Histoplasma capsulatum endocarditis: multicenter case series with review of current diagnostic techniques and treatment

Infectious factors in myocarditis: a comprehensive review of common and rare pathogens

BACKGROUND

Myocarditis is a significant health threat today, with infectious agents being the most common cause. Accurate diagnosis of the etiology of infectious myocarditis is crucial for effective treatment.

MAIN BODY

Infectious myocarditis can be caused by viruses, prokaryotes, parasites, and fungi. Viral infections are typically the primary cause. However, some rare opportunistic pathogens can also damage heart muscle cells in patients with immunodeficiencies, neoplasms and those who have undergone heart surgery.

CONCLUSIONS

This article reviews research on common and rare pathogens of infectious myocarditis, emphasizing the complexity of its etiology, with the aim of helping clinicians make an accurate diagnosis of infectious myocarditis.

Endemic Fungal Infective Endocarditis Caused by Coccidioides, Blastomyces and Histoplasma Species in the United States

We describe a recent case of Coccidioides bioprosthetic aortic valve infective endocarditis successfully managed at our institution. This led us to perform a literature review of endemic fungal infective endocarditis in the United States caused by Coccidioides, Blastomyces, and Histoplasma. Symptoms preceded infective endocarditis diagnosis by several months. Patients with Coccidioides and Blastomyces infective endocarditis were younger with fewer comorbid conditions. Valvular involvement was relatively uncommon in Blastomyces infective endocarditis (27%). Fungemia was noted in patients with infective endocarditis due to Histoplasma (30%) and Coccidioides (18%). Mortality rates for infective endocarditis were high (Histoplasma, 46%; Coccidioides, 58%; Blastomyces, 80%); infective endocarditis was commonly diagnosed post-mortem (Coccidioides, 58%; Blastomyces, 89%). Most surviving patients with infective endocarditis (Histoplasma, 79%; Coccidioides, 80%) underwent valve surgery along with prolonged antifungal therapy. The two surviving patients with Blastomyces infective endocarditis received antifungal therapy without surgery.

Pulmonary Histoplasmosis Complicated by Nonvalvular Right Ventricular Wall Histoplasma capsulatum Endocarditis

Histoplasmosis is commonly a self-limited fungal disease that primarily affects the lung and reticuloendothelial system. Cardiac involvement by histoplasmosis is uncommon. In this report, we provide a detailed description of severe pulmonary histoplasmosis complicated by the disease involvement of the free wall of the right ventricle. A 55-year-old female presented with cough, fevers, dyspnea, and 30-pound unintentional weight loss in 6 months. Her past medical history was significant for supraventricular tachycardia with permanent pacemaker implantation. Imaging studies revealed an intracardiac mass accompanied by mediastinal lymphadenopathy and bilateral lung nodules. Endobronchial ultrasound-guided transbronchial needle aspiration of station 4R lymph nodes revealed numerous yeast forms, morphologically consistent with Histoplasma capsulatum. The diagnosis was further corroborated by the elevated titers of serum antibodies against Histoplasma capsulatum. The right ventricular mass debulking with biopsy showed necrotizing granulomatous inflammation involving nonvalvular endocardium and myocardium of the free wall of the right ventricle. The report documents an unusual presentation of pulmonary histoplasmosis accompanied by nonvalvular endocarditis and suggests a possible association between the site of the cardiac infection and the presence of a permanent intravascular pacer device.

HISTOPLASMA CAPSULATUM PACEMAKER-RELATED ENDOCARDITIS PRESENTING AS ENDOGENOUS ENDOPHTHALMITIS

BACKGROUND/PURPOSE

To report a unique case of pacemaker-related infective endocarditis manifesting as endogenous endophthalmitis with chorioretinitis secondary to Histoplasma capsulatum.

METHODS

Case report.

RESULTS

A 75-year-old man was diagnosed with blood culture-negative infective endocarditis and was admitted with deteriorating vision and ocular inflammation. Examination of the eye indicated significant vitreous inflammation and retinitis. Vitreous cultures were negative, but universal fungal polymerase chain reaction of the vitreous fluid was positive for H. capsulatum. Histopathology of the fibrous cuff around the extracted right atrial lead demonstrated hyphal and yeast forms and polymerase chain reaction of this material identified H. capsulatum. Despite aggressive antifungal and surgical treatment, the eye became phthisical.

CONCLUSION

We highlight the importance of considering H. capsulatum in the differential diagnosis of endogenous endophthalmitis, particularly among patients from endemic areas who present with possible endovascular infection.

A Complex Case of Histoplasmosis in an Immunocompromised Patient: Diagnostic Challenges, Multidisciplinary Collaboration, and Environmental Factors

Histoplasmosis is a systemic fungal infection caused by Histoplasma capsulatum, known for its protean clinical manifestations that often pose diagnostic challenges. Immunocompromised patients, such as those on immunosuppressive therapies or with HIV/AIDS, are particularly susceptible to severe forms of the disease. We present a case of a 55-year-old female with a complex medical history, including a renal transplant, who developed fever, malaise, nausea, and vomiting after a month-long stay in Panama. The patient's history included exposure to a bird with apparent infection and mold in her home. Her clinical presentation featured acute kidney injury, elevated liver enzymes, acalculous cholecystitis, and lung nodules. This intricate constellation of symptoms underscores the diverse nature of histoplasmosis presentations and its potential to mimic other diseases. The patient underwent a stepwise diagnostic approach involving imaging, microbiological tests, and multidisciplinary consultations. The positive Fungitell assay, Histoplasma capsulatum detection in urine, and identification of scattered subcentimeter lung nodules confirmed the diagnosis. This case underscores the significance of considering endemic areas, environmental exposures, and atypical clinical features in immunocompromised patients. The multidisciplinary approach facilitated appropriate management and treatment initiation with liposomal amphotericin B, highlighting the importance of collaboration among various medical specialties in complex cases. As such, this case report emphasizes the complexity of diagnosing and managing histoplasmosis in immunocompromised individuals and highlights the need for a comprehensive evaluation of atypical presentations.

Fungal Endocarditis: Pathophysiology, Epidemiology, Clinical Presentation, Diagnosis, and Management

Fungal endocarditis accounts for 1% to 3% of all infective endocarditis cases, is associated with high morbidity and mortality (>70%), and presents numerous challenges during clinical care. Candida spp. are the most common causes of fungal endocarditis, implicated in over 50% of cases, followed by Aspergillus and Histoplasma spp. Important risk factors for fungal endocarditis include prosthetic valves, prior heart surgery, and injection drug use. The signs and symptoms of fungal endocarditis are nonspecific, and a high degree of clinical suspicion coupled with the judicious use of diagnostic tests is required for diagnosis. In addition to microbiological diagnostics (e.g., blood culture for Candida spp. or galactomannan testing and PCR for Aspergillus spp.), echocardiography remains critical for evaluation of potential infective endocarditis, although radionuclide imaging modalities such as 18F-fluorodeoxyglucose positron emission tomography/computed tomography are increasingly being used. A multimodal treatment approach is necessary: surgery is usually required and should be accompanied by long-term systemic antifungal therapy, such as echinocandin therapy for Candida endocarditis or voriconazole therapy for Aspergillus endocarditis.

Unusual Presentation of Disseminated Histoplasmosis in an Immunocompetent Host

Histoplasmosis, a fungal infection caused by the inhalation of Histoplasma capsulatum conidia spores, has been shown to cause disseminated disease in immunocompromised individuals. Disseminated histoplasmosis manifests as multi-system involvement including pulmonary and/or neurological disease. Imaging findings, such as pulmonary focal infiltrates, cavitary nodules, mediastinal, and hilar lymphadenopathy, are common. Here, we report a rare case of disseminated histoplasmosis in a 58-year-old immunocompetent male with no occupational exposure. This patient presented with primary adrenal insufficiency, and a subsequent CT-guided biopsy of the adrenal gland was performed and revealed numerous spores containing Histoplasma capsulatum. This patient also suffered from numerous pulmonary and neurological derangements, which are likely sequelae of the disseminated fungal infection. Ultimately, the patient succumbed to their illness and died. Preventing such outcomes relies on early detection and prompt management, which are crucial in treating disseminated histoplasmosis. Increased awareness of atypical presentations can enhance patient outcomes and alleviate the impact of this severe fungal infection. This case not only underscores the importance of considering disseminated histoplasmosis in an immunocompetent patient presenting with unexplained weight loss and adrenal insufficiency but also contributes to the limited literature on disseminated histoplasmosis in immunocompetent individuals.

Four decades of experience of prosthetic valve endocarditis reflect a high variety of diverse pathogens

Prosthetic valve endocarditis (PVE) remains a serious condition with a high mortality rate. Precise identification of the PVE-associated pathogen/s and their virulence is essential for successful therapy, and patient survival. The commonly described PVE-associated pathogens are staphylococci, streptococci and enterococci, with Staphylococcus aureus being the most frequently diagnosed species. Furthermore, multi-drug resistance pathogens are increasing in prevalence, and continue to pose new challenges mandating a personalized approach. Blood cultures in combination with echocardiography are the most common methods to diagnose PVE, often being the only indication, it exists. In many cases, the diagnostic strategy recommended in the clinical guidelines does not identify the precise microbial agent and to frequently, false negative blood cultures are reported. Despite the fact that blood culture findings are not always a good indicator of the actual PVE agent in the valve tissue, only a minority of re-operated prostheses are subjected to microbiological diagnostic evaluation. In this review, we focus on the diversity and the complete spectrum of PVE-associated bacterial, fungal and viral pathogens in blood, and prosthetic heart valve, their possible virulence potential, and their challenges in making a microbial diagnosis. We are curious to understand if the unacceptable high mortality of PVE is associated with the high number of negative microbial findings in connection with a possible PVE. Herein, we discuss the possibilities and limits of the diagnostic methods conventionally used and make recommendations for enhanced pathogen identification. We also show possible virulence factors of the most common PVE-associated pathogens and their clinical effects. Based on blood culture, molecular biological diagnostics, and specific valve examination, better derivations for the antibiotic therapy as well as possible preventive intervention can be established in the future.

Rare case of Histoplasma capsulatum endocarditis in a patient with a prosthetic valve

BACKGROUND

Diagnosis of fungal endocarditis can be challenging, especially among cases with negative blood culture results. Of fungal endocarditis cases, Histoplasma capsulatum constitutes an even smaller proportion with ∼58 prior cases reported. Due to the rarity of histoplasmosis endocarditis and thus limited data, there is no current diagnostic guideline for testing within culture negative infective endocarditis.

CASE SUMMARY

Our patient was a 58-year-old female presenting with worsening dyspnoea, hypotension, and near-syncope. In this case report, we depict the clinical presentation and diagnosis of H. capsulatum endocarditis in a female patient with a prosthetic aortic valve and negative blood cultures. We further demonstrate the rising risk of fungal endocarditis with use of external devices.

DISCUSSION

Despite the rarity of fungal endocarditis, there has been a recent upward trend in infections given the rising use of external devices, greater number of immunocompromised patients, and rising rates of intravenous drug use. Recently, more cases of fungal endocarditis have been occurring in patients with prosthetic valves compared to native. Although H. capsulatum constitutes a smaller proportion of fungal endocarditis cases, patients with appropriate risk factors and those who have been exposed to at-risk areas such as the Ohio and Mississippi River valleys, may benefit from further evaluation.

Histoplasma capsulatum culture-negative prosthetic valve endocarditis presenting as a cystic mass

A 58-year-old immunocompetent patient with previous prosthetic valve presented with chest pain, constitutional symptoms and septic shock. Blood cultures and transthoracic echocardiogram were negative, but the patient was initiated on broad spectrum antibiotics due to high clinical suspicions of infective endocarditis. The patient received a transoesophageal echocardiogram revealing a cystic bioprosthetic valve lesion. Culture-negative endocarditis workup identified active disseminated histoplasmosis with likely Histoplasma endocarditis. A multidisciplinary discussion was held, and the patient was deemed high-risk for a third re-do open heart surgery. He was treated medically with anti-fungal treatment with good clinical recovery.

Ischemic brain infarcts and vasculitis in histoplasmosis of the central nervous system: A case report and review of the literature

Histoplasmosis is one of the most common endemic mycoses affecting immunocompromised individuals in the United States and Latin America. Involvement of the central nervous system carries higher mortality rates and worse prognosis, given its resemblance to stroke, vasculitis, and meningitis of other etiologies. The diagnosis is challenging, due to its subtle clinical presentation and the poor sensitivity of the cerebrospinal fluid culture. Herein the authors present a case of a middle-aged man with HIV, who presented with intermittent headaches exacerbated by an oculomotor nerve palsy, concerning for acute stroke. A diagnosis of central nervous system histoplasmosis was made, and his neurological deficits subsided after initiation of treatment. The stroke-like syndrome in this scenario may be secondary to granulomatous vasculitis of small caliber cerebral blood vessels. Histoplasmosis of the central nervous system remains a challenging diagnosis, which requires a high index of suspicion by the clinician for an early institution of therapy in order to improve outcomes.

Post-treatment bacterial endocarditis mimicking fungal organisms: a morphologic comparison and tips for avoiding this diagnostic pitfall

BACKGROUND

Histopathologic differentiation of bacterial endocarditis from yeast-like fungal endocarditis is usually straightforward; however, an underappreciated phenomenon is the effect of antimicrobial therapy on bacterial size, shape and septa (cross-wall) formation resulting in bacterial forms that mimic yeast-like fungi. In this article we illustrate the alterations that occur in antibiotic-treated Staphylococcus aureus endocarditis and compare these changes to histopathologic findings in unaltered S. aureus and Histoplasma endocarditis, respectively.

METHODS

Resected valves from three cases of endocarditis were compared based on the type ofinflammatory reaction, organism morphology and culture results. Case 1 was S. aureus endocarditis initially misclassified as Histoplasma due to its atypical morphologic and histopathologic features. The two cases included for comparison were an S. aureus endocarditis with more classic features and an Histoplasma capsulatum endocarditis. Hematoxylin and eosin (H&E), Gram, periodic acid Schiff (PAS), Gomori-Grocott methenamine silver stains (GMS), and culture results were compared in all cases. Molecular and immunohistochemistry tests were used for confirmation of first case. High power oil-immersion was used to visualize organisms' characteristics in all three cases.

RESULTS

Case 1 and Case 3 (Histoplasma-infected valves) had fibrinous exudates with scattered macrophages. The microorganisms observed in the first case of methicillin-sensitive S. aureus (MSSA) were ∼ 2-3 μm by GMS stain and had prominent septations. Histoplasma yeast were round to oval, ∼ 3-4 μm in size and demonstrated budding. S. aureus without alterations were round, ∼ 1 μm in size, and lacked prominent septations. Necrotizing purulent inflammation was present in the unaltered case of MSSA. The MSSA case with alterations from antibiotic treatment did not stain well with the Gram stain and organisms were best visualized with the PAS and GMS stains.

CONCLUSIONS

Antibiotic therapy for bacterial endocarditis can alter the inflammatory reaction to infection, bacterial size, septa formation, and staining characteristics. Knowledge of these therapy-related effects and use of high-power magnification helps to avoid misclassification as yeast-like fungi.

Native vs Prosthetic Valve Histoplasma capsulatum Infective Endocarditis: A Case Report and Systemic Literature Review Comparing Patient Presentation, Treatment Modalities, Clinical Outcomes, and Diagnostic Laboratory Testing

Histoplasma capsulatum is a rare cause of fungal endocarditis that affects both native and prosthetic valves. It is associated with a high mortality rate if not diagnosed early and treated with a combination of antifungal therapy and surgical intervention. We present a case of a 47-year-old man with histoplasmosis infective endocarditis. He was successfully treated with antifungal therapy and surgical replacement of the infected bioprosthetic aortic valve. Our systemic literature review includes 52 articles encompassing 60 individual cases of H. capsulatum infective endocarditis from 1940 to 2020. Patient presentations, diagnostic laboratory testing accuracy, treatment modalities, and patient outcomes comparing and contrasting native and prosthetic valve infection are described.

Native Valve Infective Endocarditis Caused by Histoplasma capsulatum in an Immunocompetent Host: The First Case in Asia and Literature Review in Asia and Australia

Background

Infective endocarditis caused by the dimorphic fungus Histoplasma capsulatum is extremely rare, occurring predominantly in individuals with prosthetic heart valves and HIV infection. To our knowledge, no case of H. capsulatum native valve endocarditis has been reported in Asia. Methodology. A descriptive study was carried out at King Chulalongkorn Memorial Hospital, Bangkok, Thailand, in 2020.

Results

A previously healthy 34-year-old man developed fever, umbilicated skin lesions, oral ulcers, hoarseness of voice, severe weight loss, and progressive dyspnea over the course of one week. Facial umbilicated papules, nodular ulcers in his tongue and palate, a diastolic rumbling murmur at the mitral valve, diffuse fine crackles in both lungs, and engorged neck veins were detected during the examination. Skin scraping of the facial lesion revealed both extracellular and intracellular yeasts with buddings, 2–4 μm in size on Wright's stain. Transthoracic echocardiography demonstrated a left ventricular ejection fraction of 54 percent, severe rheumatic mitral stenosis, and multiple oscillating masses in the anterior mitral valve leaflet ranging in dimension from 1.5 to 2.4 cm. The HIV antibody test was negative. H. capsulatum endocarditis was diagnosed, and liposomal amphotericin B was administered. Due to cardiogenic shock, emergency open-heart surgery was conducted one day after admission. However, he died of multiorgan failure four days after the operation. The skin and vegetation cultures finally grew H. capsulatum after 1 week of incubation.

Conclusions

To date, there has been handful of cases of H. capsulatum native valve endocarditis in non-HIV-infected patients. We report herein the first case in Thailand. Umbilicated skin lesions, especially combined with oral mucosal lesions, are a clinical clue that leads to the correct diagnosis of the causative organism.

Heat Shock Protein 60, Insights to Its Importance in Histoplasma capsulatum: From Biofilm Formation to Host-Interaction

Heat shock proteins (Hsps) are among the most widely distributed and evolutionary conserved proteins, acting as essential regulators of diverse constitutive metabolic processes. The Hsp60 of the dimorphic fungal Histoplasma capsulatum is the major surface adhesin to mammalian macrophages and studies of antibody-mediated protection against H. capsulatum have provided insight into the complexity involving Hsp60. However, nothing is known about the role of Hsp60 regarding biofilms, a mechanism of virulence exhibited by H. capsulatum. Considering this, the present study aimed to investigate the influence of the Hsp60 on biofilm features of H. capsulatum. Also, the non-conventional model Galleria mellonella was used to verify the effect of this protein during in vivo interaction. The use of invertebrate models such as G. mellonella is highly proposed for the evaluation of pathogenesis, immune response, virulence mechanisms, and antimicrobial compounds. For that purpose, we used a monoclonal antibody (7B6) against Hsp60 and characterized the biofilm of two H. capsulatum strains by metabolic activity, biomass content, and images from scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). We also evaluated the survival rate of G. mellonella infected with both strains under blockage of Hsp60. The results showed that mAb 7B6 was effective to reduce the metabolic activity and biomass of both H. capsulatum strains. Furthermore, the biofilms of cells treated with the antibody were thinner as well as presented a lower amount of cells and extracellular polymeric matrix compared to its non-treated controls. The blockage of Hsp60 before fungal infection of G. mellonella larvae also resulted in a significant increase of the larvae survival compared to controls. Our results highlight for the first time the importance of the Hsp60 protein to the establishment of the H. capsulatum biofilms and the G. mellonella larvae infection. Interestingly, the results with Hsp60 mAb 7B6 in this invertebrate model suggest a pattern of fungus-host interaction different from those previously found in a murine model, which can be due to the different features between insect and mammalian immune cells such as the absence of Fc receptors in hemocytes. However further studies are needed to support this hypothesis

Current and New Perspectives in the Diagnosis of Blastomycosis and Histoplasmosis

The diagnosis of blastomycosis and histoplasmosis can be difficult for clinicians who rarely see infections caused by these environmentally restricted dimorphic fungi. Historically, the diagnosis of blastomycosis has been established by culture and sometimes by histopathologic identification. Currently, antigen detection in urine and serum has been shown to aid in the rapid diagnosis of blastomycosis, and newer antibody assays are likely to contribute to our diagnostic capability in the near future. The gold standard for the diagnosis of histoplasmosis has been culture of the organism from involved tissues, aided in some patients by histopathological verification of the typical yeast forms in tissues. Antigen detection has contributed greatly to the ability of clinicians to rapidly establish the diagnosis of histoplasmosis, especially in severely ill and immunocompromised patients, and antibody testing for Histoplasma capsulatum provides important adjunctive diagnostic capability for several forms of both acute and chronic histoplasmosis. For both of these endemic mycoses, novel molecular tests are under active investigation, but remain available in only a few reference laboratories. In this review, we provide a synopsis of diagnostic test options that aid in establishing whether a patient has blastomycosis or histoplasmosis.

HIV-Associated Histoplasmosis: Current Perspectives

Histoplasmosis is an endemic mycosis caused by Histoplasma capsulatum. Infection develops by inhalation of microconidia from environmental sites inhabited by birds and bats. Disseminated disease is the usual presentation due to impaired cellular immunity. Common clinical manifestations include fever, fatigue, malaise, anorexia, weight loss, and respiratory symptoms. Histoplasma antigen detection is the most sensitive method for diagnosis. The sensitivity of the MVista^® Quantitative Histoplasma antigen enzyme immunoassay is 95-100% in urine, over 90% in serum and bronchoalveolar lavage (BAL) antigen and 78% in cerebral spinal fluid (CSF). A proven diagnosis can be established by culture or pathology with sensitivities between 70% and 80%. The sensitivity of antibody detection by immunodiffusion or complement fixation was between 60% and 70%. Diagnosis using molecular methods has not been adequately validated for implementation and FDA cleared assays are unavailable. Liposomal amphotericin B should be used for 1-2 weeks followed by itraconazole for at least one year until CD4 counts are above 150 cells/mm3, HIV viral load is below 400 copies/mL and Histoplasma urine antigen is negative. Serum itraconazole level should be monitored to avoid drug toxicity. Antigen should be measured periodically to establish that treatment is effective and to assist in identifying relapse. The incidence of immune reconstitution inflammatory syndrome is low but it must be considered in patients who are thought to be failing antifungal treatment as it does not respond to changing antifungal agents but rather to initiation of corticosteroid therapy. In this review, we discuss pathogenesis, clinical manifestations, diagnosis and treatment based on personal experience and relevant publications.

A case report of Histoplasma capsulatum prosthetic valve endocarditis: an extremely rare presentation with characteristic findings

Background 

Histoplasma capsulatum is an extremely rare cause of prosthetic valve endocarditis (PVE) and can present with non-specific symptoms leading to a delay in diagnosis with unfavourable outcomes.

Case summary 

A 65-year-old male patient with a history of a bioprosthetic aortic valve replacement and non-obstructive coronary artery disease was admitted for altered mentation, failure to thrive, and a 20-pound unintentional weight loss over the past 4 months. Upon examination, he was lethargic but afebrile and haemodynamically stable. A late peaking ejection murmur was heard on exam. Skin exam was significant for embolic phenomenon involving the extremities. Inflammatory markers and serum calcium were elevated. A bedside echocardiogram showed severe obstruction across the aortic valve prosthesis. Two years prior, he had an echocardiogram with a normal functioning prosthesis. Routine blood cultures were negative and serologic screening was unrevealing. Urine Histoplasma antigen screen was positive on hospital day 3 and on hospital day 10, fungal blood cultures were positive for H. capsulatum. Unfortunately, the patient died shortly afterwards as a result of multiorgan failure from embolic manifestations of the infection.

Discussion 

Based on our patient's findings and those of previously reported cases in the literature, H. capsulatum PVE should be strongly considered in patients from endemic areas with non-specific symptoms and negative routine blood cultures.

Diagnosis and treatment of histoplasmosis in solid organ transplant patients

PURPOSE OF REVIEW

Unlike immunocompetent hosts, solid organ transplant (SOT) recipients with posttransplant histoplasmosis (PTH) often present with disseminated disease and have an attributable mortality of approximately 10%. In this review, we discuss currently available diagnostic tests and treatment strategies in PTH.

RECENT FINDINGS

None of the available tests have a 100% diagnostic accuracy. Histoplasma antigen assays are the most sensitive commercially available tests. However, crossreactivity of histoplasma antigen with aspergillus galactomannan and false positive histoplasma antigen tests because of rabbit antithymocyte globulin may cause difficulty in interpreting positive test results in transplant recipients. Molecular assays such as amplification and sequencing of 'panfungal' portions of the 28S ribosomal RNA from clinical specimens appear to be promising.Lipid formulations of amphotericin B and itraconazole are the drugs of choice in the treatment of PTH. Other extended spectrum azoles also appear to be effective, but, like itraconazole, problems with drug interactions and prolongation of the QTc interval (except for isavuconazole, which shortens the QTc interval) remain. Mycophenolate therapy is associated with severe disease and should be stopped during active disease and, if feasible, calcineurin inhibitors and steroids should be reduced.

SUMMARY

A combination of various tests (culture, antigen tests, nucleic amplification tests, etc.) should be used to optimize diagnostic yield. The role of unbiased next generation sequencing for early diagnosis and newer azoles in the treatment needs to be further explored.

Histoplasma Endocarditis Diagnosed by Thrombus Aspiration

Negative cultures in endocarditis often lead to delays in targeted life-saving therapies. We present the case of a 68-year-old man who presented with culture-negative endocarditis, which was complicated by coronary embolization resulting in anterior ST-elevation myocardial infarction (STEMI). Aspiration thrombectomy led to the diagnosis of fungal endocarditis, one of the most serious causes of culture-negative presentation.

Asymptomatic Histoplasma Pylephlebitis in an Orthotopic Liver Transplant Recipient: A Case Report and Literature Review

Histoplasma capsulatum is one of the most common pathogenic dimorphic fungi in Thailand. Its usual clinical syndrome is progressive disseminated histoplasmosis, whereas isolated hepatic histoplasmosis is extremely rare. Here, we report the world's first reported case of hepatic histoplasmosis with pylephlebitis in a 45-year-old Thai male who underwent orthotopic liver transplantation due to hepatitis B cirrhosis. Histopathology of the recipient's liver showed infiltration of fungal organisms in portal vein and hepatic granulomas. Serum H. capsulatum antibody was positive, and molecular identification from the liver revealed the DNA of H. capsulatum.

Histoplasmosis Myocarditis in an Immunocompetent Host After a Recreational Mud Run

Mud runs are an increasingly popular recreational fitness activity across the United States, combining a running race through an obstacle course with submersion in mud. Recent reports estimate 4 million people have participated in these types of events over the last 5 years. We describe an atypical case of myocarditis and multiorgan failure from disseminated histoplasmosis in a previously healthy pediatric patient, likely acquired during participation in a mud run. Although cases of histoplasmosis-associated endocarditis and pericarditis have been reported in the literature, cases of histoplasmosis myocarditis are rare.

Diagnostic Importance of Hyphae on Heart Valve Tissue in Histoplasma Endocarditis and Treatment With Isavuconazole

A patient who never resided in an endemic area for dimorphic fungi was diagnosed with Histoplasma capsulatum endocarditis. His diagnosis was suggested by yeast and hyphae on cardiac valve tissue pathology. Isavuconazole was an optimal therapeutic option due to renal dysfunction and anticoagulation with warfarin for mechanical valve replacement.

Nonculture Diagnostics in Fungal Disease

Fungal diagnostics that utilize antibody, antigen or nucleic acid detection offer several advantages that supplement traditional culture-based methods. As a group, nonculture assays can help identify patients with invasive fungal infection (IFI) sooner than is possible with culture, are often more sensitive, and can be used to guide early interventions. Challenges associated with these techniques include the possibility for contamination or cross-reactivity as well as the potential for false negative tests. This review summarized the test characteristics and clinical utility of nonculture-based laboratory methods.

Fungal Endocarditis: Update on Diagnosis and Management

Fungal endocarditis is an extremely debilitating disease associated with high morbidity and mortality. Candida spp. are the most common isolated organisms in fungal endocarditis. It is most prevalent in patients who are immunosuppressed and intravenous drug users. Most patients present with constitutional symptoms, which are indistinguishable from bacterial endocarditis, hence a high index of suspicion is required for pursuing diagnosis. Diagnosis of fungal endocarditis can be very challenging: most of the time, blood cultures are negative or take a long time to yield growth. Fungal endocarditis mandates an aggressive treatment strategy. A medical and surgical combined approach is the cornerstone of therapy.

Filamentous Fungi

Filamentous mycoses are often associated with significant morbidity and mortality. Prompt diagnosis and aggressive treatment are essential for good clinical outcomes in immunocompromised patients. The host immune response plays an essential role in determining the course of exposure to potential fungal pathogens. Depending on the effectiveness of immune response and the burden of organism exposure, fungi can either be cleared or infection can occur and progress to a potentially fatal invasive disease. Nonspecific cellular immunity (i.e., neutrophils, natural killer [NK] cells, and macrophages) combined with T-cell responses are the main immunologic mechanisms of protection. The most common potential mold pathogens include certain hyaline hyphomycetes, endemic fungi, the Mucorales , and some dematiaceous fungi. Laboratory diagnostics aimed at detecting and differentiating these organisms are crucial to helping clinicians make informed decisions about treatment. The purpose of this chapter is to provide an overview of the medically important fungal pathogens, as well as to discuss the patient characteristics, antifungal-therapy considerations, and laboratory tests used in current clinical practice for the immunocompromised host.

Antineutrophil Cytoplasmic Antibodies Associated With Infective Endocarditis

To determine the prevalence of antineutrophil cytoplasmic antibodies (ANCA) in patients with infective endocarditis (IE) in internal medicine; and to compare clinical and biochemical features and outcome between patients exhibiting IE with and without ANCA.Fifty consecutive patients with IE underwent ANCA testing. The medical records of these patients were reviewed.Of the 50 patients with IE, 12 exhibited ANCA (24%). ANCA-positive patients with IE exhibited: longer duration between the onset of first symptoms and IE diagnosis (P = 0.02); and more frequently: weight loss (P = 0.017) and renal impairment (P = 0.08), lower levels of C-reactive protein (P = 0.0009) and serum albumin (P = 0.0032), involvement of both aortic and mitral valves (P = 0.009), and longer hospital stay (P = 0.016). Under multivariate analysis, significant factors for ANCA-associated IE were: longer hospital stay (P = 0.004), lower level of serum albumin (P = 0.02), and multiple valve involvement (P = 0.04). Mortality rate was 25% in ANCA patients; death was because of IE complications in all these patients.Our study identifies a high prevalence of ANCA in unselected patients with IE in internal medicine (24%). Our findings further underscore that ANCA may be associated with a subacute form of IE leading to multiple valve involvement and more frequent renal impairment. Because death was due to IE complications in all patients, our data suggest that aggressive therapy may be required to improve such patients' outcome.

Severe pulmonic valve regurgitation due to histoplasma endocarditis

A 67-year-old man with myelodysplastic syndrome, disseminated histoplasmosis, and mitral valve replacement presented with dyspnea and peripheral edema. Transthoracic echocardiography demonstrated abnormal pulmonic valve with possible vegetation. Color flow imaging showed laminar flow from main pulmonary artery into right ventricular outflow tract (RVOT) in diastole. The continuous wave Doppler signal showed dense diastolic envelope with steep deceleration slope. These findings were consistent with severe pulmonic valve regurgitation, possibly due to endocarditis. Transesophageal echocardiography demonstrated an echodense mass attached to the pulmonic valve. The mitral valve bioprosthesis appeared intact. Bacterial and fungal blood cultures were negative; however, serum histoplasma antigen was positive. At surgery, the valve appeared destroyed by vegetations. Gomori methenamine silver-stains showed invasive fungal hyphae and yeast consistent with a dimorphic fungus. Valve cultures grew one colony of filamentous fungus. Itraconazole was continued based on expert infectious diseases diagnosis. After surgery, dyspnea and ankle edema resolved. To the best of our knowledge, histoplasma endocarditis of pulmonic valve has not been previously reported. Isolated pulmonic valve endocarditis is rare, accounting for about 2% of infectious endocarditis (IE) cases. Fungi account for about 3% of cases of native valve endocarditis. Characterization of pulmonary valve requires thorough interrogation with 2D and Doppler echocardiography techniques. Parasternal RVOT view allowed visualization of the pulmonary valve and assessment of regurgitation severity. As an anterior structure, it may be difficult to image with transesophageal echocardiography. Mid-esophageal right ventricular inflow-outflow view clearly showed the pulmonary valve and vegetation.

LEARNING POINTS

Identification and characterization of pulmonary valve abnormalities require thorough interrogation with 2D and Doppler echocardiography techniques.Isolated pulmonary valve IE is rare and requires high index of suspicion. Histoplasma capsulatum IE is rare and requires high index of suspicion.