Advances in understanding and managing Scedosporium respiratory infections in patients with cystic fibrosis

ABSTRACT

Introduction: Considered for a long time to be exclusively responsible for chronic localized infections, fungi of the genus Scedosporium have recently received a renewed interest because of their recognition as common colonizing agents of the respiratory tract of patients with cystic fibrosis, and of the description of severe disseminated infections in patients undergoing lung transplantation. Recently, several studies have been carried out on these opportunistic pathogens, which led to some advances in the understanding of their pathogenic mechanisms and in the biological diagnosis of the airway colonization/respiratory infections caused by these fungi.

Areas covered: From a bibliographic search on the Pubmed database, we summarize the current knowledge about the taxonomy of Scedosporium species, the epidemiology of these fungi and their pathogenic mechanisms, and present the improvements in the detection of the airway colonization and diagnosis of Scedosporium respiratory infections, the difficulties in their therapeutic management, and the antifungal drugs in development.

Expert opinion: As described in this review, many advances have been made regarding the taxonomy and ecology of Scedosporium species or the molecular determinants of their pathogenicity, but also in the management of Scedosporium infections, particularly by improving the biological diagnostic and publishing evidence for the efficacy of combined therapy.

KEYWORDS:

• Scedosporium
• cystic fibrosis
• airway colonization
• respiratory infections
• biological diagnosis
• treatment
• ecology
• pathogenic mechanisms

Article highlights

• The genus Scedosporium actually comprises 10 species, five of which having been described in the CF context, with the most common being S. boydii, S. apiospermum, and S. aurantiacum.

• Usually living as soil saprophytes, particularly in human impacted environments, fungi of the genus Scedosporium rank second among the filamentous fungi colonizing the respiratory tract of CF patients.

• Although usually well tolerated, the airway colonization by Scedosporium species may lead to bronchitis and allergic bronchopulmonary mycoses. Additionally, it constitutes a major risk factor for a severe disseminated infection in patients undergoing lung or heart-lung transplantation.

• Detection of this fungal colonization by mycological examination of respiratory secretions should be made as early as possible, at least at registration on the lung transplantation waiting list.

• Inoculation of the clinical samples on agar plates is highly recommended for examination of respiratory secretions, together with the use of a Scedosporium-selective culture medium (Sabouraud-chloramphenicol-cycloheximide for example), and a prolonged incubation time (2 weeks at 35–37°C).

• Although voriconazole remains the first-line treatment to eradicate Scedosporium species, a combination therapy consisting in voriconazole associated to an echinocandin and aerosols of amphotericin B is highly recommended.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This paper was not funded.