Brain abscess caused by Scedosporium boydii in a systemic lupus erythematosus patient: A case report and literature review

Emerging Fungal Infections of the Central Nervous System in the Past Decade: A Literature Review

INTRODUCTION

Invasive fungal infections affecting the central nervous system (CNS) are a major health concern worldwide associated with high mortality rates. Their increased incidence is largely due to an increase in the vulnerable immunocompromised population, changing environmental factors, and development of more accurate diagnostic methods. The aim of this article is to identify fungal causes of CNS infections that are recently emerging or have the potential to become emerging pathogens in the near future, as well as their clinical characteristics, including: Candida auris, Trichosporon spp., Blastomyces spp., Sporothrix spp., Talaromyces marneffei, Lomentospora prolificans, and Scedosporium spp.

METHODS

A review of the literature in PubMed in the last ten years was conducted to identify central nervous system infections caused by each of these fungi.

RESULTS

The review identified 10 cases caused by C. auris, 5 cases by Trichosporon spp., 82 cases by Blastomyces spp., 36 cases by Sporothrix spp., 21 cases by T. marneffei, 22 cases by Lomentospora prolificans, and 42 cases by Scedosporium spp.

DISCUSSION

The exact burden of these diseases remains difficult to ascertain, but their apparent rise underscores the urgent need for improved diagnostic, treatment, and management strategies against CNS fungal pathogens to improve outcomes against these life-threatening infections.

Paraclostridium tenue Causing an Anaerobic Brain Abscess Identified by Whole-Metagenome Sequencing: A Case Report

When treating anaerobic brain abscesses, healthcare professionals often face the difficulty of identifying the causal pathogens, necessitating empiric therapies with uncertain efficacy. We present the case of a 57-year-old woman who was admitted to our hospital with a fever and headache. Brain magnetic resonance imaging revealed a hemorrhagic lesion with wall enhancement at the left hemisphere on contrast-enhanced T1-weighted imaging. Cerebrospinal fluid examination showed pleocytosis (23 cells/μL), an elevated protein level (125 mg/dL), and decreased glucose level (51 mg/dL; blood glucose was 128 mg/dL). Intracerebral hemorrhage accompanied by a brain abscess was clinically suspected. The patient received empirical treatment with intravenous meropenem and vancomycin for 2 weeks. However, conventional bacterial culture tests failed to identify the pathogen. We then performed shotgun sequencing and ribosomal multilocus sequence typing, which identified Paraclostridium tenue. Based on this finding, we de-escalated to benzylpenicillin potassium for 4 weeks, leading to a 2.5-year remission of the anaerobic brain abscess. Therefore, Paraclostridium can be a causative pathogen for brain abscesses. Furthermore, whole-metagenome sequencing is a promising method for detecting rare pathogens that are not identifiable by conventional bacterial culture tests. This approach enables more targeted treatment and contributes to achieving long-term remission in clinical settings.

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.

Myocarditis and brain abscess caused by disseminated Scedosporium boydii infection

Scedosporium spp. is a fungal species documented as the cause of infections involving the lungs, brain, and other organ systems in both immunocompetent and immunocompromised individuals. Many cases of this type of fungal infection occurring in immunocompetent patients are subsequent to traumatic injury or drowning events in or near waters containing the fungi. Infection commonly involves the lungs. Rarely, it has been shown to cause disease in the endocardium, but there is even less documentation of the fungi invading the myocardium and causing myocarditis. In this report, we present a case of disseminated Scedosporium boydii infection in a 52-year-old male patient without any known risk factors. He presented with acute onset chest pain and dyspnea accompanied by bilateral lower extremity edema. He was found to have new onset heart failure with reduced ejection fraction, and his hospital course was complicated by pneumonia, disseminated intravascular coagulation (DIC), and brain abscess formation. Multiple blood cultures failed to reveal the source of the infection. At autopsy, septated branching hyphae were identified invading both the myocardium and the cortical brain tissue. DNA sequencing revealed the fungal organisms to be Scedosporium boydii. This case reinforces the importance of autopsies in the clinical setting. It not only established the definitive diagnosis of an unexpected fungal infection, but it also helped to recognize new clinical and pathologic features of this particular fungal organism.

Performance of the beta-glucan test for the diagnosis of invasive fusariosis and scedosporiosis: a meta-analysis

The (1→3)-β-D-glucan (BDG) is a component of the fungal cell wall that can be detected in serum and used as an adjunctive tool for the diagnosis of invasive mold infections (IMI) in patients with hematologic cancer or other immunosuppressive conditions. However, its use is limited by modest sensitivity/specificity, inability to differentiate between fungal pathogens, and lack of detection of mucormycosis. Data about BDG performance for other relevant IMI, such as invasive fusariosis (IF) and invasive scedosporiosis/lomentosporiosis (IS) are scarce. The objective of this study was to assess the sensitivity of BDG for the diagnosis of IF and IS through systematic literature review and meta-analysis. Immunosuppressed patients diagnosed with proven or probable IF and IS, with interpretable BDG data were eligible. A total of 73 IF and 27 IS cases were included. The sensitivity of BDG for IF and IS diagnosis was 76.7% and 81.5%, respectively. In comparison, the sensitivity of serum galactomannan for IF was 27%. Importantly, BDG positivity preceded the diagnosis by conventional methods (culture or histopathology) in 73% and 94% of IF and IS cases, respectively. Specificity was not assessed because of lacking data. In conclusion, BDG testing may be useful in patients with suspected IF or IS. Combining BDG and galactomannan testing may also help differentiating between the different types of IMI.

A Repertoire of Clinical Non-Dermatophytes Moulds

Humans are constantly exposed to micromycetes, especially filamentous fungi that are ubiquitous in the environment. In the presence of risk factors, mostly related to an alteration of immunity, the non-dermatophyte fungi can then become opportunistic pathogens, causing superficial, deep or disseminated infections. With new molecular tools applied to medical mycology and revisions in taxonomy, the number of fungi described in humans is rising. Some rare species are emerging, and others more frequent are increasing. The aim of this review is to (i) inventory the filamentous fungi found in humans and (ii) provide details on the anatomical sites where they have been identified and the semiology of infections. Among the 239,890 fungi taxa and corresponding synonyms, if any, retrieved from the Mycobank and NCBI Taxonomy databases, we were able to identify 565 moulds in humans. These filamentous fungi were identified in one or more anatomical sites. From a clinical point of view, this review allows us to realize that some uncommon fungi isolated in non-sterile sites may be involved in invasive infections. It may present a first step in the understanding of the pathogenicity of filamentous fungi and the interpretation of the results obtained with the new molecular diagnostic tools.