Remarkable Phenotypic Virulence Factors of Microsporum canis and Their Associated Genes: A Systematic Review.

Microsporum canis is a widely distributed dermatophyte, which is among the main etiological agents of dermatophytosis in humans and domestic animals. This fungus invades, colonizes and nourishes itself on the keratinized tissues of the host through various virulence factors. This review will bring together the known information about the mechanisms, enzymes and their associated genes relevant to the pathogenesis processes of the fungus and will provide an overview of those virulence factors that should be better studied to establish effective methods of prevention and control of the disease. Public databases using the MeSH terms "Microsporum canis", "virulence factors" and each individual virulence factor were reviewed to enlist a series of articles, from where only original works in English and Spanish that included relevant information on the subject were selected. Out of the 147 articles obtained in the review, 46 were selected that reported virulence factors for M. canis in a period between 1988 and 2023. The rest of the articles were discarded because they did not contain information on the topic (67), some were written in different languages (3), and others were repeated in two or more databases (24) or were not original articles (7). The main virulence factors in M. canis are keratinases, fungilisins and subtilisins. However, less commonly reported are biofilms or dipeptidylpeptidases, among others, which have been little researched because they vary in expression or activity between strains and are not considered essential for the infection and survival of the fungus. Although it is known that they are truly involved in resistance, infection and metabolism, we recognize that their study could strengthen the knowledge of the pathogenesis of M. canis with the aim of achieving effective treatments, as well as the prevention and control of infection.

Histoplasma capsulatum Isolated from Tadarida brasiliensis Bats Captured in Mexico Form a Sister Group to North American Class 2 Clade.

Histoplasma capsulatum is a dimorphic fungus associated with respiratory and systemic infections in mammalian hosts that have inhaled infective mycelial propagules. A phylogenetic reconstruction of this pathogen, using partial sequences of arf, H-anti, ole1, and tub1 protein-coding genes, proposed that H. capsulatum has at least 11 phylogenetic species, highlighting a clade (BAC1) comprising three H. capsulatum isolates from infected bats captured in Mexico. Here, relationships for each individual locus and the concatenated coding regions of these genes were inferred using parsimony, maximum likelihood, and Bayesian inference methods. Coalescent-based analyses, a concatenated sequence-types (CSTs) network, and nucleotide diversities were also evaluated. The results suggest that six H. capsulatum isolates from the migratory bat Tadarida brasiliensis together with one isolate from a Mormoops megalophylla bat support a NAm 3 clade, replacing the formerly reported BAC1 clade. In addition, three H. capsulatum isolates from T. brasiliensis were classified as lineages. The concatenated sequence analyses and the CSTs network validate these findings, suggesting that NAm 3 is related to the North American class 2 clade and that both clades could share a recent common ancestor. Our results provide original information on the geographic distribution, genetic diversity, and host specificity of H. capsulatum.

Molecular identification of yeasts from the order Trichosporonales causing superficial infections.

BACKGROUND: The molecular reclassification of the order Trichosporonales placed the medically relevant Trichosporon species into three genera of the family Trichosporonaceae: Cutaneotrichosporon, Trichosporon, and Apiotrichum. From the clinical and epidemiological standpoint, it is important to identify any species of the family Trichosporonaceae because they present different antifungal susceptibility profiles. In Mexico, little is known about trichosporonosis etiology because the fungi are identified through phenotypic methods. AIMS: To identify at a molecular level 12 yeast isolates morfologically compatible with Trichosporon, obtained from patients with superficial infections. METHODS: The yeast isolates were obtained from patients with white piedra, onychomycosis, and hand and foot dermatomycosis, and were identified morphologically and genotypically (sequencing of the IGS1 region and phylogenetic analysis using the Maximum Likelihood Method). The phylogenetic analysis included 40 yeast sequences from the order Trichosporonales and one from Cryptococcus neoformans as outgroup. RESULTS: Based on the molecular analysis, we identified three (25%) Trichosporon inkin isolates, two (16.7%) Trichosporon asteroides, two (16.7%) Cutaneotrichosporon mucoides, and one each (8.3%) of Trichosporon aquatile, Trichosporon asahii, Apiotrichum montevideense, Cutaneotrichosporon cutaneum, and Cutaneotrichosporon jirovecii. CONCLUSIONS: The molecular characterization of the isolates showed a broad diversity of species within the order Trichosporonales, particularly among onychomycosis. It is essential to identify these yeasts at the species level to delve into their epidemiology.

Antifungal Resistance in Candida auris: Molecular Determinants.

Since Candida auris integrates strains resistant to multiple antifungals, research has been conducted focused on knowing which molecular mechanisms are involved. This review aims to summarize the results obtained in some of these studies. A search was carried out by consulting websites and online databases. The analysis indicates that most C. auris strains show higher resistance to fluconazole, followed by amphotericin B, and less resistance to 5-fluorocytosine and caspofungin. In C. auris, antifungal resistance to amphotericin B has been linked to an overexpression of several mutated ERG genes that lead to reduced ergosterol levels; fluconazole resistance is mostly explained by mutations identified in the ERG11 gene, as well as a higher number of copies of this gene and the overexpression of efflux pumps. For 5-fluorocytosine, it is hypothesized that the resistance is due to mutations in the FCY2, FCY1, and FUR1 genes. Resistance to caspofungin has been associated with a mutation in the FKS1 gene. Finally, resistance to each antifungal is closely related to the type of clade to which the strain belongs.

Novel clinical and dual infection by Histoplasma capsulatum genotypes in HIV patients from Northeastern, Brazil.

Histoplasmosis is a worldwide-distributed deep mycosis that affects healthy and immunocompromised hosts. Severe and disseminated disease is especially common in HIV-infected patients. At least 11 phylogenetic species are recognized and the majority of diversity is found in Latin America. The northeastern region of Brazil has one of the highest HIV/AIDS prevalence in Latin America and Ceará State has one of the highest death rates due to histoplasmosis in the world, where the mortality rate varies between 33-42%. The phylogenetic distribution and population genetic structure of 51 clinical isolates from Northeast Brazil was studied. For that morphological characteristics, exoantigens profile, and fungal mating types were evaluated. The genotypes were deduced by a MSLT in order to define local population structure of this fungal pathogen. In addition, the relationships of H. capsulatum genotypes with clinically relevant phenotypes and clinical aspects were investigated. The results suggest two cryptic species, herein named population Northeast BR1 and population Northeast BR2. These populations are recombining, exhibit a high level of haplotype diversity, and contain different ratios of mating types MAT1-1 and MAT1-2. However, differences in phenotypes or clinical aspects were not observed within these new cryptic species. A HIV patient can be co-infected by two or more genotypes from Northeast BR1 and/or Northeast BR2, which may have significant impact on disease progression due to the impaired immune response. We hypothesize that co-infections could be the result of multiple exposure events and may indicate higher risk of disseminated histoplasmosis, especially in HIV infected patients.

Histoplasma capsulatum and Pneumocystis jirovecii coinfection in hospitalized HIV and non-HIV patients from a tertiary care hospital in Mexico.

BACKGROUND: Histoplasma capsulatum and Pneumocystis jirovecii are respiratory fungal pathogens that principally cause pulmonary disease. Coinfection with both pathogens is scarcely reported. This study detected this coinfection using specific molecular methods for each fungus in the bronchoalveolar lavage (BAL) of patients from a tertiary care hospital. MATERIALS AND METHODS: BAL samples from 289 hospitalized patients were screened by PCR with specific markers for H. capsulatum (Hcp100) and P. jirovecii (mtLSUrRNA and mtSSUrRNA). The presence of these pathogens was confirmed by the generated sequences for each marker. The clinical and laboratory data for the patients were analyzed using statistical software. RESULTS: The PCR findings separated three groups of patients, where the first was represented by 60 (20.8%) histoplasmosis patients, the second by 45 (15.6%) patients with pneumocystosis, and the last group by 12 (4.2%) patients with coinfection. High similarity among the generated sequences of each species was demonstrated by BLASTn and neighbor-joining algorithms. The estimated prevalence of H. capsulatum and P. jirovecii coinfection was higher in HIV patients.

Mixed infection by Histoplasma capsulatum isolates with different mating types in Brazilian AIDS-patients.

Mixed infection by Histoplasma capsulatum isolates with different mating types, in AIDS-patients are described in this study. Morphological, mating type-specific PCR assay and multilocus sequencing type analysis of H. capsulatum isolates recovered from two Brazilian AIDS-patients were performed. Five H. capsulatum isolates were recovered at different times from the two patients. Three isolates were obtained from bone marrow (day 1 - CE0411) and buffy coat cultures (day 1 - CE0311; day 2 - CE0511) of patient 1, and two isolates were isolated from buffy coat cultures (day 3 - CE2813; day 12 - CE2513) of patient 2. The mycelial colonies depicted different textures and pigmentation features. Dimorphic conversion to the yeast-phase in ML-Gema medium was achieved in all isolates. MAT1-1 idiomorph was identified in CE0311, CE0411 and CE2813 isolates; MAT1-2 idiomorph was found in CE0511 and CE2513 isolates. These H. capsulatum isolates were grouped within LAm A clade, highlighting that CE0311 and CE0411 isolates formed a subgroup supported by a high bootstrap value. The CE0511, CE2513, and CE2813 isolates clustered together with a Brazilian H151 isolate. This research reports mixed infections caused by H. capsulatum isolates with different mating types in Brazilian AIDS-patients for the first time in the literature.

The importance of molecular analyses for understanding the genetic diversity of Histoplasma capsulatum: an overview / Importancia de los análisis moleculares en la comprensión de la diversidad genética de Histoplasma capsulatum: revisión

Advances in the classification of the human pathogen Histoplasma capsulatum (H. capsulatum) (ascomycete) are sustained by the results of several genetic analyses that support the high diversity of this dimorphic fungus. The present mini-review highlights the great genetic plasticity of H. capsulatum. Important records with different molecular tools, mainly single- or multi-locus sequence analyses developed with this fungus, are discussed. Recent phylogenetic data with a multi-locus sequence analysis using 5 polymorphic loci support a new clade and/or phylogenetic species of H. capsulatum for the Americas, which was associated with fungal isolates obtained from the migratory bat Tadarida brasiliensis. This manuscript is part of the series of works presented at the "V International Workshop: Molecular genetic approaches to the study of human pathogenic fungi" (Oaxaca, Mexico, 2012) (AU)

Los resultados de diversos análisis genéticos que respaldan la alta diversidad de este hongo dimorfo confirman los progresos en la clasificación del patógeno humano Histoplasma capsulatum (H. capsulatum) (un ascomiceto). La presente revisión destaca la importante plasticidad genética de H. capsulatum. Se describen los datos importantes con los diferentes instrumentos moleculares, sobre todo, los análisis de las secuencias individuales o multi-loci establecidos con este hongo.Datos filogenéticos recientes con un análisis multi-loci de secuencias utilizando 5 loci polimorfos respaldan un nuevo clado y/o especie filogenética de H. capsulatum del continente americano, asociado a aislamientos fúngicos obtenidos del murciélago migratorio Tadarida brasiliensis.Este artículo forma parte de una serie de estudios presentados en el «V International Workshop: Molecular genetic approaches to the study of human pathogenic fungi» (Oaxaca, México, 2012) (AU)

Genetic diversity of Histoplasma and Sporothrix complexes based on sequences of their ITS1-5.8S-ITS2 regions from the BOLD System / Diversidad genética de los complejos Histoplasma y Sporothrix en función de las secuencias de sus regiones ITS1-5.8S-ITS2 del BOLD System

High sensitivity and specificity of molecular biology techniques have proven usefulness for the detection, identification and typing of different pathogens. The ITS (Internal Transcribed Spacer) regions of the ribosomal DNA are highly conserved non-coding regions, and have been widely used in different studies including the determination of the genetic diversity of human fungal pathogens. This article wants to contribute to the understanding of the intra- and interspecific genetic diversity of isolates of the Histoplasma capsulatum and Sporothrix schenckii species complexes by an analysis of the available sequences of the ITS regions from different sequence databases. ITS1-5.8S-ITS2 sequences of each fungus, either deposited in GenBank, or from our research groups (registered in the Fungi Barcode of Life Database), were analyzed using the maximum likelihood (ML) method. ML analysis of the ITS sequences discriminated isolates from distant geographic origins and particular wild hosts, depending on the fungal species analyzed. This manuscript is part of the series of works presented at the "V International Workshop: Molecular genetic approaches to the study of human pathogenic fungi" (Oaxaca, Mexico, 2012 (AU)

Las técnicas de biología molecular han proporcionado instrumentos de alta sensibilidad y especificidad, útiles para la detección, identificación y tipificación de diferentes patógenos. Las regiones ITS (Internal Transcribed Spacer) del ADN ribosómico están altamente conservadas y no son codificantes. Estas regiones se han utilizado ampliamente en diferentes tipos de estudios, incluida la determinación de la diversidad genética de hongos patógenos del ser humano. La finalidad de este artículo es contribuir al conocimiento de la diversidad genética intra- e interespecífica de aislamientos de los complejos de Histoplasma capsulatum y Sporothrix schenckii a través del análisis de las secuencias disponibles de las regiones ITS en distintos bancos de secuencias. Las secuencias de las regiones ITS1-5.8S-ITS2, de cada hongo, depositadas en el GenBank, junto con las obtenidas por nuestros grupos de investigación (depositadas en la Fungal Barcoding of Life Database), se analizaron con el método de máxima probabilidad (ML, por sus siglas en inglés). El análisis ML de las secuencias de las regiones ITS discriminó aislamientos de orígenes geográficos distantes y de huéspedes salvajes particulares, de acuerdo con la especie fúngica analizada.Este artículo forma parte de una serie de estudios presentados en el «V International Workshop: Molecular genetic approaches to the study of human pathogenic fungi» (Oaxaca, México, 2012) (AU)

Genetic diversity of Histoplasma and Sporothrix complexes based on sequences of their ITS1-5.8S-ITS2 regions from the BOLD System.

High sensitivity and specificity of molecular biology techniques have proven usefulness for the detection, identification and typing of different pathogens. The ITS (Internal Transcribed Spacer) regions of the ribosomal DNA are highly conserved non-coding regions, and have been widely used in different studies including the determination of the genetic diversity of human fungal pathogens. This article wants to contribute to the understanding of the intra- and interspecific genetic diversity of isolates of the Histoplasma capsulatum and Sporothrix schenckii species complexes by an analysis of the available sequences of the ITS regions from different sequence databases. ITS1-5.8S-ITS2 sequences of each fungus, either deposited in GenBank, or from our research groups (registered in the Fungi Barcode of Life Database), were analyzed using the maximum likelihood (ML) method. ML analysis of the ITS sequences discriminated isolates from distant geographic origins and particular wild hosts, depending on the fungal species analyzed. This manuscript is part of the series of works presented at the "V International Workshop: Molecular genetic approaches to the study of human pathogenic fungi" (Oaxaca, Mexico, 2012).

The importance of molecular analyses for understanding the genetic diversity of Histoplasma capsulatum: an overview.

Advances in the classification of the human pathogen Histoplasma capsulatum (H. capsulatum) (ascomycete) are sustained by the results of several genetic analyses that support the high diversity of this dimorphic fungus. The present mini-review highlights the great genetic plasticity of H. capsulatum. Important records with different molecular tools, mainly single- or multi-locus sequence analyses developed with this fungus, are discussed. Recent phylogenetic data with a multi-locus sequence analysis using 5 polymorphic loci support a new clade and/or phylogenetic species of H. capsulatum for the Americas, which was associated with fungal isolates obtained from the migratory bat Tadarida brasiliensis. This manuscript is part of the series of works presented at the "V International Workshop: Molecular genetic approaches to the study of human pathogenic fungi" (Oaxaca, Mexico, 2012).

Frequency and genetic diversity of the MAT1 locus of Histoplasma capsulatum isolates in Mexico and Brazil.

The MAT1-1 and MAT1-2 idiomorphs associated with the MAT1 locus of Histoplasma capsulatum were identified by PCR. A total of 28 fungal isolates, 6 isolates from human clinical samples and 22 isolates from environmental (infected bat and contaminated soil) samples, were studied. Among the 14 isolates from Mexico, 71.4% (95% confidence interval [95% CI], 48.3% to 94.5%) were of the MAT1-2 genotype, whereas 100% of the isolates from Brazil were of the MAT1-1 genotype. Each MAT1 idiomorphic region was sequenced and aligned, using the sequences of the G-217B (+ mating type) and G-186AR (- mating type) strains as references. BLASTn analyses of the MAT1-1 and MAT1-2 sequences studied correlated with their respective + and - mating type genotypes. Trees were generated by the maximum likelihood (ML) method to search for similarity among isolates of each MAT1 idiomorph. All MAT1-1 isolates originated from Brazilian bats formed a well-defined group; three isolates from Mexico, the G-217B strain, and a subgroup encompassing all soil-derived isolates and two clinical isolates from Brazil formed a second group; last, one isolate (EH-696P) from a migratory bat captured in Mexico formed a third group of the MAT1-1 genotype. The MAT1-2 idiomorph formed two groups, one of which included two H. capsulatum isolates from infected bats that were closely related to the G-186AR strain. The other group was formed by two human isolates and six isolates from infected bats. Concatenated ML trees, with internal transcribed spacer 1 (ITS1) -5.8S-ITS2 and MAT1-1 or MAT1-2 sequences, support the relatedness of MAT1-1 or MAT1-2 isolates. H. capsulatum mating types were associated with the geographical origin of the isolates, and all isolates from Brazil correlated with their environmental sources.