The epidemiology of invasive fungal infections in transplant recipients

Transplant patients, including solid-organ transplant (SOT) and hematopoietic stem cell transplant (HSCT) recipients, are exposed to various types of complications, particularly rejection. To prevent these outcomes, transplant recipients commonly receive long-term immunosuppressive regimens that in turn make them more susceptible to a wide array of infectious diseases, notably those caused by opportunistic pathogens. Among these, invasive fungal infections (IFIs) remain a major cause of mortality and morbidity in both SOT and HSCT recipients. Despite the continuing improvement in early diagnostics and treatments of IFIs, the management of these infections in transplant patients is still complicated. Here, we provide an overview concerning the most recent trends in the epidemiology of IFIs in SOT and HSCT recipients by describing the prominent yeast and mold species involved, the timing of post-transplant IFIs and the risk factors associated with their occurrence in these particularly weak populations. We also give special emphasis into basic research advances in the field that recently suggested a role of the global and long-term prophylactic regimen in orchestrating various biological disturbances in the organism and conditioning the emergence of the most adapted fungal strains to the particular physiological profiles of transplant patients.

Unusual presentation of disseminated cryptococcal infection complicated by myocarditis in a heart transplant recipient

BACKGROUND

Cryptococcus neoformans is the third most common cause of invasive fungal infection in solid organ transplant (SOT) recipients. While cryptococcal infection can involve any organ, cases of myocarditis are exceedingly rare.

METHODS

A retrospective chart review was completed for this case report.

RESULTS

We present the case of a 21-year-old heart transplant recipient who developed disseminated cryptococcal infection with biopsy-proven cryptococcal myocarditis.

CONCLUSIONS

Cryptococcal disease in SOT recipients poses diagnostic and therapeutic challenges. There are no current guidelines for the duration of cryptococcal myocarditis treatment. Repeat myocardial biopsy may play a role in guiding length of therapy.

Cryptococcal Meningoencephalitis in Phenotypically Normal Patients

Cryptococcosis is an invasive fungal infection found worldwide that causes significant morbidity and mortality among a broad range of hosts. There are approximately 223,000 new cases of cryptococcosis annually throughout the world, and at least 180,000 deaths are attributed to this infection each year. Most of these are due to complications of cryptococcal meningoencephalitis among HIV-infected patients in resource-limited environments. The majority of individuals diagnosed with cryptococcosis have underlying conditions associated with immune dysfunction such as HIV, solid organ transplant, hematologic malignancy, organ failure syndromes, and/or the use of immunosuppressive agents such as glucocorticosteroids and biologic agents. In most clinical series, there is a small proportion of patients with cryptococcosis who are phenotypically normal; that is, they have no clinically obvious predisposition to disease. Cryptococcal meningoencephalitis (CME) presentation and management differ substantially between these normal individuals and their immunocompromised counterparts. In this review, we will focus on CME in the phenotypically normal host and underscore differences in the clinical presentation, management, outcome, and potential risk factors for these patients compared to immunocompromised persons who develop this potential devastating invasive fungal infection.

Comparison of different therapeutic approaches for pulmonary cryptococcosis in kidney transplant recipients: a 15-year retrospective analysis

Introduction

Organ transplant recipients are at increased risk of developing pulmonary cryptococcosis (PC) due to weakened cell-mediated immunity caused by immunosuppressors. However, the nonspecific symptoms associated with PC can often lead to misdiagnosis and inappropriate treatment.

Methods

We conducted a retrospective analysis of data from 23 kidney transplant recipients with PC between April 2006 to January 2021.

Results

The median time from transplantation to the diagnosis of pathology-proven PC 4.09  years. Seventeen patients presented respiratory symptoms, including sputum-producing cough and dyspnea. Additionally, three patients also developed central nervous system (CNS) infections. Chest CT scans frequently revealed nodule-shaped lesions, which can mimic lung carcinoma. Serological tests did not demonstrate any specific changes. Nine patients received surgical resection as treatment. Fourteen patients were treated with antifungal medication only. No recurrence was observed in all 23 patients.

Conclusion

Our study suggests that fever and sputum-producing cough are common symptoms of PC, and cryptococcal meningitis should not be excluded if corresponding symptoms occur. Fluconazole is a common and effective antifungal agent. Surgical resection should be considered for patients who do not respond well to antifungal therapy. Clinicians should be aware of these findings when evaluating transplant recipients with respiratory symptoms.

Minimizing the Risk of Donor-Derived Events and Maximizing Organ Utilization Through Education and Policy Development

Herein, we review the current knowledge of donor-derived disease and current US Organ Procurement and Transplantation Network policies to minimize the risk. During the process, we also consider actions to further mitigate the risk of donor-derived disease. The overarching goal is to provide an infectious disease perspective on the complex decision of organ acceptance for transplant programs and candidates.

Cluster of Donor-Derived Cryptococcosis after Liver and Kidney Transplantation

Cryptococcosis infection after transplantation is easily overlooked or misdiagnosed. We report a cluster of donor-derived cryptococcosis infection in liver and kidney transplant recipients from the same donor in China. Infections occurred within 1 month after transplantation, and were confirmed by using biopsies and blood tests.

Donor-derived Cryptococcus gattii sensu stricto infection in two kidney transplant recipients, southeastern United States

Cryptococcus gattii infection is a rare cause of severe pulmonary disease and meningoencephalitis that has only recently been detected in the southeastern United States. We describe an organ transplant-associated outbreak of C. gattii infection involving an HIV-negative immunosuppressed donor in this region who died following new-onset headache and seizure of unknown cause. Retrospective cryptococcal antigen (CrAg) testing of donor serum was positive. Two of the three transplant recipients developed severe C. gattii infection 11 and 12 weeks following transplantation. One recipient died from severe pulmonary infection, identified on autopsy, and the other ill recipient survived following treatment for cryptococcal meningitis. This outbreak underscores the importance of considering cryptococcosis in patients with clinical findings suggestive of subacute meningitis or other central nervous system (CNS) pathology, and the potential benefit of routine pre-transplant donor CrAg screening using lateral flow assay to guide recipient antifungal prophylaxis. The case also adds to emerging evidence that C. gattii is a potential threat in the southeastern United States.

Donor-Derived Transmission of Cryptococcus gattii sensu lato in Kidney Transplant Recipients

We describe cases of donor-derived transmission of Cryptococcus deuterogattii in 2 kidney transplant recipients in Brazil and published information on other cases. Prompt reduction of immunosuppression and initiation of antifungal therapy was required to successfully control the fungal infections and preserve engraftment.

Cryptococcosis

Cryptococcosis is an invasive fungal infection of global significance caused by yeasts of the genus Cryptococcus. The prevalence of HIV in certain areas of the world and the expanding population of immunocompromised patients contribute to the ongoing global disease burden. Point-of-care serologic testing has allowed for more rapid diagnosis and implementation of screening programs in resource-limited settings. Management involves therapy aimed at reduction in fungal burden, maintenance of intracranial pressure, and optimization of host immunity. Despite diagnostic and therapeutic advances, cryptococcosis continues to be a disease with unacceptably high incidence and mortality, particularly in resource-limited settings.

Cryptococcus transmission through solid organ transplantation in the United States: A report from the Ad Hoc Disease Transmission Advisory Committee

Cryptococcus species can cause serious life-threatening infection in solid organ transplant recipients by reactivation of prior infection, posttransplant de novo infection, or donor transmission from the transplanted organ. Although previously reported in the literature, the extent of donor-derived cryptococcosis in the United States has not been documented. We analyzed potential donor-derived Cryptococcus transmission events reported to the Organ Procurement and Transplantation Network (OPTN) for investigation by the Ad Hoc Disease Transmission Advisory Committee (DTAC). All reports between 2009 and 2019 in which transmission to recipients was designated proven or probable, or determined to be averted due to implementation of prophylaxis (intervention without disease transmission-"IWDT") were included. During 2009-2019, 58 reports of potential donor-derived cryptococcosis were submitted to DTAC. Among these reports, 12 donors were determined to have resulted in proven or probable transmission to 23/34 (67.6%) recipients. Most of these donors (10/12 [83%]) exhibited central nervous system-related symptoms prior to death and 5/23 (22%) infected recipients died. For 11 different donors, prophylaxis, most often with fluconazole, was administered to 23/35 (65.7%) recipients. Clinicians should maintain awareness of donor-derived cryptococcosis and consider prompt prophylaxis or treatment followed by reporting to OPTN for further investigation.

Understanding rare infections post-lung transplantation

Introduction: Lung transplant recipients are at the highest risk of infectious complications among all solid-organ transplant (SOT) recipients. In the current era, many standardized protocols in terms of diagnostic algorithms, prophylaxis, and therapeutic strategies have improved the management of the most common infectious complications. Conversely, diagnosis of rare infections can be particularly challenging and this can delay appropriate treatment.Areas covered: This article will review the epidemiology, clinical presentation, diagnostic and therapeutic management of certain rarely reported viral, fungal, bacterial and parasitic infections in lung transplant recipients.Expert opinion: Once the most frequent infections are excluded, clinical suspicion combined with molecular diagnostic methods such as targeted and broad-spectrum PCRs can allow diagnosis of a rare infection. A multidisciplinary team, including transplant pulmonologists, transplant infectious diseases specialists, microbiologists and pathologists is essential for prompt diagnosis and optimal therapeutic management.

Opportunistic Infections in Transplant Patients

Transplants have become common with excellent patient and graft outcomes owing to advances in surgical technique, immunosuppression, and antimicrobial prophylaxis. In 2017, 34,770 solid organ transplants were performed in the United States. For solid organ transplant recipients, infection remains a common complication owing to the regimens required to prevent rejection. Opportunistic infections, which are infections that are generally of lower virulence within a healthy host but cause more severe and frequent disease in immunosuppressed individuals, typically occur in the period 1 month to 1 year after transplantation. This article focuses on opportunistic infections in the solid organ transplant recipient.

Very early-onset of Cryptococcus neoformans disease following liver transplantation: Report of two cases and a review of the literature

Cryptococcosis is the third most common invasive fungal infection following solid organ transplantation, and mortality is high. Most cases occur late and are due to reactivation of latent infection; however, very early reactivation and donor-derived transmission can occur. Routine screening pre-transplant and antifungal prophylaxis for cryptococcosis post-transplant in solid organ transplantation are not standard practice. We present two cases of very early-onset Cryptococcus neoformans disease following liver transplantation to highlight the need to consider individualized pre-transplant screening and be aware that reactivation of Cryptococcosis neoformans can occur in the immediate post-transplant period.

Cryptococcosis in Patients following Kidney Transplantation: A 9-Year Retrospective Clinical Analysis at a Chinese Tertiary Hospital

Background

Cryptococcosis following kidney transplantation (KT) is rare but is associated with considerably increased risk of mortality. At present, data on the association between cryptococcosis and KT in mainland China remain relatively limited.

Objectives

This study aims to review our experience related to the management of cryptococcosis following KT at a Chinese tertiary hospital.

Methods

All patients with cryptococcosis following KT admitted to our hospital from January 2010 to December 2018 were reviewed.

Results

A total of 37 patients with cryptococcosis were enrolled (males: 62.2%). The mean age of the patients was 49.5 ± 9.38 (20-64) years. The average time to infection following KT was 7.0 ± 5.50 years (5 months to 21 years), and 30 patients (81.1%) had cryptococcosis onset >2 years following transplantation. The most common site of infection was the central nervous system, followed by the pulmonary system and skin. Most patients received fluconazole or voriconazole with or without flucytosine as their initial treatment regimen at our hospital. The 2-week mortality rate was 8.1% (3/37), and five patients (13.5%) died within 6 months of being diagnosed with cryptococcosis. Remarkably, all patients who received high-dose fluconazole (800 mg daily) or voriconazole ± flucytosine survived.

Conclusions

Cryptococcosis in kidney transplant recipients is typically a late-occurring infection, with most patients having cryptococcosis onset >2 years following KT at our hospital. The central nervous system, pulmonary system, and skin are the main sites of infection. Voriconazole or high-dose fluconazole can be used as an alternative therapy for post-KT cryptococcosis.

Pneumonia in solid organ transplantation: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These guidelines from the AST Infectious Diseases Community of Practice review the diagnosis and management of pneumonia in the post-transplant period. Clinical presentations and differential diagnosis for pneumonia in the solid organ transplant recipient are reviewed. A two-tier approach is proposed based on the net state of immunosuppression and the severity of presentation. With a lower risk of opportunistic, hospital-acquired, or exposure-specific pathogens and a non-severe presentation, empirical therapy may be initiated under close clinical observation. In all other patients, or those not responding to the initial therapy, a more aggressive diagnostic approach including sampling of tissue for microbiological and pathological testing is warranted. Given the broad range of potential pathogens, a microbiological diagnosis is often key for optimal care. Given the limited literature comparatively evaluating diagnostic approaches to pneumonia in the solid organ transplant recipient, much of the proposed diagnostic algorithm reflects clinical experience rather than evidence-based data. It should serve as a template which may be modified according to local needs. The same holds true for the suggested empiric therapies, which need to be adapted to the local resistance patterns. Further study is needed to comparatively evaluate diagnostic and empiric treatment strategies in SOT recipients.

Cryptococcosis in solid organ transplantation-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 cryptococcosis in the pre- and post-transplant period. The current update now includes a discussion of cryptococcosis, which is the third most common invasive fungal infection in SOT recipients. Infection often occurs a year after transplantation; however, early infections occur and donor-derived infections have been described within 3 months after transplant. There are two main species that cause infection, Cryptococcus neoformans and C gattii. Clinical onset may be insidious, but headaches, fevers, and mental status changes should warrant diagnostic testing. The lateral flow cryptococcal antigen assay is now the preferred test from serum and cerebrospinal fluid due to its rapidity, accuracy, and cost. A lumbar puncture with measurement of opening pressure is recommended for patients with suspected or proven cryptococcosis. Lipid amphotericin B plus 5-flucytosine is used as initial treatment of meningitis, disseminated infection, and moderate-to-severe pulmonary infection, followed by fluconazole as consolidation therapy. Fluconazole is effective for mild-to-moderate pulmonary infection. Immunosuppression reduction as part of management may lead to immune reconstitution syndrome that may resemble active disease.

Implementation of a Strongyloides screening strategy in solid organ transplant donors and recipients

BACKGROUND

Strongyloides stercoralis infects 100 million people worldwide. Mortality rates in hyperinfection syndrome exceed 50%. Donor-derived Strongyloides infection has occurred after heart, kidney, kidney-pancreas and liver transplantation; yet, only 10% of the US organ procurement organizations currently screen donors for strongyloidiasis.

METHODS

We report a fatal case of donor-derived disseminated Strongyloides infection in a liver transplant recipient. Following this case, we implemented universal screening and treatment of donors and recipients. We reviewed our local epidemiology and outcomes after protocol implementation.

RESULTS

From a total of 355 deceased donors accepted at our center between January 2016, and March 2018, 14 (3.9%) had positive Strongyloides serology. Except for the index case, all other recipients of Strongyloides antibody-positive donors within that period (including 10 kidneys, 3 livers, one combined liver/kidney, and one kidney/pancreas from eight seropositive donors) received post-transplant prophylaxis with ivermectin, and to date are alive and doing well without signs of infection. Between October 2015, and September 2016, a total of 441 deceased donor solid organ transplants were performed at our center. 220 of these recipients had pretransplant Strongyloides serology available, and 23 of them were seropositive (10.5%). Within the first two years after the implementation of universal screening and treatment of donors and recipients, we had no cases of Strongyloides reactivation in our center.

CONCLUSIONS

Implementation of a Strongyloides screening and treatment protocol in our center was an effective strategy to prevent both recipient- and donor-derived strongyloidiasis. Transplant centers should consider implementation of Strongyloides preventive strategies.

Solving the mystery: Hyalinized cyst wall containing organism-like structures in a lung transplant donor

A 59-year-old man with non-ischemic cardiomyopathy underwent orthotopic heart transplantation. The donor, a 31-year-old male declared brain dead after a gunshot wound to the head, was considered high risk due to history of incarceration, illicit drug use, and sex with a HIV-positive partner. At organ procurement, the heart, kidneys, pancreas, and liver looked grossly normal. A small right lower lobe nodule was noticed, and lung biopsy was performed. Bronchoscopy showed purulent secretions in the right lower lobe. Images from pathology are presented. Lung biopsy confirmed the presence of hyalinized cyst wall containing organism-like structures. A combination of culture, microscopic morphology, and gene sequencing was used to identify the causative organism. The patient and all other organ recipients received appropriate antifungal prophylaxis and remain asymptomatic 6 months post-transplant.