Acute Scedosporium apiospermum Endobronchial Infection in Cystic Fibrosis

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.

Diagnosis of pulmonary Scedosporium apiospermum infection from bronchoalveolar lavage fluid by metagenomic next-generation sequencing in an immunocompetent female patient with normal lung structure: a case report and literature review

BACKGROUND

Scedosporium apiospermum (S. apiospermum) belongs to the asexual form of Pseudallescheria boydii and is widely distributed in various environments. S. apiospermum is the most common cause of pulmonary infection; however, invasive diseases are usually limited to patients with immunodeficiency.

CASE PRESENTATION

A 54-year-old Chinese non-smoker female patient with normal lung structure and function was diagnosed with pulmonary S. apiospermum infection by metagenomic next-generation sequencing (mNGS) of bronchoalveolar lavage fluid (BALF). The patient was admitted to the hospital after experiencing intermittent right chest pain for 8 months. Chest computed tomography revealed a thick-walled cavity in the upper lobe of the right lung with mild soft tissue enhancement. S. apiospermum was detected by the mNGS of BALF, and DNA sequencing reads were 426. Following treatment with voriconazole (300 mg q12h d1; 200 mg q12h d2-d20), there was no improvement in chest imaging, and a thoracoscopic right upper lobectomy was performed. Postoperative pathological results observed silver staining and PAS-positive oval spores in the alveolar septum, bronchiolar wall, and alveolar cavity, and fungal infection was considered. The patient's symptoms improved; the patient continued voriconazole for 2 months after surgery. No signs of radiological progression or recurrence were observed at the 10-month postoperative follow-up.

CONCLUSION

This case report indicates that S. apiospermum infection can occur in immunocompetent individuals and that the mNGS of BALF can assist in its diagnosis and treatment. Additionally, the combined therapy of antifungal drugs and surgery exhibits a potent effect on the disease.

The Role of Bronchoscopy in the Management of Children With Cystic Fibrosis

BACKGROUND

Currently, no consensus guidelines recommend routine bronchoscopy procedure in cystic fibrosis (CF), as no evidence is available concerning its use as either a diagnostic or therapeutic tool. Its efficacy is controversial, and no randomized controlled prospective trials are available to check its effectiveness. The aims of the present study were to evaluate the effectiveness of bronchoscopy as a diagnostic/therapeutic tool in CF children and adolescents; and to verify the effect of serial bronchoscopy on lung disease progression in subjects with CF not responding to a single procedure.

METHODS

Data of patients who received bronchoscopy at 2 Italian CF centers were collected. Bronchoalveolar lavage was performed during the procedure including airway clearance with mucolytics, inhaled antibiotics, and/or surfactant instillation.

RESULTS

A total of 16 patients in center 1 and 17 in center 2 underwent, respectively, 28 and 23 bronchoscopic procedure in the study period. Five patients in each center underwent >1 procedure. All procedures were generally well tolerated. No patient required admission to the pediatric intensive therapy unit. In 19.6% of bronchoalveolar lavages, growth of Aspergillus fumigatus was evident, although not detected by sputum analyses. After the procedure, an increase in mean percent predicted forced expiratory volume in the 1 second >10% was observed, and a significant decrease in pulmonary exacerbations yearly was evident.

CONCLUSION

Based on the results, we suggest bronchoscopy is not to be considered an obsolete tool, and it remains useful in CF management, although in selected cases. We encourage to support longitudinal observational studies to standardize the procedure, focusing on the choice of drugs to be instilled, modalities and timing of serial bronchoscopy and subsequent follow-up in selected severe clinical conditions.

Detection of the 'Big Five' mold killers of humans: Aspergillus, Fusarium, Lomentospora, Scedosporium and Mucormycetes

Fungi are an important but frequently overlooked cause of morbidity and mortality in humans. Life-threatening fungal infections mainly occur in immunocompromised patients, and are typically caused by environmental opportunists that take advantage of a weakened immune system. The filamentous fungus Aspergillus fumigatus is the most important and well-documented mold pathogen of humans, causing a number of complex respiratory diseases, including invasive pulmonary aspergillosis, an often fatal disease in patients with acute leukemia or in immunosuppressed bone marrow or solid organ transplant recipients. However, non-Aspergillus molds are increasingly reported as agents of disseminated diseases, with Fusarium, Scedosporium, Lomentospora and mucormycete species now firmly established as pathogens of immunosuppressed and immunocompetent individuals. Despite well-documented risk factors for invasive fungal diseases, and increased awareness of the risk factors for life-threatening infections, the number of deaths attributable to molds is likely to be severely underestimated driven, to a large extent, by the lack of readily accessible, cheap, and accurate tests that allow detection and differentiation of infecting species. Early diagnosis is critical to patient survival but, unlike Aspergillus diseases, where a number of CE-marked or FDA-approved biomarker tests are now available for clinical diagnosis, similar tests for fusariosis, scedosporiosis and mucormycosis remain experimental, with detection reliant on insensitive and slow culture of pathogens from invasive bronchoalveolar lavage fluid, tissue biopsy, or from blood. This review examines the ecology, epidemiology, and contemporary methods of detection of these mold pathogens, and the obstacles to diagnostic test development and translation of novel biomarkers to the clinical setting.

The diagnosis and management of respiratory tract fungal infection in cystic fibrosis: A UK survey of current practice

Aspergillus fumigatus is commonly found in the airways of patients with cystic fibrosis (CF), and allergic bronchopulmonary aspergillosis (ABPA) is the most recognized associated clinical condition. However, accurate diagnosis remains challenging, and there is a paucity of clinical trials to guide clinical management of fungal disease. The aim of this survey was to assess the variability in current practice across the UK in diagnosis and management of fungal lung disease in CF patients. A 21 question anonymous online survey was sent to 94 paediatric and adult CF consultants in the UK. The response rate was 60.6% (32 adult physicians, 25 pediatricians) with 55 full and 2 partially completed surveys. For a first diagnosis of ABPA 20 (35.1%) treat with prednisolone alone, 38 (66.7%) use prednisolone with itraconazole and 2 (3.5%) choose voriconazole. Only 5 (8.8%) treat with prednisolone alone for a 1st relapse, 33 (58%) used prednisolone with itraconazole. To reduce treatment, 21 (36.8%) decrease steroids to zero over time and maintain azole therapy, 18 (31.6%) stop the azole and steroid after a fixed time, and 5 (8.8%) stop the azole after a fixed time and maintain a small steroid dose. Thirty-eight (66.7%) respondents believe Aspergillus colonization of the airway can cause clinical deterioration, and 37 (66.1%) would treat this. Scedosporium apiospermum infection has been diagnosed and treated by 35 (61.4%) of respondents. Results of this survey highlight the variance in clinical practice and the limited evidence available to guide management of fungal infection in CF.

Developing collaborative works for faster progress on fungal respiratory infections in cystic fibrosis

Cystic fibrosis (CF) is the major genetic inherited disease in Caucasian populations. The respiratory tract of CF patients displays a sticky viscous mucus, which allows for the entrapment of airborne bacteria and fungal spores and provides a suitable environment for growth of microorganisms, including numerous yeast and filamentous fungal species. As a consequence, respiratory infections are the major cause of morbidity and mortality in this clinical context. Although bacteria remain the most common agents of these infections, fungal respiratory infections have emerged as an important cause of disease. Therefore, the International Society for Human and Animal Mycology (ISHAM) has launched a working group on Fungal respiratory infections in Cystic Fibrosis (Fri-CF) in October 2006, which was subsequently approved by the European Confederation of Medical Mycology (ECMM). Meetings of this working group, comprising both clinicians and mycologists involved in the follow-up of CF patients, as well as basic scientists interested in the fungal species involved, provided the opportunity to initiate collaborative works aimed to improve our knowledge on these infections to assist clinicians in patient management. The current review highlights the outcomes of some of these collaborative works in clinical surveillance, pathogenesis and treatment, giving special emphasis to standardization of culture procedures, improvement of species identification methods including the development of nonculture-based diagnostic methods, microbiome studies and identification of new biological markers, and the description of genotyping studies aiming to differentiate transient carriage and chronic colonization of the airways. The review also reports on the breakthrough in sequencing the genomes of the main Scedosporium species as basis for a better understanding of the pathogenic mechanisms of these fungi, and discusses treatment options of infections caused by multidrug resistant microorganisms, such as Scedosporium and Lomentospora species and members of the Rasamsonia argillacea species complex.

Scedosporium and Lomentospora: an updated overview of underrated opportunists

Species of Scedosporium and Lomentospora are considered as emerging opportunists, affecting immunosuppressed and otherwise debilitated patients, although classically they are known from causing trauma-associated infections in healthy individuals. Clinical manifestations range from local infection to pulmonary colonization and severe invasive disease, in which mortality rates may be over 80%. These unacceptably high rates are due to the clinical status of patients, diagnostic difficulties, and to intrinsic antifungal resistance of these fungi. In consequence, several consortia have been founded to increase research efforts on these orphan fungi. The current review presents recent findings and summarizes the most relevant points, including the Scedosporium/Lomentospora taxonomy, environmental distribution, epidemiology, pathology, virulence factors, immunology, diagnostic methods, and therapeutic strategies.

Pseudallescheria/Scedosporium complex species: From saprobic to pathogenic fungus

Scedosporiosis is an emerging fungal infection caused by Pseudallescheria/Scedosporium complex species (PSC). This pathogen has been drawn significant interest in recent years due to its worldwide prevalence, the seriousness of its infection, associated with high mortality in both immunocompromised and immunocompetent hosts and its cryptic ecology, distribution and epidemiology across the globe. These species complexes can be found in environments impacted by human. The purpose of this review is to describe the characteristics, mode of transmission, ecology, prevalence, global epidemiology of this fungal group in order to increase the awareness of among clinicians and microbiologists, especially in regions with high endemic, as well as to promote further research on all of its aspects.

Fungus-Specific CD4 T Cells as Specific Sensors for Identification of Pulmonary Fungal Infections

Patients with cystic fibrosis (CF) suffer from chronic lung infections, caused by bacterial, viral or fungal pathogens, which determine morbidity and mortality. The contribution of individual pathogens to chronic disease and acute lung exacerbations is often difficult to determine due to the complex composition of the lung microbiome in CF. In particular, the relevance of fungal pathogens in CF airways remains poorly understood due to limitations of current diagnostics to identify the presence of fungal pathogens and to resolve the individual host-pathogen interaction status. T-lymphocytes play an essential role in host defense against pathogens, but also in inappropriate immune reactions such as allergies. They have the capacity to specifically recognize and discriminate the different pathogens and orchestrate a diverse array of effector functions. Thus, the analysis of the fungus-specific T cell status of an individual can in principle provide detailed information about the identity of the fungal pathogen(s) encountered and the actual fungus-host interaction status. This may allow to classify patients, according to appropriate (protective) or inappropriate (pathology-associated) immune reactions against individual fungal pathogens. However, T cell-based diagnostics are currently not part of the clinical routine. The identification and characterization of fungus-specific T cells in health and disease for diagnostic purposes are associated with significant challenges. Recent technological developments in the field of fungus-specific T helper cell detection provide new insights in the host T cell-fungus interaction. In this review, we will discuss basic principles and the potential of T cell-based diagnostics, as well as the perspectives and further needs for use of T cells for improved clinical diagnostics of fungal diseases.

Fungal Pathogens in CF Airways: Leave or Treat?

Chronic airway infection plays an essential role in the progress of cystic fibrosis (CF) lung disease. In the past decades, mainly bacterial pathogens, such as Pseudomonas aeruginosa, have been the focus of researchers and clinicians. However, fungi are frequently detected in CF airways and there is an increasing body of evidence that fungal pathogens might play a role in CF lung disease. Several studies have shown an association of fungi, particularly Aspergillus fumigatus and Candida albicans, with the course of lung disease in CF patients. Mechanistically, in vitro and in vivo studies suggest that an impaired immune response to fungal pathogens in CF airways renders them more susceptible to fungi. However, it remains elusive whether fungi are actively involved in CF lung disease pathologies or whether they rather reflect a dysregulated airway colonization and act as microbial bystanders. A key issue for dissecting the role of fungi in CF lung disease is the distinction of dynamic fungal-host interaction entities, namely colonization, sensitization or infection. This review summarizes key findings on pathophysiological mechanisms and the clinical impact of fungi in CF lung disease.

Scedosporium apiospermum complex in cystic fibrosis; should we treat?

Species of the Scedosporium apiospermum complex are the second most frequent filamentous fungi after Aspergillus fumigatus that can be found in cystic fibrosis (CF). Mixed colonisation by S. apiospermum complex and A. fumigatus is also quite common. In this study we summarise all CF patients who were colonised by S. apiospermum complex during their childhood and we present two CF patients who were treated as fungal bronchitis due to S. apiospermum complex. The medical records of 400 CF patients were reviewed in order to identify those with positive respiratory cultures for S. apiospermum complex. Scedosporium apiospermum complex was isolated in 10 CF patients and six of them had more than two positive sputum cultures during the study period. By the time of first isolation, the median age was 14.5 years, the median BMI was 19.41 kg/m² , the median predicted FEV₁ % was 78.65% and six patients had a history of A. fumigatus isolation. Two patients presented symptoms of infection while they were colonised by S. apiospermum complex. A rapid remission of their symptoms was observed only when antifungal therapy was administered. Antifungal treatment should be considered in CF patients who present symptoms of infection not responding to antibacterial therapy and S. apiospermum complex is persistently growing in sputum cultures.

Pathogenesis of Fungal Infections in Cystic Fibrosis

For a long time, the microbiology of cystic fibrosis has been focussed on Pseudomonas aeruginosa and associated Gram-negative pathogens. An increasing body of evidence has been compiled demonstrating an important role for moulds and yeasts within this complex patient group. Whether or not fungi are active participants, spectators or transient passersby remain to be elucidated. However, functionally, they do appear to play a contributory role in pathogenesis, albeit we do not know if this is a direct or indirect effect. The following review examines some of the key evidence for the role of fungi in CF pathogenesis.