Search Results (26)

Toenail onychomycosis causes significant problems in public health and is more common among the elderly and immune-compromised populations. A previous culture-based survey of communal finely ground toenails from the east coast of Australia isolated 125 T. interdigitale but only one T. rubrum. This paucity of T. rubrum was surprising because it is one of the most common dermatophytes isolated worldwide. Our aim was to find out if T. rubrum was present but not cultured. DNA was extracted from ground toenails from the same samples. New specific primers were designed for the ITS region of T. rubrum that excluded T. interdigitale and vice versa. PCR with these new primers found T. rubrum as well as T. interdigitale in all ground toenail samples. This suggests that T. rubrum was present and common in the ground toenails. It was possibly missed by culture because it grows slowly and was overgrown by T. interdigitale and non-dermatophyte moulds. Alternatively, its viability may have declined earlier, during collection, treatment, or storage of the ground toenails. This has implications for studies of clinical materials, especially nails, as infection by T. rubrum (the most common dermatophyte) may be missed by culture, the main method used in pathology laboratories. Full article

Background: Trichophyton indotineae, a new emerging pathogen according to the WHO, is known to cause severe forms of tinea. Given that traditional identification methods rely on morphological characteristics, and the morphological distinctions among T. indotineae, T. mentagrophytes, and T. interdigitale are minimal, the adoption of alternative diagnostic techniques, such as RT-PCR or gene sequencing, has become critically important to prevent misidentification. The purpose of this study was firstly to analyze the local epidemiology of dermatophytes isolated and secondly to investigate the presence of T. indotineae among the isolated strains. Methods: Between January 2021 and June 2024, 1096 samples of skin adnexa were analysed. The isolated strains belonging to the genus Trichophyton were submitted to molecular identification by ITS sequencing, and T. indotineae strains were subjected to squalene epoxidase (SQLE) sequencing analysis. Results: Trichophyton rubrum and Trichophyton interdigitale appear to be the most prevalent pathogenic species. Molecular identification reveals four T. indotineae strains (4/87; 4.61%) from Asian patients, which were also characterized by gene mutations associated with terbinafine resistance. Conclusions: This study has made it clear that there is a need to implement basic mycological diagnostics with molecular methods to avoid misidentifications, ensure the correct identification, and evaluate the presence of mutations associated with antifungal drug resistance. Full article

The identification of filamentous fungi by matrix-assisted laser desorption/ionization–time of flight mass spectrometry (MALDI–TOF MS) represents a challenge due to their complex taxonomy and the lack of comprehensive databases. The aim of this study was to evaluate the current status of available MALDI–TOF MS databases for the identification of dermatophytes, including commercial, in-house, and web-based databases. We collected 289 dermatophyte strains from different centers and analyzed them using four databases and a combination of them. The combination of commercial and in-house databases was shown to improve the identification rate and accuracy at the species level. For Trichophyton rubrum, the concordance among all databases was above 90.0%. For the T. mentagrophytes group, correct identification at the species level ranged from 30.0 to 78.9%, depending on the database, and showed very low agreement among them. The addition of the novel species T. japonicum to our in-house database resulted in the successful identification of this species. On the other hand, T. interdigitale and T. tonsurans were the species most frequently misidentified by MALDI–TOF MS. Through deep spectra analysis of both species, up to 29 protein peaks were found to be suitable for their differentiation, demonstrating the potential of peak analysis in differentiating closely related species. In conclusion, improvements of the databases with new strains resulted in increased identification accuracy at the species level. This, combined with peak analysis, could improve the overall identification of dermatophytes by MALDI–TOF MS in clinical laboratories. Full article

Cutaneous fungal infections represent a significant burden worldwide with a high impact on public health. Accurate identification of dermatophyte species causing these infections is vital for an appropriate treatment. Terbinafine is the primary agent against Trichophyton species due to its clinical efficacy; however, cases of elevated minimum inhibitory concentration (MIC) have been reported, raising clinical and epidemiological concerns. Herein, we aimed to detect Trichophyton rubrum and Trichophyton interdigitale isolates collected from clinical samples with terbinafine-high MICs (TRB-hMIC). A total of 168 isolates, recovered from 2017 to 2023, were identified as T. rubrum complex (140/83.4%) or T. interdigitale (28/16.7%) and further screened regarding their terbinafine susceptibility. Four isolates with capacity to grow in terbinafine media were detected by screening, and these and a further sixteen random isolates were submitted to the broth microdilution method. This methodology confirmed the four (2.4%) isolates as TRB-hMIC. One T. rubrum and three T. interdigitale showed a minimum inhibitory concentration (MIC) higher than 1 mg/L. Partial sequencing of the SQLE gene identified point mutations in T. rubrum (Phe397Iso) and in one T. interdigitale (Phe397Leu) isolate. Notably, in the other two T. interdigitale isolates with TRB-hMIC, no point mutations in the SQLE gene were identified. In conclusion, TRB-hMIC isolates (T. rubrum and T. interdigitale) were identified in clinical samples analyzed in Portugal, as antifungal susceptibility testing is a crucial routine for identifying treatment failures and also for epidemiological purposes aiming to monitor the dynamics of terbinafine resistance. Full article

Trichophyton (T.) mentagrophytes ITS genotype VIII, also known as Trichophyton indotineae, is a new species of the T. mentagrophytes/T. interdigitale complex and its first records, albeit under a different species name, are from the Indian subcontinent, Middle Eastern Asia, and West Asia. T. mentagrophytes genotype VIII (T. indotineae) has spread globally and has now been documented in over 30 countries. The aim of this study was to investigate the occurrence and proportion of terbinafine- and itraconazole-resistant isolates of T. mentagrophytes ITS genotype VIII (T. indotineae) in Bangladesh. This was part of an official collaborative project between IADVL (Indian Association of Dermatologists, Venereologists, and Leprologists) and Bangabandhu Sheikh Mujib Medical University (BSMMU), Bangladesh. Over a period of 6 months, ninety-nine patients of chronic recalcitrant tinea corporis were recruited from BSMMU hospital. Species identification was performed by fungal culture and morphological observation of the upper and lower surfaces of fungal colonies, as well as by using fluorescent microscopy. In addition, a PCR (polymerase chain reaction)-ELISA was performed to group the patients into those with the T. mentagrophytes/T. interdigitale complex. The internal transcribed spacer (ITS) gene was sequenced. Samples were tested for resistance to terbinafine and itraconazole by mutational analyses of the squalene epoxidase (SQLE) and the ergosterol 11B (ERG11B) genes. A total of 79/99 samples showed a positive culture. In 76 of these isolates, T. mentagrophytes ITS genotype VIII (T. indotineae) could be reliably identified both by culture and molecular testing. Resistance testing revealed terbinafine resistance in 49 and itraconazole resistance in 21 patients. Among these, 11 patients were resistant to both the antifungal agents. Mutations L393S, L393F, F397L, and F397I of the SQLE gene were associated with terbinafine resistance. Resistance to itraconazole could not be explained by mutations in the ERG11B gene. Infections with T. mentagrophytes ITS genotype VIII (T. indotineae) have become a public health issue with potentially global ramifications. About 62% of samples from Bangladesh showed resistance to terbinafine, making oral itraconazole the most effective drug currently available, although resistance to itraconazole and both terbinafine and itraconazole also exists. Full article

Background: In recent decades, globalization and international migration have increased the spread of infectious agents, including dermatophytes. Although considered minor infections, dermatophytoses are highly contagious, and they significantly reduce the quality of life, inducing itching, burning, sleep disturbances, and even depressive states. Moreover, the increasing resistance to antifungals threats the public health and burdens the costs for the healthcare system. Methods: DermaGenius^® Resistance Multiplex real-time PCR assay allowed to analyze the terbinafine susceptibility/resistance of 172 Trichophyton strains, which were isolated from human and animal samples collected from 2016 to May 2024 and previously identified by Sanger sequencing. Results: All the 11 animal strains belonged to the T. interdigitale/T. mentagrophytes complex and tested terbinafine sensitive. Out of 161 human strains, 9 (5.6%) showed terbinafine resistance and 7 (4.3%) were identified as T. indotineae. Conclusions: This study provides preliminary data about behavior toward antifungals in animals and finalizes the scientific information currently available about human strains, highlighting the importance of the One Health concept. Moreover, it supports the relevant role of T. indotineae as an emerging dermatophyte with high proportion of terbinafine resistance. Full article

Trichophyton indotineae is an emerging dermatophyte species that plays a relevant role in human healthcare. It has been associated with severe chronic skin infections and a high level of terbinafine resistance. T. indotineae is endemic to India, Iran, and Iraq but several cases have been reported in Europe, recently. In this manuscript, the authors report the first clinical description of a tinea corporis and onychomycosis due to T. indotineae. The patient was a 42-year-old female from India that has lived in Umbria (Central Italy) for the last two years. Firstly, a dermatological examination suggested dermatophytosis: mycology isolation from cultures and macro- and microscopical features identified the colonies as belonging to the T. mentagrophytes/T. interdigitale species complex. Subsequently, ITS1/ITS4 end-point PCR and Sanger sequencing identified the strain as T. indotineae. Lastly, a DermaGenius^® Resistance Multiplex real-time PCR assay was carried out, targeting the mutations in the SQLE gene to establish terbinafine resistance or susceptibility of the strain. The melting curve observed was compatible with wild-type positive control, identifying the strain as T. indotineae terbinafine-sensitive. An oral terbinafine treatment was associated with a topical ciclopirox nail solution, resulting in remission in its clinical manifestation. On 3 July 2023, the local Prevention Service notified the case to the Ministry of Health that then reported the information at national and international levels. Full article

Several prolonged and significant outbreaks of dermatophytosis caused by Trichophyton indotineae, a new emerging terbinafine-resistant species, have been ongoing in India in recent years, and have since spread to various countries outside Asia. Miltefosine, an alkylphosphocholine, is the most recently approved drug for the treatment of both visceral and cutaneous leishmaniasis. Miltefosine in vitro activity against terbinafine-resistant and susceptible T. mentagrophytes/T. interdigitale species complex, including T. indotineae, is limited. The current study aimed to assess miltefosine’s in vitro activity against dermatophyte isolates, which are the most common causes of dermatophytosis. Miltefosine, terbinafine, butenafine, tolnaftate, and itraconazole susceptibility testing was performed using Clinical and Laboratory Standards Institute broth microdilution methods (CLSI M38-A3) against 40 terbinafine-resistant T. indotineae isolates and 40 terbinafine-susceptible T. mentagrophytes/T. interdigitale species complex isolates. Miltefosine had MIC ranges of 0.063–0.5 µg/mL and 0.125–0.25 µg/mL against both terbinafine-resistant and susceptible isolates. In terbinafine-resistant isolates, the MIC₅₀ and MIC₉₀ were 0.125 µg/mL and 0.25 µg/mL, respectively, and 0.25 µg/mL in susceptible isolates. Miltefosine had statistically significant differences in MIC results when compared to other antifungal agents (p-value 0.05) in terbinafine-resistant strains. Accordingly, the findings suggest that miltefosine has a potential activity for treating infections caused by terbinafine-resistant T. indotineae. However, further studies are needed to determine how well this in vitro activity translates into in vivo efficacy. Full article

Dermatophytes are fungi included in the genera Trichophyton, Microsporum, Epidermophyton, Nannizzia, Paraphyton, Lophophyton, and Arthroderma. Molecular techniques have contributed to faster and more precise identification, allowing significant advances in phylogenetic studies. This work aimed to identify clinical isolates of dermatophytes through phenotypic (macro- and micromorphology and conidia size) and genotypic methods (sequences of ITS regions, genes of β tubulin (BT2), and elongation factor α (Tef-1α)) and determine the phylogenetic relationships between isolates. Ninety-four dermatophyte isolates from Costa Rica, Guatemala, Honduras, Mexico, and the Dominican Republic were studied. The isolates presented macro- and micromorphology and conidia size described for the genera Trichophyton, Microsporum, and Epidermophyton. Genotypic analysis classified the isolates into the genera Trichophyton (63.8%), Nannizzia (25.5%), Arthroderma (9.6%), and Epidermophyton (1.1%). The most frequent species were T. rubrum (26 isolates, 27.6%), T. interdigitale (26 isolates, 27.6%), and N. incurvata (11 isolates, 11.7%), N. gypsea and A. otae (nine isolates, 9.6%), among others. The genotypic methods clarified the taxonomic status of closely related species. For instance, the ITS and BT2 markers of T. rubrum/T. violaceum did not differ but the Tef-1α gene did. On the other hand, the three markers differed in T. equinum/T. tonsurans. Therefore, the ITS, BT2, and Tef-1α genes are useful for typing in phylogenetic analyses of dermatophytes, with Tef-1α being the most informative locus. It should be noted that isolate MM-474 was identified as T. tonsurans when using ITS and Tef-1α, but when using BT2, it was identified as T. rubrum. On the other hand, no significant difference was found when comparing the methods for constructing phylogenies, as the topologies were similar. Full article

Background: An increase in the number of recurrent and recalcitrant dermatophytoses calls for a tool to guide the clinician to correlate in vitro minimum inhibitory concentration (MIC) data, antifungal treatment with clinical outcomes. This systematic review aims to explore a possible correlation between one aspect of this, previous antifungal exposure, and clinical outcomes. Methods: A systematic literature search for articles on previous antifungal treatment, treatment outcome, susceptibility methods used, organism (genus/species), and MIC values was conducted. Results: A total of 720 records were identified of which 19 articles met the inclusion criteria. Forty percent of the cases had contact with or travel to India, 28% originated from or had traveled to other countries where treatment unresponsive tinea infections had been reported. Tinea corporis was the most common clinical presentation and the species involved were Trichophyton (T.) indotineae and T. rubrum, followed by T. mentagrophyte/interdigitale complex and T. tonsurans. Nearly all patients had previously been exposed to one or more antifungals. The studies were too heterogeneous to perform a statistical analysis to test if previous antifungal exposure was related to resistance. Conclusions: Only a few studies were identified, which had both sufficient and robust data on in vitro susceptibility testing and clinical treatment failure. Further research on the value of susceptibility testing to improve clinical practice in the management of dermatophyte infections is needed. Full article

Onychomycosis is a fungal disease of the nail that is found worldwide and is difficult to diagnose accurately. This study used metagenomics to investigate the microbiology of 18 clinically diagnosed mycotic nails and two normal nails for fungi and bacteria using the ITS2 and 16S loci. Four mycotic nails were from Bass Coast, six from Melbourne Metropolitan and eight from Shepparton, Victoria, Australia. The mycotic nails were photographed and metagenomically analysed. The ITS2 sequences for T. rubrum and T. interdigitale/mentagrophytes averaged over 90% of hits in 14/18 nails. The high abundance of sequences of a single dermatophyte, compared to all other fungi in a single nail, made it the most likely infecting agents (MLIA). Trichophyton rubrum and T. interdigitale/mentagrophytes were found in Bass Coast and Shepparton while only T. interdigitale/mentagrophytes was found in Melbourne. Two nails with T. interdigitale/mentagrophytes mixed with high abundance non-dermatophyte moulds (NDMs) (Aspergillus versicolor, Acremonium sclerotigenum) were also observed. The two control nails contained chiefly Fusarium oxysporum and Malassezia slooffiae. For bacteria, Staphylococcus epidermidis was in every nail and was the most abundant, including the control nails, with an overall mean rate of 66.01%. Rothia koreensis, Corynebacterium tuberculostearicum, and Brevibacterium sediminis also featured. Full article

Onychomycosis is a fungal infection caused by different etiologic agents, including dermatophytes that specifically colonize keratin-rich substrates. The aim of this work was to investigate mechanical modifications of bovine membranes (used as an in vitro nail model) placed in contact with Trichophyton species. Trichophyton strains were isolated from toenails specimens. The procedure was set up by spreading T. rubrum,T. interdigitale, and T. mentagrophytes strains on Petri dishes with minimal and rich media; after that, bovine membranes were placed in the center. After 27 days, T. interdigitale and T. mentagrophytes significantly reduced the thickness of the colonized membranes, whereas two T. rubrum strains showed the highest degradation limited to the small colonized area. These results were confirmed by SEM images of the colonization profile on membranes. Mechanical analyses performed on membranes were used as an innovative method to evaluate the thickness and structural integrity of membranes variation following fungal colonization. In conclusion, mechanical analyses of substrate may be used as a procedure for the development of a new onychomycosis diagnosis test in order to develop personalized and strain-specific treatment. Full article

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. Full article

Dermatomycoses are one of the most common dermatological infectious diseases. Dermatophytoses, such as tinea pedis (athlete’s foot) in adults and tinea capitis in children, are the most prevalent fungal diseases caused by dermatophytes. The transmission of anthropophilic dermatophytoses occurs almost exclusively through indirect contact with patient-contaminated belongings or environments and, subsequently, facilitates the spread of the infection to others. Hygienic measures were demonstrated to have an important role in removing or reducing the fungal burden. Herein, we evaluated the effectiveness of physical-based methods of laundering, heat drying, and freezing in the elimination of Trichophyton tonsurans, T. rubrum, and T. interdigitale conidia in diverse temperatures and time spectra. Based on our findings, laundering at 60 °C was effective for removing the dermatophyte conidia from contaminated linens. On the contrary, heat drying using domestic or laundromat machines; freezing at −20 °C for 24 h, 48 h, or one week; and direct heat exposure at 60 °C for 10, 30, or 90 min were unable to kill the dermatophytes. These results can be helpful for clinicians, staff of children’s communities, and hygiene practitioners for implementing control management strategies against dermatophytoses caused by mentioned dermatophyte species. Full article

In recent years, we have moved from the sporadic description of terbinafine-resistant (TerR) Trichophyton spp. isolates to the Indian outbreak due to T. indotineae. Population flows have spread TerR worldwide, altering local epidemiology. We conducted a prospective multicentric study to determine the relative frequency of TerR isolates in France (Paris area) and of the newly introduced T. indotineae species. TerR isolates were screened by the terbinafine-containing-agar-medium (TCAM) method and confirmed by EUCAST. Sequencing methods were used to identify isolates to the species/genotype level and to analyze substitutions in the squalene epoxidase gene (SQLE). In total, 3 isolates out of 580 (T. rubrumn = 1; T. interdigitalen = 1; T. indotineaen = 1) grew on TCAM, showed terbinafine resistance by EUCAST and harbored the Phe397Leu (n = 2) or Leu393Ser (n = 1) substitution in the SQLE. ITS-sequencing of isolates of the T. mentagrophytes/interdigitale complex (n = 125) revealed a relative frequency of 4.8% for T. indotineae and the presence of T. mentagrophytes genotype VII. Despite the detection of terbinafine resistance, isolates from this complex remained susceptible to itraconazole, voriconazole and amorolfine. Terbinafine resistance is present in France and the dermatophyte epidemiology is changing. Efficient systems must be implemented to survey the evolution of newly introduced species and to identify TerR isolates. Full article