Scedosporium and Lomentospora Infections: Contemporary Microbiological Tools for the Diagnosis of Invasive Disease

Abstract

Scedosporium/Lomentospora fungi are increasingly recognized pathogens. As these fungi are resistant to many antifungal agents, early diagnosis is essential for initiating targeted drug therapy. Here, we review the microbiological tools for the detection and diagnosis of invasive scedosporiosis and lomentosporiosis. Of over 10 species, Lomentospora prolificans, Scedosporium apiospermum, S. boydii and S. aurantiacum cause the majority of infections. Definitive diagnosis relies on one or more of visualization, isolation or detection of the fungus from clinical specimens by microscopy techniques, culture and molecular methods such as panfungal PCR or genus-/species-specific multiplex PCR. For isolation from respiratory tract specimens, selective media have shown improved isolation rates. Species identification is achieved by macroscopic and microscopic examination of colonies, but species should be confirmed by ITS with or without β-tubulin gene sequencing or other molecular methods. Matrix-assisted laser desorption ionization-time of flight mass spectrometry databases are improving but may need supplementation by in-house spectra for species identification. Reference broth microdilution methods is preferred for antifungal susceptibility testing. Next-generation sequencing technologies have good potential for characterization of these pathogens. Diagnosis of Scedosporium/Lomentospora infections relies on multiple approaches encompassing both phenotypic- and molecular-based methods.

Coronavirus Disease 2019–Associated Invasive Fungal Infection

“…Diagnostic approaches to Mucorales and other mold infections in COVID-19 follow similar principles to those in other populations and are detailed in recent guidelines [ 86 , 90 , 91 ]. A high index of suspicion in at-risk groups should prompt appropriate imaging and examination of clinical specimens (sputum, tracheal aspirates, BAL fluid, skin lesions) by histology, direct microscopy, culture for fungi, and employment of non-culture-based approaches, if available.…”

Invasive and Subcutaneous Infections Caused by Filamentous Fungi: Report from a Portuguese Multicentric Surveillance Program

“…Scedosporium apiospermum (complex) was the only species of this genus that was detected in the studied subcutaneous infections. This complex of species is underlined as an emerging opportunistic filamentous fungi, with several reports described [ 41 , 42 ]. Treatment of Scedosporium infections is especially challenging due to the high levels of antifungal resistance [ 35 , 43 ].…”

Fungal Infections Other Than Invasive Aspergillosis in COVID-19 Patients

“…The diagnosis of non-Aspergillus mould infections follows similar principles to those for other IFDs [98,105,106]. Clinical suspicion should prompt appropriate imaging and examination of clinical specimens (sputum, tracheal aspirates, BAL fluid, skin lesions) by histology, direct microscopy, culture for fungi, and employment of antigen and NAATbased approaches.…”