A severe outbreak of highly virulent and multi-resistant dermatophytosis by species in the
Trichophyton mentagrophytes
/
T
.
interdigitale
complex is ongoing in India. The correct identity of the ...etiologic agent is a much-debated issue. In order to define species limits, a taxonomic study was undertaken combining molecular, morphological, and physiological characteristics as evidence of classification. Molecular characteristics show that
T. mentagrophytes s. str
. and
T. interdigitale s. str
. can be distinguished with difficulty from each other, but are unambiguously different from the Indian genotype,
T
.
indotineae
by sequences of the HMG gene. The entities were confirmed by multilocus analysis using tanglegrams. Phenotypic characters of morphology and physiology are not diagnostic, but statistically significant differences are observed between the molecular siblings. These properties may be drivers of separate evolutionary trends.
Trichophyton mentagrophytes
represents the ancestral, homothallic cloud of genotypes with a probable geophilic lifestyle, while
T
.
indotineae
and
T
.
interdigitale
behave as anthropophilic, clonal offshoots. The origin of
T
.
indotineae
, which currently causes a significant public health problem, is zoonotic, and its emergence is likely due to widespread misuse of antifungals.
Trichophyton (T.) indotineae is a newly identified dermatophyte species that has been found in a near-epidemic form on the Indian subcontinent. There is evidence of its spread from the Indian ...subcontinent to a number of countries worldwide. The fungus is identical to genotype VIII within the T. mentagrophytes/T. interdigitale species complex, which was described in 2019 by sequencing the Internal Transcribed Spacer (ITS) region of ribosomal DNA of the dermatophyte. More than 10 ITS genotypes of T. interdigitale and T. mentagrophytes can now be identified. T. indotineae causes inflammatory and itchy, often widespread, dermatophytosis affecting the groins, gluteal region, trunk, and face. Patients of all ages and genders are affected. The new species has largely displaced other previously prevalent dermatophytes on the Indian subcontinent. T. indotineae has become a problematic dermatophyte due to its predominantly in vitro genetic resistance to terbinafine owing to point mutations of the squalene epoxidase gene. It also displays in vivo resistance to terbinafine. The most efficacious drug currently available for this terbinafine-resistant dermatophytoses, based on sound evidence, is itraconazole.
Background
An alarming increase in recalcitrant dermatophytosis has been witnessed in India over the past decade. Drug resistance may play a major role in this scenario.
Objectives
The aim of the ...present study was to determine the prevalence of in vitro resistance to terbinafine, itraconazole and voriconazole in dermatophytes, and to identify underlying mutations in the fungal squalene epoxidase (SQLE) gene.
Patients/Methods
We analysed skin samples from 402 patients originating from eight locations in India. Fungi were identified by microbiological and molecular methods, tested for antifungal susceptibility (terbinafine, itraconazole, voriconazole), and investigated for missense mutations in SQLE.
Results
Trichophyton (T.) mentagrophytes internal transcribed spacer (ITS) Type VIII was found in 314 (78%) samples. Eighteen (5%) samples harboured species identified up to the T interdigitale/mentagrophytes complex, and T rubrum was detected in 19 (5%) samples. 71% of isolates were resistant to terbinafine. The amino acid substitution Phe397Leu in the squalene epoxidase of resistant T mentagrophytes was highly prevalent (91%). Two novel substitutions in resistant Trichophyton strains, Ser395Pro and Ser443Pro, were discovered. The substitution Ala448Thr was found in terbinafine‐sensitive and terbinafine‐resistant isolates but was associated with increased MICs of itraconazole and voriconazole.
Conclusions
The high frequencies of terbinafine resistance in dermatophytes are worrisome and demand monitoring and further research. Squalene epoxidase substitutions between Leu393 and Ser443 could serve as markers of resistance in the future.
•A Somalian woman presented with a Biatriospora mackinnonii infection.•A triad of tumors, fistula, and secreted granules is diagnostically characteristic.•Eumycetoma is one of the World Health ...Organizations's “neglected tropical diseases”.•Therapy with azoles should be given for at least 12 to 36 months.•If left untreated Eumycetoma might result in loss of function of the extremities or amputation.
Species of the
Trichophyton benhamiae
complex are predominantly zoophilic pathogens with a worldwide distribution. These pathogens have recently become important due to their epidemic spread in pets ...and pet owners. Considerable genetic and phenotypic variability has been revealed in these emerging pathogens, but the species limits and host spectra have not been clearly elucidated. In this study, we used an approach combining phylogenetic analysis based on four loci, population-genetic data, phenotypic and physiological analysis, mating type gene characterization and ecological data to resolve the taxonomy of these pathogens. This approach supported the inclusion of nine taxa in the complex, including three new species and one new variety.
Trichophyton benhamiae
var.
luteum
var. nov. (“yellow phenotype” strains) is currently a major cause of zoonotic tinea corporis and capitis in Europe (mostly transmitted from guinea pigs). The isolates of the “white phenotype” do not form a monophyletic group and are segregated into three taxa,
T. benhamiae
var.
benhamiae
(mostly North America; dogs),
T. europaeum
sp. nov. (mostly Europe; guinea pigs), and
T. japonicum
sp. nov. (predominant in East Asia but also found in Europe; rabbits and guinea pigs). The new species
T. africanum
sp. nov. is proposed for the “African” race of
T. benhamiae
. The introduction to new geographic areas and host jump followed by extinction of one mating type gene have played important roles in the evolution of these pathogens. Due to considerable phenotypic similarity of many dermatophytes and phenomena such as incomplete lineage sorting or occasional hybridization and introgression, we demonstrate the need to follow polyphasic approach in species delimitation. Neutrally evolving and noncoding DNA regions showed significantly higher discriminatory power compared to conventional protein-coding loci. Diagnostic options for species identification in practice based on molecular markers, phenotype and MALDI-TOF spectra are presented. A microsatellite typing scheme developed in this study is a powerful tool for the epidemiological surveillance of these emerging pathogens.
Summary
Background
The Indian ITS genotype VIII Trichophyton mentagrophytes population shows a high amount of different erg1 (ergosterol) mutants encoding for squalene epoxidase, which catalyses the ...first step of ergosterol biosynthesis.
Objectives
Illumination of the implication of point mutations at position Ala448Thr in single and double erg1 T mentagrophytes mutants because mutants of this type were abundantly found within the Indian fungal population.
Methods
Growth in fluconazole or terbinafine containing medium was analysed using a microplate‐laser‐nephelometry (MLN)‐based growth assay.
Results
Ala 448 Thr erg1 single mutants were terbinafine sensitive, but about 50% of isolates showed an increased fluconazole resistance, whereas 95% of the double mutants (Phe 397 Leu, Ala 448Thr) demonstrated combined terbinafine and increased fluconazole resistance.
Conclusion
The new Indian T mentagrophytes populations show several point mutations in erg1. Point mutations at position 397 were previously described and cause terbinafine resistance. A large part of the double mutants exhibit resistance to terbinafine and fluconazole, demonstrating a selective advantage of the combination of both mutations.
Altogether 285 dermatophyte isolates of 21 different species - including both Trichophyton rubrum and T. interdigitale, but also eight additional Trichophyton species, Microsporum canis and seven ...other Microsporum species, as well as Epidermophyton floccosum and Arthroderma spp. - were analyzed using Matrix Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) and the AnagnosTec 'SARAMIS' (Spectral Archiving and Microbial Identification System) software. In addition, sequence analysis of the internal transcribed spacer (ITS) of the ribosomal DNA was performed for a high number of the tested strains. Sufficient agreement was found between the results obtained with standard identification methods and those with the MALDI-TOF MS for species identification of dermatophytes. A mass spectra database was constructed which contained the species identifications of all 285 isolates. The results were confirmed for 164 of the isolates by sequence analysis of the internal transcribed spacer (ITS) of the ribosomal DNA. Statistical analysis of all 285 dermatophyte strains showed that conventional identification matched the results of MALDI-TOF MS for 78.2% of the isolates tested. In the case of the 164 isolates for which the identifications were confirmed by PCR, the results of their conventional diagnosis and MALDI-TOF MS were in agreement for only 68.9 % (113 of 164 strains) of the test isolates. In contrast, there was agreement of 99.3 % or 98.8 % in the identifications obtained with PCR and MALDI-TOF MS techniques (283/285 or 162/164). The two exceptions were isolates that proved to be T. violaceum which could not be identified by the MALDI-TOF MS technique. In conclusion, the MALDI-TOF mass spectroscopy represents a fast and very specific method for species differentiation of dermatophytes grown in culture.
Ciclopirox 8% hydroxypropyl chitosan (HPCH) Marketed in different countries as the following registered (®) brands: Ciclopoli, Fulcare, Kitonail, Myconail, Niogermos, Niogermox, Onytec, Ony-Tec, ...Polinail, Privex, Rejuvenail is the first topical nail lacquer developed using innovative drug formulation technology. It is indicated for the treatment of mild-to-moderate fungal infections of the nails that are caused by dermatophytes and/or other ciclopirox-sensitive fungi, without nail matrix involvement. HPCH is a patented drug formulation technology for the delivery of active principles into the nails based on a hydrosoluble semisynthetic amino-polysaccharide biopolymer derivative of chitosan. The lacquer acts as a protective barrier against microbiological attack, physical damage and/or aggressive chemicals. Results from in vitro studies suggest that the application of ciclopirox 8% HPCH nail lacquer improves drug permeation into and/or drug penetration through the nail, relative to the water-insoluble ciclopirox 8%, amorolfine 5% and efinaconazole 10% reference lacquers. In addition, in vitro and clinical studies in healthy subjects found that the concentration of ciclopirox reached in subungual fluids after application of ciclopirox 8% HPCH was sufficient for inhibiting fungal growth. In clinical studies in patients with mild-to-moderate onychomycosis, ciclopirox 8% HPCH was found to be more effective than the commercial water-insoluble ciclopirox 8% and amorolfine 5% lacquers, as indicated by higher complete cure, response and mycological cure rates at 48 weeks after treatment initiation. Ciclopirox 8% HPCH has been found to be generally well tolerated, with no treatment-related adverse events reported in patients using this nail lacquer. Thus, current evidence indicates that ciclopirox 8% HPCH represents a valuable treatment option for the treatment of patients with onychomycosis.
Chronic recalcitrant dermatophytoses, due to Trichophyton (T.) mentagrophytes Type VIII are on the rise in India and are noteworthy for their predominance. It would not be wrong to assume that travel ...and migration would be responsible for the spread of T. mentagrophytes Type VIII from India, with many strains resistant to terbinafine, to other parts of the world. From September 2016 until March 2020, a total of 29 strains of T. mentagrophytes Type VIII (India) were isolated. All patients were residents of Germany: 12 females, 15 males and the gender of the remaining two was not assignable. Patients originated from India (11), Pakistan (two), Bangladesh (one), Iraq (two), Bahrain (one), Libya (one) and other unspecified countries (10). At least two patients were German-born residents. Most samples (21) were collected in 2019 and 2020. All 29 T. mentagrophytes isolates were sequenced (internal transcribed spacer (ITS) and translation elongation factor 1-α gene (TEF1-α)). All were identified as genotype VIII (India) of T. mentagrophytes. In vitro resistance testing revealed 13/29 strains (45%) to be terbinafine-resistant with minimum inhibitory concentration (MIC) breakpoints ≥0.2 µg/mL. The remaining 16 strains (55%) were terbinafine-sensitive. Point mutation analysis revealed that 10/13 resistant strains exhibited Phe397Leu amino acid substitution of squalene epoxidase (SQLE), indicative for in vitro resistance to terbinafine. Two resistant strains showed combined Phe397Leu and Ala448Thr amino acid substitutions, and one strain a single Leu393Phe amino acid substitution. Out of 16 terbinafine-sensitive strains, in eight Ala448Thr, and in one Ala448Thr +, new Val444 Ile amino acid substitutions were detected. Resistance to both itraconazole and voriconazole was observed in three out of 13 analyzed strains. Treatment included topical ciclopirox olamine plus topical miconazole or sertaconazole. Oral itraconazole 200 mg twice daily for four to eight weeks was found to be adequate. Terbinafine-resistant T. mentagrophytes Type VIII are being increasingly isolated. In Germany, transmission of T. mentagrophytes Type VIII from the Indian subcontinent to Europe should be viewed as a significant public health issue.
Dermatophytoses represent a major health burden in animals and man. Zoophilic dermatophytes usually show a high specificity to their original animal host but a zoonotic transmission is increasingly ...recorded. In humans, these infections elicit highly inflammatory skin lesions requiring prolonged therapy even in the immunocompetent patient. The correct identification of the causative agent is often crucial to initiate a targeted and effective therapy. To that end, matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) represents a promising tool. The objective of this study was to evaluate the reliability of species identification of zoophilic dermatophytes using MALDI-TOF MS. The investigation of isolates from veterinary clinical samples suspicious of dermatophytoses suggests a good MALDI-TOF MS based identification of the most common zoophilic dermatophyte
spp. usually achieved scores only around the cutoff value for secure species identification because of a small number of reference spectra. Moreover, these results need to be interpreted with caution due to the close taxonomic relationship of dermatophytes being reflected in very similar spectra. In our study, the analysis of 50 clinical samples of hedgehogs revealed no correct identification using the provided databases, nor for zoophilic neither for geophilic causative agents. After DNA sequencing, adaptation of sample processing and an individual extension of the in-house database, acceptable identification scores were achieved (
and
spp., respectively). A score-oriented distance dendrogram revealed clustering of geophilic isolates of four different species of the genus
and underlined the close relationship of the important zoophilic agents
and
by forming a subclade within a larger cluster including different dermatophytes. Taken together, MALDI-TOF MS proofed suitable for the identification of zoophilic dermatophytes provided fresh cultures are used and the reference library was previously extended with spectra of laboratory-relevant species. Performing independent molecular methods, such as sequencing, is strongly recommended to substantiate the findings from morphologic and MALDI-TOF MS analyses, especially for uncommon causative agents.
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