed by Aspergillus (3.4%) and Cryptococcus (3.3%), while 81% of the fungal pathogens were not identified to genus/species level. Only 31% of the cases were diagnosed clinically as deep fungal infections. There is a substantial burden of deep fungal infections caused by multiple fungal pathogens in Uganda. There is need to build local capacity for mycology so as to improve on the index of clinical suspicion and diagnostic capabilities.

Unremitting Pain and Fever in a 15-Year-Old Boy With Osteomyelitis

A previously healthy 15-year-old boy from a rural county in the southeastern United States was evaluated in the emergency department with fever and worsening toe pain in the absence of trauma. He initially presented to his primary care physician 4 weeks before with upper respiratory symptoms and was treated with corticosteroids for presumed reactive airway disease. His respiratory symptoms resolved. One week after this presentation, he developed fever and right great toe pain and presented to an outside hospital. Inflammatory markers were elevated. MRI confirmed a diagnosis of osteomyelitis with associated periosteal abscess. He was treated with intravenous antibiotics and drainage of the abscess. Ten days after his discharge from the outside hospital, he developed fever and had increasing drainage of the toe and pain refractory to oral pain medications. He presented to our facility for further evaluation. Repeat MRI and inflammatory markers corroborated his worsening disease, and he was admitted to the hospital for intravenous antibiotics and underwent serial surgical debridement. He developed painful subcutaneous nodules on his lower extremities and was found to have lung abnormalities on chest radiograph. A multispecialty team collaborated in the management of this patient and unveiled a surprising diagnosis.

Skin and Soft Tissue Infections in Non-Human Immunodeficiency Virus Immunocompromised Hosts

Skin and soft tissue infections among the non-human immunodeficiency virus infected immunosuppressed population are a serious and growing concern. Many pathogens can cause cutaneous infections in these patients owing to the highly varied and profound immune deficits. Although patients can be infected by typical organisms, the diversity and antimicrobial-resistant nature of the organisms causing these infections result in significant morbidity and mortality. The diagnostic approach to these infections in immunocompromised hosts can differ dramatically depending on the potential causative organisms. An understanding of new immunosuppressive treatments and evolving antimicrobial resistance patterns are required to optimally manage these difficult cases.

Endemic mycoses: epidemiology and diagnostic strategies

INTRODUCTION

The global frequency of endemic mycoses has considerably increased, mainly due to environmental changes, population growth in endemic areas, and the increase in HIV-related immunosuppressed status. Among the most frequent endemic mycoses are coccidioidomycosis in semi-desert climates, and paracoccidioidomycosis, and histoplasmosis in tropical climates. The inoculum can enter the host through the airway or directly through the skin. Lymphatic and hematogenous spread may involve the skin.

AREAS COVERED

In this article, we provide up-to-date epidemiological and diagnostic data on major (histoplasmosis, paracoccidioidomycosis, coccidioidomycosis, blastomycosis) and minor (talaromycosis, adiaspiromycosis, emergomycosis) endemic mycoses.

EXPERT OPINION

Endemic mycoses include diseases with a localized endemic area, and a few of them converge. These mycoses all have in common the airway involvement and can cause pulmonary symptoms following initial asymptomatic infection. Among the risk groups to acquire these mycoses are travelers from endemic areas, archeologists, speleologists, and immigrants. Promising and useful diagnostic tools have been developed in endemic mycoses; however, most of them are not standardized or available in low-income countries.

The importance of skin exam in chronic pulmonary blastomycosis

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-Blastomycosis is a chronic granulomatous disease that usually starts as a pulmonary infection.

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-A high percentage of patients will develop a disseminated disease if the initial lung infection is left untreated.

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-Cutaneous blastomycosis is the most common extrapulmonary manifestation.

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-Definitive diagnosis requires direct visualization of the yeast at staining or positive fungal culture.

Cutaneous blastomycosis is the most common extrapulmonary manifestation of disseminated blastomycosis, a disease caused by Blastomyces dermatitidis, a dimorphic fungus endemic of North America. Initially, the organism enters the respiratory system by inhalation of the infectious conidia and produces an acute pulmonary infection that may eventually disseminate if it is left untreated. Blastomycosis may represent a diagnostic challenge and its definitive diagnosis requires direct visualization of the distinctive yeast or a positive fungal culture. The objective of this case report is to highlight the importance of the skin exam and tissue biopsy in the diagnosis of blastomycosis. We present a previously healthy patient with chronic pneumonia, evaluated at Pulmonary clinic with non-diagnostic thoracentesis and bronchoscopy, found to have disseminated blastomycosis after biopsy of a scalp lesion in Dermatology clinic.

Hemophagocytosis and Histoplasma-like fungal infection in 32 cats

Histoplasmosis is one of the most common systemic fungal diseases in cats from the United States. It commonly causes respiratory or disseminated disease and is often associated with one or more cytopenias. Here, we describe 32 cats in which a Histoplasma-like fungal infection was associated with concurrent hemophagia in at least one sample site, commonly spleen, bone marrow, liver, and/or lymph node. The degree of hemophagia was characterized as moderate or marked in the majority of cases, and in all cases, there was a predominance of phagocytized mature erythrocytes. A few cases also had macrophages with phagocytized erythroid precursors, platelets, and/or neutrophils. Complete blood count results were available for 25 cats, and cytopenias were common (20/25), including solitary anemia (10), anemia and thrombocytopenia (5), solitary neutropenia (2), pancytopenia (2), and anemia and neutropenia (1). Bone marrow samples were only available in a small subset of cases, preventing the further assessment of the causes of the cytopenias. Hemophagocytosis has been previously reported in cats with neoplastic diseases and a cat with calicivirus infection, and likely occurs with other conditions as well, such as hemorrhage or hemolysis. Results of this report suggest that systemic fungal disease is an additional differential to consider when there is hemophagia in a feline cytology sample.

Disseminated Blastomycosis in a Teenager Presenting with Pleural Effusion and Splenomegaly

BACKGROUND

Blastomycosis is caused by a fungus endemic to states and providences bordering the Lawrence Rivers and the Great Lakes. It can lead to significant pathology in both immunocompetent and immunocompromised hosts. This case report describes disseminated blastomycosis in an otherwise healthy 16-year-old patient.

CASE REPORT

A 16-year-old male presented with a chief complaint of flank pain. In the Emergency Department he described additional symptoms of emesis, cough, and weight loss. His vitals were appropriate; however, he had absent lung sounds in the left lower lung field, splenomegaly, a left thigh abscess, and lower-extremity edema. Imaging studies showed a left pleural effusion, mediastinal shift to the right, splenomegaly, a left psoas abscess, and undifferentiated bony involvement of L1 transverse process and the left 12th rib. Abscess cultures grew Blastomyces dermatitides. He was treated with amphotericin B, demonstrated clinical improvement, and was discharged on itraconazole. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: The case fatality rate of blastomycosis is estimated at between 4.3% and 6.4%. Patients with solid organ transplant and associated immune suppression had a mortality of 33-38%. Given the nonspecific nature of this condition, a high level of suspicion is required for diagnosis, and early diagnosis is essential, as end organ damage in disseminated disease can include high-severity illness, including acute respiratory distress syndrome and central nervous system dysfunction. If any patient presents with symptomatology involving both skin and pulmonary systems, blastomycosis must be entertained as a possible diagnosis. Prompt diagnosis and treatment will significantly improve morbidity and mortality.

Histoplasmosis in Africa: An emerging or a neglected disease?

Histoplasmosis in Africa has markedly increased since the advent of the HIV/AIDS epidemic but is under-recognised. Pulmonary histoplasmosis may be misdiagnosed as tuberculosis (TB). In the last six decades (1952-2017), 470 cases of histoplasmosis have been reported. HIV-infected patients accounted for 38% (178) of the cases. West Africa had the highest number of recorded cases with 179; the majority (162 cases) were caused by Histoplasma capsulatum var. dubuosii (Hcd). From the Southern African region, 150 cases have been reported, and the majority (119) were caused by H. capsulatum var. capsulatum (Hcc). There have been 12 histoplasmin skin test surveys with rates of 0% to 35% positivity. Most cases of Hcd presented as localised lesions in immunocompetent persons; however, it was disseminated in AIDS patients. Rapid diagnosis of histoplasmosis in Africa is only currently possible using microscopy; antigen testing and PCR are not available in most of Africa. Treatment requires amphotericin B and itraconazole, both of which are not licensed or available in several parts of Africa.

High Mortality and Coinfection in a Prospective Cohort of Human Immunodeficiency Virus/Acquired Immune Deficiency Syndrome Patients with Histoplasmosis in Guatemala

Histoplasmosis is one of the most common and deadly opportunistic infections among persons living with human immunodeficiency virus (HIV)/acquired immune deficiency syndrome in Latin America, but due to limited diagnostic capacity in this region, few data on the burden and clinical characteristics of this disease exist. Between 2005 and 2009, we enrolled patients ≥ 18 years of age with suspected histoplasmosis at a hospital-based HIV clinic in Guatemala City. A case of suspected histoplasmosis was defined as a person presenting with at least three of five clinical or radiologic criteria. A confirmed case of histoplasmosis was defined as a person with a positive culture or urine antigen test for Histoplasma capsulatum. Demographic and clinical data were also collected and analyzed. Of 263 enrolled as suspected cases of histoplasmosis, 101 (38.4%) were confirmed cases. Median time to diagnosis was 15 days after presentation (interquartile range [IQR] = 5-23). Crude overall mortality was 43.6%; median survival time was 19 days (IQR = 4-69). Mycobacterial infection was diagnosed in 70 (26.6%) cases; 26 (25.7%) histoplasmosis cases were coinfected with mycobacteria. High mortality and short survival time after initial symptoms were observed in patients with histoplasmosis. Mycobacterial coinfection diagnoses were frequent, highlighting the importance of pursuing diagnoses for both diseases.

Clinical Manifestations and Treatment of Blastomycosis

The causal agents of blastomycosis, Blastomyces dermatitidis and Blastomyces gilchristii, belong to a group of thermally dimorphic fungi that can infect healthy and immunocompromised individuals. Following inhalation of mycelial fragments and spores into the lungs, Blastomyces spp convert into pathogenic yeast and evade host immune defenses to cause pneumonia and disseminated disease. The clinical spectrum of pulmonary blastomycosis is diverse. The diagnosis of blastomycosis requires a high degree of clinical suspicion and involves culture-based and non-culture-based fungal diagnostic tests. The site and severity of infection, and the presence of underlying immunosuppression or pregnancy, influence the selection of antifungal therapy.

Card9- and MyD88-Mediated Gamma Interferon and Nitric Oxide Production Is Essential for Resistance to Subcutaneous Coccidioides posadasii Infection

Coccidioidomycosis is a potentially life-threatening respiratory disease which is endemic to the southwestern United States and arid regions of Central and South America. It is responsible for approximately 150,000 infections annually in the United States alone. Almost every human organ has been reported to harbor parasitic cells of Coccidioides spp. in collective cases of the disseminated form of this mycosis. Current understanding of the mechanisms of protective immunity against lung infection has been largely derived from murine models of pulmonary coccidioidomycosis. However, little is known about the nature of the host response to Coccidioides in extrapulmonary tissue. Primary subcutaneous coccidioidal infection is rare but has been reported to result in disseminated disease. Here, we show that activation of MyD88 and Card9 signal pathways are required for resistance to Coccidioides infection following subcutaneous challenge of C57BL/6 mice, which correlates with earlier findings of the protective response to pulmonary infection. MyD88(-/-) andCard9(-/-) mice recruited reduced numbers of T cells, B cells, and neutrophils to the Coccidioides-infected hypodermis com pared to wild-type mice; however, neutrophils were dispensable for resistance to skin infection. Further studies have shown that gamma interferon (IFN-γ) production and activation of Th1 cells characterize resistance to subcutaneous infection. Furthermore, activation of a phagosomal enzyme, inducible nitric oxide synthase, which is necessary for NO production, is a requisite for fungal clearance in the hypodermis. Collectively, our data demonstrate that MyD88- and Card9-mediated IFN-γ and nitric oxide production is essential for protection against subcutaneous Coccidioides infection.

Blastomycosis

Blastomycosis is an endemic fungal infection due to Blastomyces dermatitidis that most commonly causes pneumonia; but the organism can disseminate to any organ system, most commonly the skin, bones/joints, and genitourinary tract. Both immunocompetent and immunocompromised persons can be infected, but more severe disease occurs in the immunocompromised. Blastomycosis can be diagnosed by culture, direct visualization of the yeast in affected tissue, and/or antigen testing. Treatment course and duration depend on severity of illness. For mild to moderate pulmonary disease the treatment is itraconazole. For severe blastomycosis, lipid formulation amphotericin B is given, followed by step-down therapy with itraconazole.

Histoplasmosis in HIV-Infected Patients: A Review of New Developments and Remaining Gaps

Histoplasma capsulatum is responsible for histoplasmosis, a fungal disease with worldwide distribution that can affect both immunocompromised and imunocompetent individuals. During the highly active antiretroviral therapy (HAART) era, morbidity and mortality due to histoplasmosis remained a public heatlh problem in low-income and high-income countries. The true burden of HIV-associated histoplasmosis is either not fully known or neglected since it is not a notifiable disease. Progress has been made in DNA patterns of strains and understanding of pathogenesis, and hopefully these will help identify new therapeutic targets. Unfortunately, histoplasmosis is still widely mistaken for multidrug-resistant tuberculosis, leading to numerous avoidable deaths, even if they are easily distinguishable. The new diagnostic tools and therapeutics developments have still not been made available in most endemic regions. Still, recent developments are promising because of their good clinical characteristics and also because they will be commercially available and affordable. This review of published data and gaps may help define and guide future research.