Molecular identification and phylogenetical analysis of dermatophyte fungi from Latin America

Dual RNA sequencing during Trichoderma harzianum-Phytophthora capsici interaction reveals multiple biological processes involved in the inhibition and highlights the cell wall as a potential target

BACKGROUND

Phytophthora capsici is a destructive oomycete pathogen, causing huge economic losses for agricultural production. The genus Trichoderma represents one of the most extensively researched categories of biocontrol agents, encompassing a diverse array of effective strains. The commercial biocontrol agent Trichoderma harzianum strain T-22 exhibits pronounced biocontrol effects against many plant pathogens, but its activity against P. capsici is not known.

RESULTS

T. harzianum T-22 significantly inhibited the growth of P. capsici mycelia and the culture filtrate of T-22 induced lysis of P. capsici zoospores. Electron microscopic analyses indicated that T-22 significantly modulated the ultrastructural composition of P. capsici, with a severe impact on the cell wall integrity. Dual RNA sequencing revealed multiple biological processes involved in the inhibition during the interaction between these two microorganisms. In particular, a marked upregulation of genes was identified in T. harzianum that are implicated in cell wall degradation or disruption. Concurrently, the presence of T. harzianum appeared to potentiate the susceptibility of P. capsici to cell wall biosynthesis inhibitors such as mandipropamid and dimethomorph. Further investigations showed that mandipropamid and dimethomorph could strongly inhibit the growth and development of P. capsici but had no impact on T. harzianum even at high concentrations, demonstrating the feasibility of combining T. harzianum and these cell wall synthesis inhibitors to combat P. capsici.

CONCLUSION

These findings provided enhanced insights into the biocontrol mechanisms against P. capsici with T. harzianum and evidenced compatibility between specific biological and chemical control strategies. © 2024 Society of Chemical Industry.

Epidemiologic features and therapeutic strategies of kerion: A nationwide multicentre study

BACKGROUND

Kerion is a severe type of tinea capitis that is difficult to treat and remains a public health problem.

OBJECTIVES

To evaluate the epidemiologic features and efficacy of different treatment schemes from real-world experience.

METHODS

From 2019 to 2021, 316 patients diagnosed with kerion at 32 tertiary Chinese hospitals were enrolled. We analysed the data of each patient, including clinical characteristics, causative pathogens, treatments and outcomes.

RESULTS

Preschool children were predominantly affected and were more likely to have zoophilic infection. The most common pathogen in China was Microsporum canis. Atopic dermatitis (AD), animal contact, endothrix infection and geophilic pathogens were linked with kerion occurrence. In terms of treatment, itraconazole was the most applied antifungal agent and reduced the time to mycological cure. A total of 22.5% of patients received systemic glucocorticoids simultaneously, which reduced the time to complete symptom relief. Furthermore, glucocorticoids combined with itraconazole had better treatment efficacy, with a higher rate and shorter time to achieving mycological cure.

CONCLUSIONS

Kerion often affects preschoolers and leads to serious sequelae, with AD, animal contact, and endothrix infection as potential risk factors. Glucocorticoids, especially those combined with itraconazole, had better treatment efficacy.

Sheep serve as a reservoir of Trichophyton mentagrophytes genotype V infection

Human infections by Trichophyton mentagrophytes occur mainly due to contact with diseased animals. In Iran, T. mentagrophytes genotype V is the most prevalent variant of the fungus. We aimed to determine the animal reservoir of T. mentagrophytes genotype V infection. The study was done on a total of 577 dermatophyte strains obtained from animals with signs of dermatophytosis and human patients. The list of extensively sampled animals included sheep, cows, cats and dogs. For human cases, epidemiological data were collected. All dermatophyte isolates from animals along with 70 human isolates morphologically similar to T. verrucosum and T. mentagrophytes genotype V were identified by rDNA internal transcribed spacer region restriction fragment length polymorphism analysis and DNA sequencing. A total of 334 animal dermatophyte strains were identified as Microsporum canis, T. mentagrophytes genotype V, T. verrucosum, Nannizzia gypsea, T. mentagrophytes genotype II*, T. mentagrophytes genotype VII, T. quinckeanum, and N. fulva. All clinical isolates identified as T. mentagrophytes genotype V originated from skin and scalp infections. Almost all veterinary isolates of T. mentagrophytes genotype V were cultured from sheep, but epidemiological data on animal-to-human transmission of T. mentagrophytes genotype V infection were limited and we found evidence in favor of interhuman transmission. In Iran, sheep maintain T. mentagrophytes genotype V population and therefore serve as animal reservoir of respective infections. The role of sheep as the source of human dermatophytosis due to T. mentagrophytes genotype V isolates is yet to be proven.

Comprehensive Taxonomical Analysis of Trichophyton mentagrophytes/interdigitale Complex of Human and Animal Origin from India

Taxonomic delineation of etiologic agents responsible for recalcitrant dermatophytosis causing an epidemic in India is still debated. The organism responsible for this epidemic is designated as T. indotineae, a clonal offshoot of T. mentagrophytes. To evaluate the real identity of the agent causing this epidemic, we performed a multigene sequence analysis of Trichophyton species isolated from human and animal origin. We included Trichophyton species isolated from 213 human and six animal hosts. Internal transcribed spacer (ITS) (n = 219), translational elongation factors (TEF 1-α) (n = 40), ß-tubulin (BT) (n = 40), large ribosomal subunit (LSU) (n = 34), calmodulin (CAL) (n = 29), high mobility group (HMG) transcription factor gene (n = 17) and α-box gene (n = 17) were sequenced. Our sequences were compared with Trichophyton mentagrophytes species complex sequences in the NCBI database. Except for one isolate (ITS genotype III) from animal origin, all the tested genes grouped our isolates and belonged to the "Indian ITS genotype", currently labeled as T. indotineae. ITS and TEF 1-α were more congruent compared to other genes. In this study, for the first time, we isolated the T mentagrophytes ITS Type VIII from animal origin, suggesting the role of zoonotic transmission in the ongoing epidemic. Isolation of T. mentagrophytes type III only from animal indicates its niche among animals. Outdated/inaccurate naming for these dermatophytes in the public database has created confusion in using appropriate species designation.

Aetiology of tinea capitis in China: A multicentre prospective study

BACKGROUND

Tinea capitis is still common in developing countries, such as China. Its pathogen spectrum varies across regions and changes over time.

OBJECTIVES

This study aimed to clarify the current epidemiological characteristics and pathogen spectrum of tinea capitis in China.

METHODS

A multicentre, prospective descriptive study involving 29 tertiary hospitals in China was conducted. From August 2019 to July 2020, 611 patients with tinea capitis were enrolled. Data concerning demography, risk factors and fungal tests were collected. The pathogens were further identified by morphology or molecular sequencing when necessary in the central laboratory.

RESULTS

Among all enrolled patients, 74.1% of the cases were 2- to 8-year-olds. The children with tinea capitis were mainly boys (56.2%) and more likely to have an animal contact history (57.4% vs. 35.3%, P = 0.012) and zoophilic dermatophyte infection (73.5%). The adults were mainly females (83.3%) and more likely to have anthropophilic agent infection (53.5%). The most common pathogen was zoophilic Microsporum canis (354, 65.2%), followed by anthropophilic Trichophyton violaceum (74, 13.6%). In contrast to the eastern, western and northeastern regions where zoophilic M. canis predominated, anthropophilic T. violaceum predominated in central China (69.2%, P < 0.0001), where the patients had the most tinea at other sites (20.3%) and dermatophytosis contact (25.9%) with the least animal contact (38.8%). Microsporum ferrugineum was the most common anthropophilic agent in the western area, especially in Xinjiang Province.

CONCLUSIONS

Boys aged approximately 5 years were mainly affected. Dermatologists are advised to pay more attention to the different transmission routes and pathogen spectra in different age groups from different regions.

New derivatives of the iridoid specioside from fungal biotransformation

Iridoids are widely found from species of Bignoniaceae family and exhibit several biological activities, such as anti-inflammatory, antimicrobial, antioxidant, and antitumor. Specioside is an iridoid found from Tabebuia species, mainly in Tabebuia aurea. Thus, here fungus-mediated biotransformation of the iridoid specioside was investigated by seven fungi. The fungus-mediated biotransformation reactions resulted in a total of nineteen different analogs by fungus Aspergillus niger, Aspergillus flavus, Aspergillus japonicus, Aspergillus terreus, Aspergillus niveus, Penicillium crustosum, and Thermoascus aurantiacus. Non-glycosylated specioside was the main metabolite observed. The other analogs were yielded from ester hydrolysis, hydroxylation, methylation, and hydrogenation reactions. The non-glycosylated specioside and coumaric acid were yielded by all fungi-mediated biotransformation. Thus, fungus applied in this study showed the ability to perform hydroxylation and glycosidic, as well as ester hydrolysis reactions from glycosylated iridoid. KEY POINTS: • The biotransformation of specioside by seven fungi yielded nineteen analogs. • The non-glycosylated specioside was the main analog obtained. • Ester hydrolysis, hydroxylation, methylation, and hydrogenation reactions were observe.

Molecular Identification and Antifungal Susceptibility Patterns of Dermatophytes Isolated from Companion Animals with Clinical Symptoms of Dermatophytosis

Introduction

Dermatophytosis is a common skin disease in cats and dogs caused by Microsporum and Trichophyton fungi. Species identification and knowledge of their antifungal susceptibility are therapeutically and epidemiologically important. This study assessed the prevalence of feline and canine dermatophytosis in Iran, identified the aetiological agents molecularly and tested their antifungal susceptibility.

Material and Methods

A total of 308 companion animals (134 dogs and 174 cats) with skin lesions were examined from March 2015 to March 2018. Hair and skin samples were examined by microscopy with 20% KOH and cultured on Sabouraud dextrose agar with cycloheximide and chloramphenicol. Fungal isolates were confirmed by sequencing of the internal transcribed spacer (ITS) r-DNA region. The antifungal susceptibility of dermatophytes was tested by broth microdilution assay using standard drugs.

Results

Dermatophytes were found in 130 (42.2%) samples, 62 of them feline and 68 canine. Based on sequencing of all strains, M. canis (78.5%, P<0.05), M. gypseum (10.7%), and T. mentagrophytes (10.7%) were the dermatophytes isolated. The non-dermatophyte species Nannizziopsis vriesii was also isolated from two feline dermatomycosis cases. Dogs and cats younger than one year (61.5%) showed a statistically significantly higher prevalence of infection (P<0.05). Caspofungin produced the lowest geometric mean MIC at 0.0018 μg/mL, followed by ketoconazole, terbinafine, itraconazole, miconazole, griseofulvin, clotrimazole and fluconazole, in a 0.038–1.53 μg/mL range.

Conclusion

This is the first molecular study to identify the causes of pet dermatophytosis in north-western Iran. ITS-PCR was shown to be a useful and reliable method for the identification of closely related species of dermatophytes in clinical and epidemiological settings. The lowest MIC of caspofungin indicated that this drug was the most potent in vitro.

Ex vivo potential of a quinoline-derivative nail lacquer as a new alternative for dermatophytic onychomycosis treatment

Introduction. Onychomycosis infections currently show a significant increase, affecting about 10 % of the world population. Trichophyton rubrum is the main agent responsible for about 80 % of the reported infections. The clinical cure for onychomycosis is extremely difficult and effective new antifungal therapy is needed.Hypothesis/Gap Statement. Ex vivo onychomycosis models using porcine hooves can be an excellent alternative for evaluating the efficacy of new anti-dermatophytic agents in a nail lacquer.Aim. Evaluation of the effectiveness of a nail lacquer containing a quinoline derivative on an ex vivo onychomycosis model using porcine hooves, as well as the proposal of a plausible antifungal mechanism of this derivative against dermatophytic strains.Methodology. The action mechanism of a quinoline derivative was evaluated through the sorbitol protection assay, exogenous ergosterol binding, and the determination of the dose-response curves by time-kill assay. Scanning electron microscopy evaluated the effect of the derivative in the fungal cells. The efficacy of a quinoline-derivative nail lacquer on an ex vivo onychomycosis model using porcine hooves was evaluated as well.Results. The quinoline derivative showed a time-dependent fungicidal effect, demonstrating reduction and damage in the morphology of dermatophytic hyphae. In addition, the ex vivo onychomycosis model was effective in the establishment of infection by T. rubrum.Conclusion. Treatment with the quinoline-derivative lacquer showed a significant inhibitory effect on T. rubrum strain in this infection model. Finally, the compound presents high potential for application in a formulation such as nail lacquer as a possible treatment for dermatophytic onychomycosis.

DNA topoisomerase 2 gene polymorphism in dermatophytes

BACKGROUND

Dermatophytes are a group of keratinophilic fungi of medical importance. Despite a relatively long history of molecular taxonomic studies, there is still a need for information on genetic polymorphism in wider variety of genomic loci.

OBJECTIVES

Our goal was to study partial DNA topoisomerase 2 gene (TOP2) polymorphism in dermatophytes.

METHODS

We performed DNA sequencing of TOP2 in 26 dermatophyte species along with ribosomal internal transcribed spacer (ITS) sequencing.

RESULTS

The number of polymorphic sites in TOP2 data set was similar to that one in ITS data set. Nannizzia species formed paraphyletic group in TOP2 tree. Trichophyton simii was paraphyletic in concatenated TOP2-ITS tree, one of its two clades contained solely Iranian isolates.

CONCLUSIONS

Our results revealed several unresolved problems in the taxonomy of dermatophytes, including probable polyphyly of the genus Nannizzia and the species T simii.

Trichophyton mentagrophytes and T interdigitale genotypes are associated with particular geographic areas and clinical manifestations

The fungi Trichophyton mentagrophytes and T interdigitale account for significant amount of dermatophytosis cases worldwide. These two dermatophytes form a species complex and have a number of ribosomal internal transcribed spacer (ITS) region genotypes, allowing simultaneous species identification and strain typing. Our aim was to describe the geographic distribution of T mentagrophytes/T interdigitale ITS region genotypes and find an association between the genotypes and clinical presentations of respective infections. We performed rDNA ITS region sequencing in 397 Iranian T mentagrophytes/T interdigitale isolates and analysed all available in GenBank entries with sequences of this kind. For the study, 515 clinical annotations were available. Statistical analysis was performed by chi-squared test and Spearman rank correlation analysis. A total of 971 sequences belonged to genotypes with at least 10 geographic annotations and were classified on the basis of exclusive occurrence in a particular region or high relative contribution to a regional sample. We discerned Asian and Oceanian ("KU496915" Type V, "KT192500" Type VIII, "KU315316"), European ("FM986750" Type III, "MF926358" Type III*, "KT285210" Type VI) and cosmopolitan ("FM986691" Type I, "JX122216" Type II, "KP132819" Type II* and "AF170453" Type XXIV) genotypes. There was statistically significant difference in the ITS genotype distribution between different affected body sites. Trichophyton mentagrophytes "KT192500" Type VIII correlated with tinea cruris, T mentagrophytes "KU496915" Type V correlated with tinea corporis, T interdigitale "JX122216" Type II correlated with tinea pedis and onychomycosis. Trichophyton mentagrophytes and T interdigitale genotypes can be associated with distinct geographic locations and particular clinical presentations.

Mycoses in northeastern Brazil: epidemiology and prevalence of fungal species in 8 years of retrospective analysis in Alagoas

Superficial and cutaneous mycoses are common in tropical countries, caused by dermatophytes, yeast, and non-dermatophyte molds in different clinical specimens. In order to define the epidemiology of mycoses and the profile of their etiological agents in Alagoas (northeastern Brazil) between 2009 and 2016, we obtained data of patients from the main laboratories of Alagoas, by examining clinical samples with direct microscopy and culture on Sabouraud dextrose agar and Chromagar^®Candida. A total of 3316 patients were confirmed with mycoses (595 men/2716 women) and 40.25 of average age. Positive samples totaled 3776, mainly vaginal secretion (1593/42.2%), toenails (876/23.2%), and fingernails (589/15.6%). Yeasts were the most isolated (3129/82.9%), including 3012 Candida spp. (79.8%), 57 Malassezia spp. (1.5%), 42 Trichosporon sp. (1.1%), 10 Geotrichum spp. (0.3%), and 8 Rhodotorula spp. (0.2%). Candida albicans was the most frequent species (715/18.9%), followed by C. krusei (194/5.1%), C. tropicalis (24/0.6%), and 2079 unspecified species (55.1%). Among 17.1% filamentous fungi, 14.8% dermatophytes were distributed as 211 Trichophyton sp. (5.6%), 125 T. rubrum (3.3%), 106 T. tonsurans (2.8%), 72 T. mentagrophytes (1.9%), 2 Microsporum sp. (0.1%), 15 M. canis (0.4%), and 26 Epidermophyton sp. (0.7%). Other fungi represented the minority: Fusarium sp. and Aspergillus sp. These are the first clinical data on the Alagoas population affected by fungi pathogens, confirming a higher incidence of candidiasis (mainly vulvovaginal and onychomycosis) and dermatophytes, providing a better understanding of different mycoses in northeastern Brazil.

Species boundaries in the Trichophyton mentagrophytes / T. interdigitale species complex

The fungi Trichophyton mentagrophytes and T. interdigitale are closely related species, causing superficial infections in humans and other mammals. The status of these taxa is a field of long-lasting debates. To clarify their phylogenetic relationships within the genus Trichophyton and sharpen the species boundaries, we performed sequencing of four T. mentagrophytes genomes and also evaluated three previously published multilocus data sets. We performed computational species delimitation analysis on all available in GenBank internal transcribed spacer region (ITS) sequences of Trichophyton spp. Phylogenomic data, phylogenetic network, and species delimitation analyses implied that T. mentagrophytes and T. interdigitale belong to the same phylogenetic species. However, we argue that taxonomic status quo should be retained, from the perspective of epidemiological data and the principle of taxonomic stability. Since there is a correlation between ITS genotype and epidemiological source of an isolate, restriction of T. interdigitale to purely anthropophilic ITS genotypes seems to be reasonable.

PRP8 intein in dermatophytes: Evolution and species identification

Dermatophytes are keratinophilic fungi belonging to the family Arthrodermataceae. Despite having a monophyletic origin, its systematics has always been complex and controversial. Sequencing of nuclear ribosomal ITS and D1/D2 rDNA has been proposed as an efficient tool for identifying species in this group of fungi, while multilocus analyses have been used for phylogenetic species recognition. However, the search for new markers, with sequence and size variation, which enable species identification in only one polymerase chain reaction (PCR) step, is very attractive. Inteins seems to fulfill these characteristics. They are self-splicing genetic elements present within housekeeping coding genes, such as PRP8, that codify the most important protein of the spliceosome. The PRP8 intein has been described for Microsporum canis in databases but has not been studied in dermatophytes in any other published work. Thus, our aim was to determine the potential of this intervening element for establishing phylogenetic relationships among dermatophytes and for identifying species. It was found that all studied species have a full-length PRP8 intein with a Homing Endonuclease belonging to the family LAGLIDADG. Phylogenetic analyses were consistent with other previous phylogenies, confirming Epidermophyton floccosum in the same clade of the Arthroderma gypseum complex, Microsporum audouinii close to M. canis, differentiating A. gypseum from Arthroderma incurvatum, and in addition, better defining the Trichophyton interdigitale and Trichophyton rubrum species grouping. Length polymorphism in the HE region enables identification of the most relevant Microsporum species by a simple PCR-electrophoresis assay. Intein PRP8 within dermatophytes is a powerful additional tool for identifying and systematizing dermatophytes.

Molecular identification and phylogenetic analysis of Bothrops insularis bacterial and fungal microbiota

Bothrops insularis, known as the golden lancehead snake, has its natural habitat restricted to Queimada Grande Island on the southern coast of Brazil. This culture-dependent study aimed to identify microorganisms obtained from the mouth, eyes, and cloaca of this species. Swabs from 20 snakes were collected for fungal and bacterial isolation. DNA was extracted from all samples, and identification was performed by amplifying the ITS1-5.8S-ITS2 regions and the 16S rDNA gene, respectively. All strains were identified and deposited in the GenBank nucleotide database. MEGA v6.0 software was utilized to construct phylogenetic trees. In total, 100 strains were isolated and characterized, from which 42 fungi were distributed into 23 species and 58 bacteria into 13 species. The genus Fusarium was predominant since 11 strains and probably a new species was isolated from this fungus. Pseudomonas aeruginosa and Enterococcus faecalis were the predominant groups of aerobic bacteria isolated. Phylogenetic analyses between bacterial and fungal sequences suggest a similarity between the microorganisms found on the island and on the continent. These findings may be attributed to anthropic actions resulting from both expeditions to the island and actions of migratory birds, which are the main sources of food for snakes.

Distribution of Species of Dermatophyte Among Patients at a Dermatology Centre of Nghean Province, Vietnam, 2015-2016

INTRODUCTION

Vietnam is a tropical country so fungal diseases including dermatophytosis may be prevalent, but epidemiological profiles of agents responsible for the infection have rarely been reported.

OBJECTIVE

To find out the distribution of dermatophytes among patients living in a central province of Vietnam.

METHODS

We examined dermatophyte infections in patients with lesions suspected of dermatophytosis referred to the Nghean provincial leprosy and dermatology centre from August 2015 to August 2016. The speciation of dermatophyte was performed by conventional and molecular approaches.

RESULTS

One hundred and thirty-six patients (90 males and 46 females) were included. Those aged from 11 to 30 contribute 59.1%. The most common agent found was Trichophyton rubrum (66.9%), followed by T. interdigitale (12.5%), T. tonsurans (9.6%), Microsporum incurvatum (8.1%), and the less frequent species were M. canis (2.2%) and T. violaceum (0.7%). Epidermophyton floccosum was not reported. T. rubrum were more common in men (74.4%) than in women (52.2%), while T. interdigitale and M. incurvatum were more common in women (21.7 and 15.2%) than in men (7.8 and 4.4%). Patients infected with Microsporum spp. had small-sized lesions for only 3 months, while those affected by Trichophyton spp. had large-sized lesions with longer duration.

CONCLUSION

Trichophyton species are the predominant agents of infection in Nghean province, while Epidermophyton species is absent. Additional investigations are required to clarify the epidemiological profile of dermatophytes in Vietnam.