Perspectives on Scedosporium species and Lomentospora prolificans in lung transplantation: Results of an international practice survey from ESCMID fungal infection study group and study group for infections in compromised hosts, and European Confederation of Medical Mycology

Metagenomics Applied to the Respiratory Mycobiome in Cystic Fibrosis

Cystic fibrosis (CF) is a genetic disorder characterized by chronic microbial colonization and inflammation of the respiratory tract (RT), leading to pulmonary exacerbation (PEx) and lung damage. Although the lung bacterial microbiota has been extensively studied, the mycobiome remains understudied. However, its importance as a contributor to CF pathophysiology has been highlighted. The objective of this review is to provide an overview of the current state of knowledge regarding the mycobiome, as described through NGS-based studies, in patients with CF (pwCF).Several studies have demonstrated that the mycobiome in CF lungs is a dynamic entity, exhibiting a lower diversity and abundance than the bacterial microbiome. Nevertheless, the progression of lung damage is associated with a decrease in fungal and bacterial diversity. The core mycobiome of the RT in pwCFs is mainly composed of yeasts (Candida spp., Malassezia spp.) and molds with lower abundance. Some fungi (Aspergillus, Scedosporium/Pseudallescheria) have been demonstrated to play a role in PEx, while the involvement of others (Candida, Pneumocystis) remains uncertain. The "climax attack" ecological model has been proposed to explain the complexity and interplay of microbial populations in the RT, leading to PEx and lung damage. NGS-based studies also enable the detection of intra- and interkingdom correlations between fungi and bacteria. Further studies are required to ascertain the biological and pathophysiological relevance of these correlations. Finally, with the recent advent of CFTR modulators, our understanding of the pulmonary microbiome and mycobiome in pwCFs is about to change.

Scedosporiosis and lomentosporiosis: modern perspectives on these difficult-to-treat rare mold infections

SUMMARYAlthough Scedosporium species and Lomentospora prolificans are uncommon causes of invasive fungal diseases (IFDs), these infections are associated with high mortality and are costly to treat with a limited armamentarium of antifungal drugs. In light of recent advances, including in the area of new antifungals, the present review provides a timely and updated overview of these IFDs, with a focus on the taxonomy, clinical epidemiology, pathogenesis and host immune response, disease manifestations, diagnosis, antifungal susceptibility, and treatment. An expansion of hosts at risk for these difficult-to-treat infections has emerged over the last two decades given the increased use of, and broader population treated with, immunomodulatory and targeted molecular agents as well as wider adoption of antifungal prophylaxis. Clinical presentations differ not only between genera but also across the different Scedosporium species. L. prolificans is intrinsically resistant to most currently available antifungal agents, and the prognosis of immunocompromised patients with lomentosporiosis is poor. Development of, and improved access to, diagnostic modalities for early detection of these rare mold infections is paramount for timely targeted antifungal therapy and surgery if indicated. New antifungal agents (e.g., olorofim, fosmanogepix) with novel mechanisms of action and less cross-resistance to existing classes, availability of formulations for oral administration, and fewer drug-drug interactions are now in late-stage clinical trials, and soon, could extend options to treat scedosporiosis/lomentosporiosis. Much work remains to increase our understanding of these infections, especially in the pediatric setting. Knowledge gaps for future research are highlighted in the review.

Lung infections due to emerging fungal pathogens

PURPOSE OF REVIEW

This review highlights the epidemiology, pathogenesis and clinical management of pulmonary infections caused by emerging fungal organisms.

RECENT FINDINGS

Emerging fungal infections have arisen as a result of population and environmental changes. An enlarging pool of immunocompromised hosts on triazole antifungal prophylaxis has led to an increased incidence of non- Aspergillus molds, such as Fusarium , Scedosporium and Lomentospora spp. Advances in diagnostic capabilities led to the identification of the Emergomyces genus and non- dermatitidis Blastomyces species, which have a significant disease burden in Africa and the Middle East. Climate change has contributed to changing the distribution of previously confined endemic mycoses, like coccidioidomycosis and talaromycosis. These emerging organisms pose important diagnostic and therapeutic challenges.

SUMMARY

Newly recognized pathogenic fungi and established endemic mycoses with expanding geographic boundaries have become important agents of pulmonary disease. There is a dearth of clinical evidence on the appropriate management of these infections.

Detection of Scedosporium spp.: Colonizer or pathogen? A retrospective analysis of clinical significance and management in a large tertiary center

Infections with Scedosporium spp. are emerging in the past two decades and are associated with a high mortality rate. Microbiological detection can be associated with either colonization or infection. Evolution from colonization into infection is difficult to predict and clinical management upon microbiological detection is complex. Microbiological samples from 2015 to 2021 were retrospectively analyzed in a single tertiary care center. Classification into colonization or infection was performed upon first microbiological detection. Clinical evolution was observed until July 2023. Further diagnostic procedures after initial detection were analyzed. Among 38 patients with microbiological detection of Scedosporium spp., 10 were diagnosed with an infection at the initial detection and two progressed from colonization to infection during the observation time. The main sites of infection were lung (5/12; 41.6%) followed by ocular sites (4/12; 33.3%). Imaging, bronchoscopy or biopsies upon detection were performed in a minority of patients. Overall mortality rate was similar in both groups initially classified as colonization or infection [30.7% and 33.3%, respectively (P = 1.0)]. In all patients where surgical debridement of site of infection was performed (5/12; 42%); no death was observed. Although death occurred more often in the group without eradication (3/4; 75%) compared with the group with successful eradication (1/8; 12.5%), statistical significance could not be reached (P = 0.053). As therapeutic management directly impacts patients' outcome, a multidisciplinary approach upon microbiological detection of Scedosporium spp. should be encouraged. Data from larger cohorts are warranted in order to analyze contributing factors favoring the evolution from colonization into infection.

Lomentospora prolificans: An Emerging Opportunistic Fungal Pathogen

Lomentospora prolificans is an emerging opportunistic pathogen that primarily affects immunocompromised individuals leading to disseminated disease with high mortality rates while also causing infections in healthy populations. Successful recovery from infection is difficult due to high rates of intrinsic resistance to antifungals. Rapid and readily available diagnostic methods, aggressive surgical debridement wherever appropriate, and effective and timely antifungal treatment are the pillars for successful management. Future research will need to clarify the environmental niche of the fungus, further investigate the pathophysiology of infection and define species-specific therapeutic targets.

Fungal Infections in Lung Transplantation

Purpose of Review

We aim to understand the most common fungal infections associated with the post-lung transplant period, how to diagnose, treat, and prevent them based on the current guidelines published and our center’s experience.

Recent Findings

Different fungi inhabit specific locations. Diagnosis of invasive fungal infections (IFIs) depends on symptoms, radiologic changes, and a positive microbiological or pathology data. There are several molecular tests that have been used for diagnosis. Exposure to fungal prophylaxis can predispose lung transplant recipients to these emerging molds. Understanding and managing medication interactions and drug monitoring are essential in successfully treating IFIs.

Summary

With the increasing rate of lung transplantations being performed, and the challenges posed by the immunosuppressive regimen, understanding the risk and managing the treatment of fungal infections are imperative to the success of a lung transplant recipient. There are many ongoing clinical trials being conducted in hopes of developing novel antifungals.

Multiresistant organisms: bacteria and beyond

PURPOSE OF REVIEW

Infections with multiresistant organisms are an emerging problem, cause early mortality post lung transplantation and are sometimes associated with graft dysfunction. Frequently they raise questions about the selection of lung transplant candidates and therapeutic management post lung transplantation. There are no guidelines and management must be individualized. This review summarizes the available therapeutic options in cases of multidrug-resistant (MDR) organisms and outcomes after lung transplant.

RECENT FINDINGS

Improvements in diagnosis, new and more effective drugs and the experience gained in the management of these infections in lung transplantation, lead to a more optimistic horizon than that found a decade ago.

SUMMARY

Update on the management of Burkholderia cepacia complex, Mycobacterium abscessus complex, Aspergillus spp., Scedosporium spp. and Lomentospora prolificans infections. This review clarifies current posttransplant outcomes and adds a little hope in these scenarios.

Scedosporium and Lomentospora Infections Are Infrequent, Difficult to Diagnose by Histology, and Highly Virulent

OBJECTIVE

To further characterize the histomorphology and clinicopathologic features of colonization and invasive disease by Scedosporium and Lomentospora.

METHODS

We conducted a 20-year retrospective study. Patients with at least 1 histopathology specimen and concurrent culture were included. Clinical features, histopathology, microbiology, and outcomes were analyzed.

RESULTS

Eighteen patients were identified, and all were immunocompromised. Eight patients had colonization, while 10 had invasive disease (pneumonia [n = 3], skin and soft-tissue infections [n = 3], disseminated disease [n = 4]). Scedosporium apiospermum was identified in 15 patients, Lomentospora prolificans in 2 patients, and Scedosporium ellipsoideum in 1 patient. Fungal elements were identified histologically in 11 patients. Granulomatous, suppurative, and necrotizing inflammation with irregular branching hyphae and characteristic microconidia were observed in 9 cases; conidiogenous cells were identified in 4 cases. Seven patients died of invasive disease despite therapy, and 3 recovered after treatment. No deaths were observed in patients with colonization.

CONCLUSIONS

Scedosporium and Lomentospora are rare, virulent opportunistic fungal pathogens. Fungal morphology may overlap with other hyaline molds, but identification of obovoid conidia should allow a diagnosis of non-Aspergillus hyalohyphomycosis and consideration of Scedosporium and Lomentospora. Histopathologic correlation with culture and polymerase chain reaction is critical for diagnosis and treatment.

Biochemical and structural studies of target lectin SapL1 from the emerging opportunistic microfungus Scedosporium apiospermum

Scedosporium apiospermum is an emerging opportunistic fungal pathogen responsible for life-threatening infections in humans. Host-pathogen interactions often implicate lectins that have become therapeutic targets for the development of carbohydrate mimics for antiadhesive therapy. Here, we present the first report on the identification and characterization of a lectin from S. apiospermum named SapL1. SapL1 was found using bioinformatics as a homolog to the conidial surface lectin FleA from Aspergillus fumigatus known to play a role in the adhesion to host glycoconjugates present in human lung epithelium. In our strategy to obtain recombinant SapL1, we discovered the importance of osmolytes to achieve its expression in soluble form in bacteria. Analysis of glycan arrays indicates specificity for fucosylated oligosaccharides as expected. Submicromolar affinity was measured for fucose using isothermal titration calorimetry. We solved SapL1 crystal structure in complex with α-methyl-L-fucoside and analyzed its structural basis for fucose binding. We finally demonstrated that SapL1 binds to bronchial epithelial cells in a fucose-dependent manner. The information gathered here will contribute to the design and development of glycodrugs targeting SapL1.

Lung transplantation: candidate selection and timing of transplant

PURPOSE OF REVIEW

Over the past two decades, lung transplant has become the mainstay of treatment for several end-stage lung diseases. As the field continues to evolve, the criteria for referral and listing have also changed. The last update to these guidelines was in 2014 and several studies since then have changed how patients are transplanted. Our article aims to briefly discuss these updates in lung transplantation.

RECENT FINDINGS

This article discusses the importance of early referral of patients for lung transplantation and the concept of the 'transplant window'. We review the referral and listing criteria for some common pulmonary diseases and also cite the updated literature surrounding the absolute and relative contraindications keeping in mind that they are a constantly moving target. Frailty and psychosocial barriers are difficult to assess with the current assessment tools but continue to impact posttransplant outcomes. Finally, we discuss the limited data on transplantation in acute respiratory distress syndrome (ARDS) due to COVID19 as well as extracorporeal membrane oxygenation bridge to transplantation.

SUMMARY

The findings discussed in this article will strongly impact, if not already, how we select candidates for lung transplantation. It also addresses some aspects of lung transplant such as frailty and ARDS, which need better assessment tools and clinical data.

Pneumonia With Scedosporium apiospermum and Lomentospora prolificans in a Patient After Bilateral Lung Transplantation for Pulmonary Hypertension: A Case Report

Infections caused by the Scedosporium genus have become recognized as a fatal complication after lung transplantation in Europe and Australia, but the reports have been rare from Asian countries including Japan. We present a case of pneumonia caused by a mixed infection of Scedosporium apiospermum (SA) and Lomentospora prolificans (LP) that developed after augmentation of immunosuppression for chronic lung allograft dysfunction (CLAD) after lung transplantation. A 13-year-old man underwent bilateral lung transplantation for pulmonary hypertension. One year after surgery, he was treated with a series of augmented immunosuppressive therapy for severe acute rejection and subsequent CLAD. Three months following the first steroid pulse therapy, his serum β-D-glucan elevated without any sign of fungal infection by other tests. The serum β-D-glucan once returned to a normal level by empirical administration of micafungin; however, the patient's condition worsened again by discontinuation of it. He did not recover by restarting micafungin, and computed tomography (CT) scans eventually demonstrated new infiltrates in his lung field 6 weeks after the elevation of serum β-D-glucan. Microscopic findings of transbronchial lung biopsy specimens showed filamentous fungi, and the culture of bronchoalveolar lavage fluid revealed the growth of SA and LP. Despite subsequent voriconazole administration, he died 14 days after the start of voriconazole. Early and aggressive inspection including bronchoscopy should be performed for the diagnosis of Scedosporium infection in immunocompromised patients, even if CT scans and sputum culture show no evidence of infection.

Scedosporium apiospermum and Lomentospora prolificans in lung transplant patients - A single center experience over 24 years

INTRODUCTION

Scedosporium apiospermum and Lomentospora prolificans (Scedosporium/Lomentospora) species are emerging, multi-resistant pathogens that cause life-threatening illnesses among lung transplant (LTx) recipients. The current epidemiology and management in LTx are unknown.

METHODS

We performed a retrospective single center audit of all sputum/bronchoscopy samples for Scedosporium/Lomentospora species in LTx patients over a 24-year period (1995-2019). Patients were diagnosed as colonized or with invasive fungal disease.

RESULTS

From a cohort of 962 LTx recipients, 30 patients (3.1%) cultured Scedosporium/Lomentospora (1.2%, 1.9%, respectively). There were no isolates from 1995 to 2013, with multiple yearly isolates thereafter. Nineteen (63%) cases were classified as IFD, and 11 (37%) as colonization. The median time to first culture from transplantation was 929 days (Interquartile-range [IQR] 263-2960). Most patients (63%) had received antifungals prior to the first positive culture of Scedosporium/Lomentospora for other fungal infection. The most common antifungal used for treatment of Scedosporium/Lomentospora was posaconazole (n = 16; 53%). Median duration of therapy was 364 days (IQR 164-616). Treatment was associated with improved lung function over 6 months (median FEV1 increased from 1.3L[IQR 0.9-1.8L] to 1.8L[IQR 1.1-2.3] P = .05). Six patients cultured Scedosporium/Lomentospora prior to transplantation, and no survival disadvantage was seen as compared to our whole LTx cohort (P = .8).

CONCLUSION

Our single center 24-year experience suggests that the incidence of Scedosporium/Lomentospora is increasing. Scedosporium/Lomentospora is typically isolated several years after LTx, and requires prolonged anti-fungal treatment that is usually associated with improved in lung function. Culture of Scedosporium/Lomentospora prior to LTx did not pose a survival disadvantage. Further surveillance is required to fully characterize implications of these organisms for LTx recipients.

Update on Respiratory Fungal Infections in Cystic Fibrosis Lung Disease and after Lung Transplantation

Cystic fibrosis is the most common autosomal-recessive metabolic disease in the Western world. Impaired trans-membrane chloride transport via the cystic fibrosis transmembrane conductance regulator (CFTR) protein causes thickened body fluids. In the respiratory system, this leads to chronic suppurative cough and recurrent pulmonary infective exacerbations, resulting in progressive lung damage and respiratory failure. Whilst the impact of bacterial infections on CF lung disease has long been recognized, our understanding of pulmonary mycosis is less clear. The range and detection rates of fungal taxa isolated from CF airway samples are expanding, however, in the absence of consensus criteria and univocal treatment protocols for most respiratory fungal conditions, interpretation of laboratory reports and the decision to treat remain challenging. In this review, we give an overview on fungal airway infections in CF and CF-lung transplant recipients and focus on the most common fungal taxa detected in CF, Aspergillus fumigatus, Candida spp., Scedosporium apiospermum complex, Lomentospora species, and Exophiala dermatitidis, their clinical presentations, common treatments and prophylactic strategies, and clinical challenges from a physician’s point of view.

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.

Clinical Usefulness of Susceptibility Breakpoints for Yeasts in the Treatment of Candidemia: A Noninterventional Study

This prospective noninterventional study evaluated whether antifungal susceptibility data (MIC) provided for Candida clinical isolates on the basis of recently established breakpoints are taken into account by clinicians to guide their treatment decision making process, and assessed the response in MIC- and non-MIC-based treatment groups. During a six month period, the usage of systemic antifungals was recorded in detail and compared with mycological data (Candida species and MICs) in candidemia patients. Patients were assigned to a susceptible or resistant infection group based on European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints; treatment decisions were under the professional discretion of the treating physicians. 123 patients were evaluated with Candida albicans accounting for 59%, Candida glabrata for 19%, Candida parapsilosis for 15%, Candida tropicalis for 4% and Candida krusei for 3%. Antifungal treatment correlated with species and MICs in 80% (n = 99 patients), high MICs and species-dependent guideline recommendations were ignored in 20% (n = 24 patients); the overall outcome of candidemia cases in our study population was excellent, as by day 14, all patients were cleared from fungal blood stream infection (mean 5.6 days, range 2–12). The current variability in antifungal usage and the delay in initiating appropriate therapy indicate a need for antifungal stewardship to improve the management of invasive fungal infections.

Clinical characteristics and outcomes of invasive Lomentospora prolificans infections: Analysis of patients in the FungiScope® registry

OBJECTIVES

Invasive fungal infections caused by Lomentospora prolificans are associated with very high mortality rates and can be challenging to treat given pan-drug resistance to available antifungal agents. The objective of this study was to describe the clinical presentation and outcomes in a cohort of patients with invasive L prolificans infections.

METHODS

We performed a retrospective review of medical records of patients with invasive L prolificans infection in the FungiScope^® registry of rare invasive fungal infections. Patients diagnosed between 01 January 2008 and 09 September 2019 were included in for analysis.

RESULTS

The analysis included 41 patients with invasive L prolificans infection from eight different countries. Haematological/oncological malignancies were the most frequent underlying disease (66%), disseminated infection was frequent (61%), and the lung was the most commonly involved organ (44%). Most infections (59%) were breakthrough infections. Progression/deterioration/treatment failure was observed in 23/40 (58%) of patients receiving antifungal therapy. In total, 21/41 (51%) patients, and 77% of patients with underlying haematological/oncological malignancy, had a fatal outcome attributed to invasive fungal infection. Combination antifungal therapy was frequent (24/40) and associated with improved survival. In particular, treatment regimens including terbinafine were significantly associated with higher treatment success at final assessment (P = .012), with a positive trend observed for treatment regimens that included voriconazole (P = .054).

CONCLUSIONS

Lomentospora prolificans infections were associated with mortality rates of 77% and above in patients with underlying haematological/oncological malignancies and those with disseminated infections. While combination therapy is the preferred option for now, the hope lies with novel antifungals currently under development.