Seborrheic dermatitis and its relationship with Malassezia spp

La dermatitis seborreica (DS) es una enfermedad inflamatoria crónica, con un elevado impacto en la calidad de vida del individuo. Además, DS es una entidad multifactorial que ocurre como respuesta inflamatoria a las levaduras del género Malassezia spp., junto con factores desencadenantes que contribuyen a la fisio¬patología de la enfermedad. Dado que el mecanismo patogénico principal involucra la proliferación e inflamación generada por Malassezia spp., el tratamiento más usado son los agentes tópicos antifúngicos y antiinflamatorios. Sin embargo, se desconocen las consecuencias de eliminar la población de levaduras de la piel, los perfiles de resistencia de Malassezia spp. y la efectividad entre grupos diferentes de medicamentos. Por tanto, en esta revisión de la literatura, resumimos el conocimiento actual sobre la fisiopatología de la enfermedad y el papel de Malassezia sp., así como de las diferentes alternativas de tratamiento antifúngico tanto tópico como oral en el manejo de la DS.Seborrheic dermatitis (SD) is a chronic inflammatory disease that that is difficult to manage and with a high impact on the individual’s quality of life. Besides, it is a multifactorial entity that typically occurs as an inflammatory response to Malassezia species, along with specific triggers that contribute to its pathophysiology. Sin¬ce the primary underlying pathogenic mechanisms include Malassezia proliferation and skin inflammation, the most common treatment includes topical antifungal keratolytics and anti-inflammatory agents. However, the consequences of eliminating the yeast population from the skin, the resistance profiles of Malassezia spp. and the effectivity among different groups of medications are unknown. Thus, in this review, we summarize the current knowledge on the disease´s pathophysio¬logy and the role of Malassezia sp. on it, as well as, the different antifungal treatment alternatives, including topical and oral treatment in the management of SD

Fusarium: more than a node or a foot-shaped basal cell

Recent publications have argued that there are potentially serious consequences for researchers in recognising distinct genera in the terminal fusarioid clade of the family Nectriaceae. Thus, an alternate hypothesis, namely a very broad concept of the genus Fusarium was proposed. In doing so, however, a significant body of data that supports distinct genera in Nectriaceae based on morphology, biology, and phylogeny is disregarded. A DNA phylogeny based on 19 orthologous protein-coding genes was presented to support a very broad concept of Fusarium at the F1 node in Nectriaceae. Here, we demonstrate that re-analyses of this dataset show that all 19 genes support the F3 node that represents Fusarium sensu stricto as defined by F. sambucinum (sexual morph synonym Gibberella pulicaris). The backbone of the phylogeny is resolved by the concatenated alignment, but only six of the 19 genes fully support the F1 node, representing the broad circumscription of Fusarium. Furthermore, a re-analysis of the concatenated dataset revealed alternate topologies in different phylogenetic algorithms, highlighting the deep divergence and unresolved placement of various Nectriaceae lineages proposed as members of Fusarium. Species of Fusarium s. str. are characterised by Gibberella sexual morphs, asexual morphs with thin- or thick-walled macroconidia that have variously shaped apical and basal cells, and trichothecene mycotoxin production, which separates them from other fusarioid genera. Here we show that the Wollenweber concept of Fusarium presently accounts for 20 segregate genera with clear-cut synapomorphic traits, and that fusarioid macroconidia represent a character that has been gained or lost multiple times throughout Nectriaceae. Thus, the very broad circumscription of Fusarium is blurry and without apparent synapomorphies, and does not include all genera with fusarium-like macroconidia, which are spread throughout Nectriaceae (e.g., Cosmosporella, Macroconia, Microcera). In this study four new genera are introduced, along with 18 new species and 16 new combinations. These names convey information about relationships, morphology, and ecological preference that would otherwise be lost in a broader definition of Fusarium. To assist users to correctly identify fusarioid genera and species, we introduce a new online identification database, Fusarioid-ID, accessible at www.fusarium.org. The database comprises partial sequences from multiple genes commonly used to identify fusarioid taxa (act1, CaM, his3, rpb1, rpb2, tef1, tub2, ITS, and LSU). In this paper, we also present a nomenclator of names that have been introduced in Fusarium up to January 2021 as well as their current status, types, and diagnostic DNA barcode data. In this study, researchers from 46 countries, representing taxonomists, plant pathologists, medical mycologists, quarantine officials, regulatory agencies, and students, strongly support the application and use of a more precisely delimited Fusarium (= Gibberella) concept to accommodate taxa from the robust monophyletic node F3 on the basis of a well-defined and unique combination of morphological and biochemical features. This F3 node includes, among others, species of the F. fujikuroi, F. incarnatum-equiseti, F. oxysporum, and F. sambucinum species complexes, but not species of Bisifusarium [F. dimerum species complex (SC)], Cyanonectria (F. buxicola SC), Geejayessia (F. staphyleae SC), Neocosmospora (F. solani SC) or Rectifusarium (F. ventricosum SC). The present study represents the first step to generating a new online monograph of Fusarium and allied fusarioid genera (www.fusarium.org)

Polimorfismos genéticos de aislamientos del género Malassezia obtenidos a partir de pacientes con lesión dermatológica e Individuos sin lesión

Magíster en BiologíaMaestrí

Los hongos como patógenos en humanos

Notas. Ciencias biológicasDurante décadas hemos oído hablar de las infecciones que afectan al ser humano, pero pocas veces las hemos asociado con los hongos. En los últimos años se ha incrementado la tasa de muerte de pacientes VIH positivos afectados por infecciones causadas por hongos oportunistas. Pero ¿cuáles son estos patógenos? Los hongos son organismos eucariotas que se encuentran ampliamente distribuidos en el medioambiente y son capaces de interactuar con el ser humano; sin embargo, pocas especies logran producir infecciones en el hombre. Las micosis, infecciones causadas por hongos, se han clasificado teniendo en cuenta la localización anatómica: superficiales o cutáneas, subcutáneas y profundas, sistémicas o invasoras. Actualmente las investigaciones en este campo están dirigidas a la prevención, el diagnóstico y el tratamiento de las infecciones fúngicas invasoras (IFI). ¿Cuál es la razón? ¿Podrían las IFI afectarnos

In Vitro or In Vivo Models, the Next Frontier for Unraveling Interactions between Malassezia spp. and Hosts. How Much Do We Know?

Malassezia is a lipid-dependent genus of yeasts known for being an important part of the skin mycobiota. These yeasts have been associated with the development of skin disorders and cataloged as a causal agent of systemic infections under specific conditions, making them opportunistic pathogens. Little is known about the host-microbe interactions of Malassezia spp., and unraveling this implies the implementation of infection models. In this mini review, we present different models that have been implemented in fungal infections studies with greater attention to Malassezia spp. infections. These models range from in vitro (cell cultures and ex vivo tissue), to in vivo (murine models, rabbits, guinea pigs, insects, nematodes, and amoebas). We additionally highlight the alternative models that reduce the use of mammals as model organisms, which have been gaining importance in the study of fungal host-microbe interactions. This is due to the fact that these systems have been shown to have reliable results, which correlate with those obtained from mammalian models. Examples of alternative models are Caenorhabditis elegans, Drosophila melanogaster, Tenebrio molitor, and Galleria mellonella. These are invertebrates that have been implemented in the study of Malassezia spp. infections in order to identify differences in virulence between Malassezia species

In Vitro or In Vivo Models, the Next Frontier for Unraveling Interactions between Malassezia spp. and Hosts. How Much Do We Know?

Malassezia is a lipid-dependent genus of yeasts known for being an important part of the skin mycobiota. These yeasts have been associated with the development of skin disorders and cataloged as a causal agent of systemic infections under specific conditions, making them opportunistic pathogens. Little is known about the host-microbe interactions of Malassezia spp., and unraveling this implies the implementation of infection models. In this mini review, we present different models that have been implemented in fungal infections studies with greater attention to Malassezia spp. infections. These models range from in vitro (cell cultures and ex vivo tissue), to in vivo (murine models, rabbits, guinea pigs, insects, nematodes, and amoebas). We additionally highlight the alternative models that reduce the use of mammals as model organisms, which have been gaining importance in the study of fungal host-microbe interactions. This is due to the fact that these systems have been shown to have reliable results, which correlate with those obtained from mammalian models. Examples of alternative models are Caenorhabditis elegans, Drosophila melanogaster, Tenebrio molitor, and Galleria mellonella. These are invertebrates that have been implemented in the study of Malassezia spp. infections in order to identify differences in virulence between Malassezia species

A One Health Perspective to Recognize Fusarium as Important in Clinical Practice

Any strategy that proposes solutions to health-related problems recognizes that people, animals, and the environment are interconnected. Fusarium is an example of this interaction because it is capable of infecting plants, animals, and humans. This review provides information on various aspects of these relations and proposes how to approach fusariosis with a One Health methodology (a multidisciplinary, and multisectoral approach that can address urgent, ongoing, or potential health threats to humans, animals, and the environment). Here, we give a framework to understand infection pathogenesis, through the epidemiological triad, and explain how the broad utilization of fungicides in agriculture may play a role in the treatment of human fusariosis. We assess how plumbing systems and hospital environments might play a role as a reservoir for animal and human infections. We explain the role of antifungal resistance mechanisms in both humans and agriculture. Our review emphasizes the importance of developing interdisciplinary research studies where aquatic animals, plants, and human disease interactions can be explored through coordination and collaborative actions

Back to the Basics: Two Approaches for the Identification and Extraction of Lipid Droplets from Malassezia pachydermatis CBS1879 and Malassezia globosa CBS7966

Malassezia spp. are lipid-dependent yeasts that have been related to skin mycobiota and dermatological and systemic diseases. Study of lipid droplets (LDs) is relevant to elucidate the unknown role of these organelles in Malassezia and to gain a broader overview of lipid metabolism in Malassezia. Here, we standardized two protocols for the analysis of LDs in M. pachydermatis and M. globosa. The first describes co-staining for confocal laser-scanning fluorescence microscopy, and the second details extraction and purification of LDs. The double stain is achieved with three different neutral lipid fluorophores, namely Nile Red, BODIPY™ 493/503, and HCS LipidTOX™ Deep Red Neutral, in combination with Calcofluor White. For LD extraction, cell wall rupture is conducted using Trichoderma harzianum enzymes and cycles of vortexing with zirconium beads. LD purification is performed in a three-step ultracentrifugation process. These standardizations will contribute to the study of the dynamics, morphology, and composition of LDs in Malassezia

New Therapeutic Candidates for the Treatment of Malassezia pachydermatis -Associated Infections

The opportunistic pathogen Malassezia pachydermatis causes bloodstream infections in preterm infants or individuals with immunodeficiency disorders and has been associated with a broad spectrum of diseases in animals such as seborrheic dermatitis, external otitis and fungemia. The current approaches to treat these infections are failing as a consequence of their adverse effects, changes in susceptibility and antifungal resistance. Thus, the identification of novel therapeutic targets against M. pachydermatis infections are highly relevant. Here, Gene Essentiality Analysis and Flux Variability Analysis was applied to a previously reported M. pachydermatis metabolic network to identify enzymes that, when absent, negatively affect biomass production. Three novel therapeutic targets (i.e., homoserine dehydrogenase (MpHSD), homocitrate synthase (MpHCS) and saccharopine dehydrogenase (MpSDH)) were identified that are absent in humans. Notably, L-lysine was shown to be an inhibitor of the enzymatic activity of MpHCS and MpSDH at concentrations of 1 mM and 75 mM, respectively, while L-threonine (1 mM) inhibited MpHSD. Interestingly, L- lysine was also shown to inhibit M. pachydermatis growth during in vitro assays with reference strains and canine isolates, while it had a negligible cytotoxic activity on HEKa cells. Together, our findings form the bases for the development of novel treatments against M. pachydermatis infections

New Therapeutic Candidates for the Treatment of Malassezia pachydermatis -Associated Infections

The opportunistic pathogen Malassezia pachydermatis causes bloodstream infections in preterm infants or individuals with immunodeficiency disorders and has been associated with a broad spectrum of diseases in animals such as seborrheic dermatitis, external otitis and fungemia. The current approaches to treat these infections are failing as a consequence of their adverse effects, changes in susceptibility and antifungal resistance. Thus, the identification of novel therapeutic targets against M. pachydermatis infections are highly relevant. Here, Gene Essentiality Analysis and Flux Variability Analysis was applied to a previously reported M. pachydermatis metabolic network to identify enzymes that, when absent, negatively affect biomass production. Three novel therapeutic targets (i.e., homoserine dehydrogenase (MpHSD), homocitrate synthase (MpHCS) and saccharopine dehydrogenase (MpSDH)) were identified that are absent in humans. Notably, L-lysine was shown to be an inhibitor of the enzymatic activity of MpHCS and MpSDH at concentrations of 1 mM and 75 mM, respectively, while L-threonine (1 mM) inhibited MpHSD. Interestingly, L- lysine was also shown to inhibit M. pachydermatis growth during in vitro assays with reference strains and canine isolates, while it had a negligible cytotoxic activity on HEKa cells. Together, our findings form the bases for the development of novel treatments against M. pachydermatis infections