Pseudallescheria boydii (Scedosporium species) in 3 Lung Transplant Recipients: Computed Tomography Findings and Literature Review

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.

Non-Aspergillus Hyaline Molds: A Host-Based Perspective of Emerging Pathogenic Fungi Causing Sinopulmonary Diseases

The incidence of invasive sino-pulmonary diseases due to non-Aspergillus hyaline molds is increasing due to an enlarging and evolving population of immunosuppressed hosts as well as improvements in the capabilities of molecular-based diagnostics. Herein, we review the following opportunistic pathogens known to cause sinopulmonary disease, the most common manifestation of hyalohyphomycosis: Fusarium spp., Scedosporium spp., Lomentospora prolificans, Scopulariopsis spp., Trichoderma spp., Acremonium spp., Paecilomyces variotii, Purpureocillium lilacinum, Rasamsonia argillacea species complex, Arthrographis kalrae, and Penicillium species. To facilitate an understanding of the epidemiology and clinical features of sino-pulmonary hyalohyphomycoses in the context of host immune impairment, we utilized a host-based approach encompassing the following underlying conditions: neutropenia, hematologic malignancy, hematopoietic and solid organ transplantation, chronic granulomatous disease, acquired immunodeficiency syndrome, cystic fibrosis, and healthy individuals who sustain burns, trauma, or iatrogenic exposures. We further summarize the pre-clinical and clinical data informing antifungal management for each pathogen and consider the role of adjunctive surgery and/or immunomodulatory treatments to optimize patient outcome.

Rapid Diagnosis of Central Nervous System Scedosporiosis by Specific Quantitative Polymerase Chain Reaction Applied to Formalin-Fixed, Paraffin-Embedded Tissue

Scedosporium (S.) apiospermum is a typical mold causing cerebral abscesses, often after near-drowning. Infections are associated with high morbidity and mortality due to diagnostic challenges including the need for prolonged incubation of cultures. In addition, histopathological differentiation from other filamentous fungi, including Aspergillus fumigatus, may not be possible, excluding early specific diagnosis and targeted therapy. Polymerase chain reaction (PCR) on tissue samples can rapidly identify fungi, leading to an earlier adequate treatment. Due to an extensive spectrum of causative fungi, broad-range PCRs with amplicon sequencing have been endorsed as the best DNA amplification strategy. We herein describe a case with brain abscesses due to S. apiospermum in a 66-year-old immunocompromised female patient. While broad-range PCR failed to identify a fungal pathogen from a cerebral biopsy demonstrating hyaline mold hyphae, specific quantitative PCR (qPCR) identified Scedosporium and ruled out Aspergillus, the most prevalent agent of central nervous system mold infection. A panel of specific qPCR assays, guided by the morphology of fungal elements in tissue or as a multiplex assay, may be a successful molecular approach to identify fungal agents of brain abscesses. This also applies in the presence of negative broad-range fungal PCR, therefore providing diagnostic and therapeutic potential for early specific management and improvement of patient clinical outcome.

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.

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.

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

BACKGROUND

Scedosporium species and Lomentospora prolificans (S/L) are the second most common causes of invasive mold infections following Aspergillus in lung transplant recipients.

METHODS

We assessed the current practices on management of S/L colonization/infection of the lower respiratory tract before and after lung transplantation in a large number of lung transplant centers through an international practice survey from October 2016 to March 2017.

RESULTS

A total of 51 respondents from 45 lung transplant centers (17 countries, 4 continents) answered the survey (response rate 58%). S/L colonization was estimated to be detected in candidates by 48% of centers. Only 18% of the centers used a specific medium to detect S/L colonization. Scedosporium spp. colonization was a contraindication to transplantation in 10% of centers whereas L prolificans was a contraindication in 31%; 22% of centers declared having had 1-5 recipients infected with S/L in the past 5 years.

CONCLUSIONS

This survey gives an overview of the current practices regarding S/L colonization and infection in lung transplant centers worldwide and underscores the need of S/L culture procedure standardization before implementing prospective studies.

Pseudallescheria Boydii pneumonia in an immunocompetent host

Background:

Pseudallescheria boydii pneumonia is rarely reported among immunocompetent patients.

Case Report:

We report a case of a 62 year old white female with pseudallescheria boydii pneumonia. The patient was non-immunocompromised, had a history of mycobacterium avium complex (MAC) infection prior to presentation. After successful response to initial antitubercular therapy, the patient developed recurrent symptoms and bibasilar nodular infiltrates. Second line therapy for MAC failed to improve symptomatology. Pseudallescheria boydii pneumonia was diagnosed from a bronchoscopic biopsy. Treatment with voriconazole resolved her symptomatology and radiological infiltrates.

Conclusions:

This case highlights the importance of a high index of suspicion for superimposed fungal infections in patients who are refractory to medical treatment of bacterial pneumonitis such as MAC. Further diagnostic interventions are encouraged when insufficient clinical improvement is observed. Prompt initiation of an antifungal regimen is warranted.

SCEDOSPORIUM INFECTION IN A PATIENT WITH ANTI-TNFα THERAPY

Patients on anti-TNFα therapy are at increased risk for rare opportunistic infections. Here we are reporting a case of Scedosporium apiospermum infection in a patient treated with anti-TNF for 5 years. Patients on anti-TNFα need close follow-up and clinicians should be suspicious for atypical infections in these immunocompromised hosts.

Lung scedosporiosis in human immunodeficiency virus/acquired immunodeficiency syndrome

A 31-year-old African American woman with human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) (recent CD4 count of 66/mm) presented to the emergency room with a tension pneumothorax that required an emergent chest tube placement. Computed tomography scan showed fungus balls in multiple lung cavities and surrounding infiltrates. The patient showed remarkable improvement with voriconazole suggesting aspergillosis. However, the patient was serologically negative for Aspergillus and other common fungal infections. Because of a persistent air leak, surgical intervention was needed. The histological finding was consistent with invasive mycosis, and cultures were positive for Scedosporium apiospermum. Literature review showed that, among patients with HIV/AIDS, Scedosporium can present from focal localized to systemic disease, is resistant to traditional antifungal agents, and may respond to prompt management with voriconazole.