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

Clinical significance and antifungal susceptibility profile of 103 clinical isolates of Scedosporium species complex and Lomentospora prolificans obtained from NIH patients

Reduced susceptibility to antifungals is common among members of genera Scedosporium and Lomentospora, with optimal treatments still not fully defined. In vitro antifungal susceptibility results and clinical data do not comprehensively account for the advent of new Scedosporium species identified by molecular phylogenetics. Using Clinical and Laboratory Standards Institute (CLSI) methodology, we tested a total of 103 clinical isolates obtained from patients at the NIH Clinical Center. The most frequent species were Scedosporium apiospermum (63%) and Scedosporium boydii (11%), followed by Lomentospora prolificans (7%). The novel antifungal olorofim showed the lowest MICs against all Scedosporium spp. and L. prolificans, followed by micafungin. Among the triazoles, voriconazole showed lower MICs against Scedosporium spp. Amphotericin B and posaconazole demonstrated species-specific and inter-species variable activity. Itraconazole, isavuconazole, and terbinafine had higher MIC values against Scedosporium spp. and L. prolificans. Clinical data were retrospectively reviewed for 90 isolates, of which nine patients (28 isolates) had active disease/infection and received antifungal treatment that included voriconazole or posaconazole. Five of these patients (56%) died, while three patients (33%) with chronic granulomatous disease were cured following hematopoietic cell transplantation. In 24 patients (62 isolates), the presence of the fungus was considered airway colonization. In conclusion, our data support the existence of species-specific and inter-species differences in the antifungal susceptibility patterns among members of genera Scedosporium and L. prolificans. The novel investigational antifungal olorofim may be a promising therapy. Our clinical data suggest that host status and administration of antifungal therapy most effective for each Scedosporium species complex are important determinants of outcomes.IMPORTANCEUnderstanding the epidemiology and clinical spectrum of infections caused by Scedosporium species complex and Lomentospora prolificans is integral to improving outcomes, particularly in severely ill and immunocompromised patients. In vitro antifungal susceptibility testing can provide an estimate of antifungal activity against fungal pathogens. Our study showed that species-specific and inter-species differences exist in the distribution of antifungal susceptibility patterns between Scedosporium and L. prolificans. Our clinical data also highlight that host status, along with effective antifungal therapy, plays a crucial role in determining treatment outcomes.

Clinical Significance and Therapeutic Challenges of Scedosporium spp. and Lomentospora prolificans Isolates in a Single-Center Cohort of Lung Transplant Recipients

(1) Background: Emerging fungal infections associated with Scedosporium spp. and Lomentospora prolificans (S/L) are becoming more frequent and are very difficult to treat. Our objective was to analyze the frequency and management of S/L isolates in lung transplant (LTx) recipients, the patient outcomes and in vitro antifungal sensitivity. (2) Methods: We included all patients with S/L isolation during post-transplant follow-up. Data were collected from electronic medical records. All samples were cultivated on Sabouraud Chloramphenicol agar. Isolations of S/L were submitted to in vitro susceptibility tests. (3) Results: A total of 11 (2%) of the 576 LTx recipients included had at least one isolation of S/L. Classification for the 11 cases were colonization (4; 36%) and infection (7; 65%). Five infections were pulmonary (71%) and two were disseminated (29%). S. apiospermum complex was the most frequently occurring isolation in patients with pulmonary disease while L. prolificans was the most frequent in patients with disseminated disease. Ten patients were treated. The most frequent antifungal drugs used were voriconazole (n = 8) and terbinafine (n = 6). Seven patients (70%) received more than one drug. The mortality rate associated with L. prolificans isolation was 50% for colonization and 100% for disseminated disease. (4) Conclusions: Scedosporium spp. and L. prolificans infections are associated with high morbidity and mortality rates. New diagnostic and therapeutic tools are required to reduce the impact of these infections.

Diagnosing invasive fungal infections in the laboratory today: It's all good news?

Despite the advances in medical science, invasive fungal infections (IFI) remain a diagnostic challenge. The increasing prevalence of IFI, driven by immunosuppressive therapies, advances in intensive care and emerging pathogens, underscores the need for early and accurate diagnosis. This review evaluates current laboratory methods for the diagnosis of IFI, highlighting their strengths and limitations. Conventional techniques, including fungal culture, direct microscopy, and histopathology, remain the gold standard for the diagnosis of proven IFIs. These methods allow pathogen isolation, species identification and antifungal susceptibility testing. However, these techniques have limitations in terms of sensitivity and turnaround times. Although microscopy is a rapid technique, its sensitivity and species discrimination profile are limited. Modern serological assays, such as β-d-glucan and galactomannan detection, have improved the diagnostic accuracy of probable IFI cases. Integration of these assays with clinical and radiological findings, enables earlier intervention, although this is accompanied by an increased risk of false positives and necessitates careful clinical correlation. Molecular diagnostics, particularly polymerase chain reaction (PCR), allow rapid, species-specific identification directly from clinical samples. The advent of MALDI-TOF mass spectrometry has further improved diagnostic efficiency, particularly for yeast identification, although challenges remain for filamentous fungi. Innovative techniques, such as metagenomic sequencing, lateral-flow assays, and loop-mediated isothermal amplification, offer the potential for rapid and precise detection, even in resource-limited settings. The combination of conventional and innovative methods provides a comprehensive diagnostic framework. The continuous refinement of these tools, in conjunction with multidisciplinary collaboration, is imperative to improve the early diagnostic and targeted treatment of patients with IFI.

New and emerging roles for inhalational and direct antifungal drug delivery approaches for treatment of invasive fungal infections

INTRODUCTION

The rising prevalence of difficult-to-treat, deep-seated invasive fungal diseases (IFD) has led to high mortality. Currently available antifungal treatments, administered predominantly orally or intravenously, may not sufficiently penetrate certain body sites, and/or are associated with systemic toxicity. Little is known about how to position alternative administration approaches such as inhalational and direct drug delivery routes.

AREAS COVERED

This review provides an updated overview of unconventional drug delivery strategies for managing IFD, focusing on inhalational (to target the lungs) and direct delivery methods to the central nervous system, bone/joint, and eyes. Novel compounds (e.g. opelconazole) and existing antifungals with innovative drug delivery systems currently undergoing clinical trials and/or used off-label in the clinical setting are discussed.

EXPERT OPINION

For both inhalational agents and direct delivery approaches, there are similar challenges that include the absence of: approved formulations for specific administration routes, delivery vehicles that are simple and safe to use whilst maintaining potency and efficiency of delivery, animal models suitable for investigating pharmacokinetic/pharmacodynamic profiles of inhaled antifungals, and consensus on the composite endpoints and intervals for of follow-up in clinical trials. To meet these challenges, cooperation of all stakeholders in drug development and regulation is required.

Diagnosing fungal infections in clinical practice: a narrative review

BACKGROUND

Invasive fungal infections (IFI) present a major medical challenge, with an estimated 6.5 million cases annually, resulting in 3.8 million deaths. Pathogens such as Aspergillus spp. Candida spp. Mucorales spp. Cryptococcus spp. and other fungi species contribute to these infections, posing risks to immunocompromised individuals. Early and accurate diagnosis is crucial for effective treatment and better patient outcomes.

AREAS COVERED

This narrative review provides an overview of the current methods and challenges associated with diagnosing fungal diseases, including invasive aspergillosis and invasive candidiasis, as well as rare and endemic fungal infections. Various diagnostic techniques, including microscopy, culture, molecular diagnostics, and serological tests, are reviewed, highlighting their respective advantages and limitations and role in clinical guidelines. To illustrate, the need for improved diagnostic strategies to overcome existing challenges, such as the low sensitivity and specificity of current tests and the time-consuming nature of traditional culture-based methods, is addressed.

EXPERT OPINION

Current advancements in fungal infection diagnostics have significant implications for healthcare outcomes. Improved strategies like molecular testing and antigen detection promise early detection of fungal pathogens, enhancing patient management. Challenges include global access to advanced technologies and the need for standardized, user-friendly point-of-care diagnostics to improve diagnosis of fungal infections globally.

Extracellular Vesicles from Scedosporium apiospermum Mycelial Cells: Implication for Fungal-Host Interplays

The release of extracellular vesicles (EVs) has been implicated as an alternative transport mechanism for the passage of macromolecules through the fungal cell wall, a phenomenon widely reported in yeasts but poorly explored in mycelial cells. In the present work, we have purified and characterized the EVs released by mycelia of the emerging, opportunistic, widespread and multidrug-resistant filamentous fungus Scedosporium apiospermum. Transmission electron microscopy images and light scattering measurements revealed the fungal EVs, which were observed individually or grouped with heterogeneous morphology, size and electron density. The mean diameter of the EVs, evaluated by the light scattering technique, was 179.7 nm. Overall, the structural stability of S. apiospermum EVs was preserved during incubation under various storage conditions. The lipid, carbohydrate and protein contents were quantified, and the EVs' protein profile was evidenced by SDS-PAGE, revealing proteins with molecular masses ranging from 20 to 118 kDa. Through immunoblotting, ELISA and immunocytochemistry assays, antigenic molecules were evidenced in EVs using a polyclonal serum (called anti-secreted molecules) from a rabbit inoculated with conditioned cell-free supernatant obtained from S. apiospermum mycelial cells. By Western blotting, several antigenic proteins were identified. The ELISA assay confirmed that the anti-secreted molecules exhibited a positive reaction up to a serum dilution of 1:3200. Despite transporting immunogenic molecules, S. apiospermum EVs slightly induced an in vitro cytotoxicity effect after 48 h of contact with either macrophages or lung epithelial cells. Interestingly, the pretreatment of both mammalian cells with purified EVs significantly increased the association index with S. apiospermum conidia. Furthermore, EVs were highly toxic to Galleria mellonella, leading to larval death in a typically dose- and time-dependent manner. Collectively, the results represent the first report of detecting EVs in the S. apiospermum filamentous form, highlighting a possible implication in fungal pathogenesis.

Fungal ball due to a species of the Scedosporium apiospermum complex in a post-tuberculosis patient

BACKGROUND

Scedosporium species are considered emerging pathogens causing illness in immunocompetent and immunocompromised hosts.

CASE REPORT

A case of non-invasive pulmonary (fungal ball) infection by Scedosporium apiospermum complex in a 49-year-old female with bronchiectasis and cavities secondary to tuberculosis is described. The patient had a history of three years of cough and hemoptysis. A computed tomography scan of the thorax revealed the presence of a cavity in the lower lobe of the right lung, associated with bronchiectasis. A combination of surgical debridement and antifungal therapy (voriconazole) was the treatment of choice. Pulmonary resection (right lower lobectomy) was performed, and samples were sent for microbiological culture and histopathological examination; by means of the latter technique, hyphae were shown. The identification of Scedosporium angustum, a phylogenetic species of the S. apiospermum complex, was obtained by amplifying and sequencing the β-tubulin locus. Voriconazole therapy was started at a loading dose of 800mg/12h for the first 24h, followed by 200mg/12h for 6 months. The patient responded favorably to the treatment and remained asymptomatic.

CONCLUSIONS

This case emphasizes the importance of considering Scedosporium species in the differential diagnosis of fungal balls by Aspergillus. .

The top 10 papers on the treatment of invasive fungal infections, 2018-2023

Background

Invasive fungal infections are responsible for a large number of infections in hospitalized patients annually and are responsible for high morbidity and mortality. Familiarity with novel agents or strategies in this area can be challenging.

Objectives

To identify the top 10 manuscripts on the treatment of invasive fungal infections from 2018 to 2023.

Design

Modified Delphi consensus-building technique.

Methods

A three-stage consensus-building approach was used comprised of (1) identifying relevant articles; (2) voting by a panel of experts to establish consensus on the importance of these articles; and (3) finalizing the list of top articles by a small group. Members of the Southeastern Research Group Endeavor network served as content experts. Publications from 2018 to 2023 were evaluated if articles met the following inclusion criteria: (1) published between 2018 and 2023, (2) contained content related to fungal infections, and (3) included an actionable intervention.

Results

A total of 6518 potential publications were assessed. After applying inclusion and exclusion criteria, 82 articles were reviewed. The top 10 publications related to invasive fungal infections, selected by a panel of experts, are summarized in this manuscript and include publications related to the treatment of invasive aspergillosis, candidiasis, and cryptococcosis.

Conclusion

This article highlights the selected publications and may serve as a key resource for teaching and training. Clinicians may also employ these reported interventions to identify new opportunities to optimize antifungal therapeutic strategies within one's institution.