Histoplasmosis and Blastomycosis in Solid Organ Transplant Recipients

Pneumocystis jirovecii Pneumonia after Heart Transplantation: Two Case Reports and a Review of the Literature

Post-transplant Pneumocystis jirovecii pneumonia (PcP) is an uncommon but increasingly reported disease among solid organ transplantation (SOT) recipients, associated with significant morbidity and mortality. Although the introduction of PcP prophylaxis has reduced its overall incidence, its prevalence continues to be high, especially during the second year after transplant, the period following prophylaxis discontinuation. We recently described two cases of PcP occurring more than one year after heart transplantation (HT) in patients who were no longer receiving PcP prophylaxis according to the local protocol. In both cases, the disease was diagnosed following the diagnosis of a viral illness, resulting in a significantly increased risk for PcP. While current heart transplantation guidelines recommend Pneumocystis jirovecii prophylaxis for up to 6-12 months after transplantation, after that period they only suggest an extended prophylaxis regimen in high-risk patients. Recent studies have identified several new risk factors that may be linked to an increased risk of PcP infection, including medication regimens and patient characteristics. Similarly, the indication for PcP prophylaxis in non-HIV patients has been expanded in relation to the introduction of new medications and therapeutic regimens for immune-mediated diseases. In our experience, the first patient was successfully treated with non-invasive ventilation, while the second required tracheal intubation, invasive ventilation, and extracorporeal CO2 removal due to severe respiratory failure. The aim of this double case report is to review the current timing of PcP prophylaxis after HT, the specific potential risk factors for PcP after HT, and the determinants of a prompt diagnosis and therapeutic approach in critically ill patients. We will also present a possible proposal for future investigations on indications for long-term prophylaxis.

Endemic Systemic Mycoses in Italy: A Systematic Review of Literature and a Practical Update

Endemic systemic mycoses such as blastomycosis, coccidioidomycosis, histoplasmosis, talaromycosis, paracoccidioidomycosis are emerging as an important cause of morbidity and mortality worldwide. We conducted a systematic review on endemic systemic mycoses reported in Italy from 1914 to nowadays. We found out: 105 cases of histoplasmosis, 15 of paracoccidioidomycosis, 10 of coccidioidomycosis, 10 of blastomycosis and 3 of talaromycosis. Most cases have been reported in returning travelers and expatriates or immigrants. Thirtytwo patients did not have a story of traveling to an endemic area. Fortysix subjects had HIV/AIDS. Immunosuppression was the major risk factor for getting these infections and for severe outcomes. We provided an overview on microbiological characteristics and clinical management principles of systemic endemic mycoses with a focus on the cases reported in Italy.

Blastomyces dermatitidis Septic Arthritis in a Renal Transplant Patient

Blastomycosis is a rare endemic fungal infection caused by the dimorphic fungus Blastomyces dermatitidis. It is more likely to occur in persons living in areas of the United States and Canada, which border the Ohio and Mississippi River Valleys and the Great Lakes region. Most infections are localized to the lungs, often presenting as acute or chronic pneumonia. Occasionally, patients progress to develop disseminated disease and extrapulmonary infections. Blastomycosis tends to be misdiagnosed initially at clinical evaluation as it is rare and may resemble other common conditions. We present a case of a 78-year-old immunosuppressed renal transplant patient who was suspected of having gout but eventually was diagnosed with an unusual presentation of septic arthritis of the ankle secondary to blastomycosis.

Updates on Histoplasmosis in Solid Organ Transplantation

Purpose of Review

Recent Findings

Summary

Fungal Infections in Liver Transplant Recipients

Invasive fungal infections (IFIs) are one of the most feared complications associated with liver transplantation, with high rates of morbidity and mortality. We discuss the most common invasive fungal infections in the setting of liver transplant, including Candida, Aspergillus, and Cryptococcal infections, and some less frequent but devastating mold infections. Further, we evaluate the use of prophylaxis to prevent invasive fungal infection in this population as a promising mechanism to reduce risks to patients after liver transplant.

Disseminated blastomycosis in a kidney transplant recipient

Disseminated blastomycosis in solid organ transplant is uncommon. The diagnosis is usually challenging due to vague clinical presentations, which could lead to a devastating outcome. We reported a unique case of disseminated blastomycosis with laryngeal involvement in a kidney transplant recipient who presented with hoarseness. The diagnosis was made by histopathology and culture of laryngeal mass.

Histoplasma capsulatum presenting as generalized lymphadenopathy after renal transplantation

Histoplasma capsulatum is typically an indolent disease among immunocompetent patients. However, immunocompromised patients, such as solid organ transplant recipients, are at risk of developing severe histoplasmosis. Yet post-transplant histoplasmosis is a rare pathology, representing less than five percent of invasive fungal infections among transplant recipients. Furthermore, patients tend to present with nonspecific clinical symptoms, complicating timely diagnosis and delaying treatment. Disease features that may be more representative of H. capsulatum infection, such as anemia, leukopenia and pulmonary involvement are often not present until late in the disease course, when the patient is at greater risk of decompensation. Unlike H. capsulatum infections among immunocompetent hosts, extrapulmonary infection among immunocompromised hosts is more the rule than the exception. Treatment with liposomal amphotericin B followed by oral itraconazole is the standard therapy, but special considerations must be made for patients with hepatic and/or renal insufficiency, underlying cardiac abnormalities or malabsorptive pathologies and doses of immunosuppressants will need to be adjusted for drug interactions. Herein we present a case of H. capsulatum infection presenting with generalized lymphadenopathy post-renal transplant.

Endemic fungal infections in solid organ transplant recipients-Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These updated guidelines from the Infectious Diseases Community of Practice of the American Society of Transplantation review the diagnosis, prevention and management of blastomycosis, histoplasmosis, and coccidioidomycosis in the pre- and post-transplant period. Though each of these endemic fungal infections has unique epidemiology and clinical manifestations, they all share a predilection for primary pulmonary infection and may cause disseminated infection, particularly in immunocompromised hosts. Culture remains the gold standard for definitive diagnosis, but more rapid diagnosis may be achieved with direct visualization of organisms from clinical specimens and antigen-based enzyme immunoassay assays. Serology is of limited utility in transplant recipients. The mainstay of treatment for severe infections remains liposomal amphotericin followed by a step-down azole therapy. Cases of mild to moderate severity with no CNS involvement may be treated with azole therapy alone. The newer generation azoles provide additional treatment options, but supported currently with limited clinical efficacy data. Azole therapy in transplant recipients presents a unique challenge owing to the drug-drug interactions with immunosuppressant agents. Therapeutic drug monitoring of azole levels is an essential component of effective and safe therapy. Infection prevention centers around minimizing epidemiological exposures, early clinical recognition, and azole prophylaxis in selected individuals.

Endemic Mycoses in Solid Organ Transplant Recipients

The endemic mycoses are a group of thermally dimorphic fungal pathogens occupying a specific geographic range. In North America, the chief endemic mycoses are histoplasmosis, coccidioidomycosis, and blastomycosis. Endemic fungi can cause serious infections in solid organ transplant recipients from primary infection, reactivation of latent disease, or donor-derived infection.

Pulmonary Histoplasmosis Identified by Video-Assisted Thoracic Surgery (VATS) Biopsy: a Case Report

Histoplasmosis is a common endemic mycosis in North, Central, and South America, but Korea is not known as an endemic area. We treated an immunocompetent Korean patient who had histoplasmosis. A 65-year-old Korean man presented with multiple pulmonary clumps of tiny nodules in the both lungs. He had been diagnosed 40 years earlier with pulmonary tuberculosis (TB) and a fungus ball had been diagnosed 4 years earlier. He denied any history of overseas travel. The patient visited our hospital with dyspnea, blood-tinged sputum, and weight loss, which had appeared 2 months earlier. The patient underwent video-assisted thoracic surgery (VATS) lung biopsy. The biopsy sample showed necrotizing granuloma and the presence of multiple small yeast-like fungi. Tissue culture confirmed Histoplasma capsulatum, and he was finally diagnosed with pulmonary histoplasmosis. Therapy was initiated with 200 mg itraconazole orally once per day. The symptoms disappeared 1 week after the start of treatment. After 4 months, low-dose chest computed tomography showed improvement in the ground glass opacity and size of the lung lesions. In conclusion, we report a case of an immunocompetent patient who developed histoplasmosis in Korea. When a patient shows unexplainable progressive infiltrative lung lesions, histoplasmosis should be considered as one of differential diagnoses although Korea is not an endemic area.

Standardization and validation of real time PCR assays for the diagnosis of histoplasmosis using three molecular targets in an animal model

Histoplasmosis is considered one of the most important endemic and systemic mycoses worldwide. Until now few molecular techniques have been developed for its diagnosis. The aim of this study was to develop and evaluate three real time PCR (qPCR) protocols for different protein-coding genes (100-kDa, H and M antigens) using an animal model. Fresh and formalin-fixed and paraffin-embedded (FFPE) lung tissues from BALB/c mice inoculated i.n. with 2.5x10⁶Histoplasma capsulatum yeast or PBS were obtained at 1, 2, 3, 4, 8, 12 and 16 weeks post-infection. A collection of DNA from cultures representing different clades of H. capsulatum (30 strains) and other medically relevant pathogens (36 strains of related fungi and Mycobacterium tuberculosis) were used to analyze sensitivity and specificity. Analytical sensitivity and specificity were 100% when DNAs from the different strains were tested. The highest fungal burden occurred at first week post-infection and complete fungal clearance was observed after the third week; similar results were obtained when the presence of H. capsulatum yeast cells was demonstrated in histopathological analysis. In the first week post-infection, all fresh and FFPE lung tissues from H. capsulatum-infected animals were positive for the qPCR protocols tested except for the M antigen protocol, which gave variable results when fresh lung tissue samples were analyzed. In the second week, all qPCR protocols showed variable results for both fresh and FFPE tissues. Samples from the infected mice at the remaining times post-infection and uninfected mice (controls) were negative for all protocols. Good agreement was observed between CFUs, histopathological analysis and qPCR results for the 100-kDa and H antigen protocols. We successfully standardized and validated three qPCR assays for detecting H. capsulatum DNA in fresh and FFPE tissues, and conclude that the 100-kDa and H antigen molecular assays are promising tests for diagnosing this mycosis.