Extracellularly Released Molecules by the Multidrug-Resistant Fungal Pathogens Belonging to the Scedosporium Genus: An Overview Focused on Their Ecological Significance and Pathogenic Relevance

Abstract

The multidrug-resistant species belonging to the Scedosporium genus are well recognized as saprophytic filamentous fungi found mainly in human impacted areas and that emerged as human pathogens in both immunocompetent and immunocompromised individuals. It is well recognized that some fungi are ubiquitous organisms that produce an enormous amount of extracellular molecules, including enzymes and secondary metabolites, as part of their basic physiology in order to satisfy their several biological processes. In this context, the molecules secreted by Scedosporium species are key weapons for successful colonization, nutrition and maintenance in both host and environmental sites. These biologically active released molecules have central relevance on fungal survival when colonizing ecological places contaminated with hydrocarbons, as well as during human infection, particularly contributing to the invasion/evasion of host cells and tissues, besides escaping from the cellular and humoral host immune responses. Based on these relevant premises, the present review compiled the published data reporting the main secreted molecules by Scedosporium species, which operate important physiopathological events associated with pathogenesis, diagnosis, antimicrobial activity and bioremediation of polluted environments.

Extracellular Vesicles from Scedosporium apiospermum Mycelial Cells: Implication for Fungal-Host Interplays

“…Infections caused by Scedosporium spp. share similar characteristics with microbial biofilms, including a high density of mycelial cells enclosed in a self-produced extracellular matrix [10][11][12]. In vitro, the high resistance found in Scedosporium biofilms is due to a multitude of mechanisms that operate concurrently, including an increase in cell density, high activity of efflux pumps and the presence of an extracellular polymeric matrix that prevents drug diffusion to fungal cells within biofilms [11,12].…”

“…In this regard, research related to the secretion of extracellular molecules is particularly relevant for understanding fungal pathogenesis [13,14]. The literature on the detection and characterization of extracellularly released molecules by S. apiospermum includes few reports of antigenic molecules, molecules with cytotoxic activities, siderophores and hydrolytic enzymes, especially those belonging to the peptidase class [12,[15][16][17].…”