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.

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. 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. 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.

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 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.

Background: Tinea capitis remains one of the most common superficial fungal infections in children worldwide and represents an important public health concern due to its high prevalence, potential complications, and changing epidemiology. This study aimed to characterize the epidemiological trends and etiological distribution of tinea capitis across the Americas through a systematic review of the available literature. Methods: A systematic search was conducted in MEDLINE (PubMed), Scopus, SCILIT, and SciELO following PRISMA guidelines. A total of 250 records were identified, of which 75 duplicates were removed. After title and abstract screening and eligibility assessment, 90 studies were included. Observational studies, prevalence studies, case series, and case reports reporting epidemiological or etiological data on tinea capitis in countries of the American continent were considered eligible. Methodological quality was assessed using the Joanna Briggs Institute (JBI) critical appraisal tools. No formal certainty-of-evidence assessment or meta-analysis was performed due to the descriptive nature and heterogeneity of the included studies. This review was not prospectively registered. Results: The 90 included studies comprised 506,086 reported cases of tinea capitis. Marked regional differences were identified in the distribution of dermatophyte species. Trichophyton tonsurans predominated in North America and several Caribbean countries, whereas Microsporum canis was the most frequently reported etiological agent in much of South America and parts of Central America, suggesting an important role of zoonotic transmission in these regions. Variations in prevalence and species distribution were also associated with geographic, socioeconomic, and demographic factors. Overall, the included studies demonstrated low-to-moderate methodological risk of bias. Conclusions: These findings demonstrate substantial heterogeneity in the epidemiology of tinea capitis throughout the Americas and highlight the importance of continuous surveillance, accurate mycological diagnosis, and region-specific public health strategies to improve disease control and guide appropriate therapeutic interventions.