The Ptk2-Pma1 pathway enhances tolerance to terbinafine in Trichophyton rubrum.

The increasing prevalence of dermatophyte resistance to terbinafine, a key drug in the treatment of dermatophytosis, represents a significant obstacle to treatment. Trichophyton rubrum is the most commonly isolated fungus in dermatophytosis. In T. rubrum, we identified TERG_07844, a gene encoding a previously uncharacterized putative protein kinase, as an ortholog of budding yeast Saccharomyces cerevisiae polyamine transport kinase 2 (Ptk2), and found that T. rubrum Ptk2 (TrPtk2) is involved in terbinafine tolerance. In both T. rubrum and S. cerevisiae, Ptk2 knockout strains were more sensitive to terbinafine compared with the wild types, suggesting that promotion of terbinafine tolerance is a conserved function of fungal Ptk2. Pma1 is activated through phosphorylation by Ptk2 in S. cerevisiae. Overexpression of T. rubrum Pma1 (TrPma1) in T. rubrum Ptk2 knockout strain (ΔTrPtk2) suppressed terbinafine sensitivity, suggesting that the induction of terbinafine tolerance by TrPtk2 is mediated by TrPma1. Furthermore, omeprazole, an inhibitor of plasma membrane proton pump Pma1, increased the terbinafine sensitivity of clinically isolated terbinafine-resistant strains. These findings suggest that, in dermatophytes, the TrPtk2-TrPma1 pathway plays a key role in promoting intrinsic terbinafine tolerance and may serve as a potential target for combinational antifungal therapy against terbinafine-resistant dermatophytes.

Dual quantitative PCR assays for the rapid detection of Trichophyton indotineae from clinical samples.

Trichophyton indotineae is an emerging species of the Trichophyton mentagrophytes complex (TMC), responsible for an epidemic of widespread hairless skin infections that is frequently (50-70%) resistant to terbinafine. In order to initiate appropriate treatment as quickly as possible without waiting for culture positivity (10-15 days) and molecular identification from the strain, we developed a dual quantitative PCR (qPCR) for the direct detection of T. indotineae in clinical samples. We first designed a T. indotineae-specific qPCR assay (TI-qPCR) targeting a single specific polymorphism in the internal transcribed spacer region. Although none of the 94 non-dermatophyte and 7 dermatophyte species were amplified, this TI-qPCR allowed amplification of other TMC species at a lower yield. With equal amounts (0.1 ng) of DNA per reaction, the mean quantitative cycle (Cq) values for T. indotineae and non-indotineae TMC were 27.9 (±0.1) and 38.9 (±0.3), respectively. Therefore, we normalized this assay against a previously validated pan-dermatophyte qPCR assay (PD-qPCR) and relied on the ΔCq [(TI-qPCR) - (PD-qPCR)] to identify T. indotineae versus other TMC species. Dual assay was validated using 86 clinical samples of culture-confirmed T. indotinea and 19 non-indotineae TMC cases. The mean ΔCq for non-indotineae TMC was 9.6 ± 2.7, whereas the ΔCq for T. indotinea was -1.46 ± 2.1 (P < .001). Setting the ΔCq at 4.5 as a cutoff value resulted in 100% specificity for the detection of T. indotineae. This dual qPCR assay quickly detects T. indotineae from skin scrapings, aiding in early diagnosis and treatment for patients with suspected infection.

Identifying the emerging species Trichophyton indotineae is long and requires to wait for culture positivity. We developed a dual qPCR strategy to detect T. indotineae directly from clinical sample with a 100% sensitivity.

Mapping the Global Spread of T. indotineae: An Update on Antifungal Resistance, Mutations, and Strategies for Effective Management.

INTRODUCTION: The global spread of Trichophyton indotineae presents a pressing challenge in dermatophytosis management. This systematic review explores the current landscape of T. indotineae infections, emphasizing resistance patterns, susceptibility testing, mutational analysis, and management strategies. METHODS: A literature search was conducted in November 2023 using Embase, PubMed, Scopus, and Web of Science databases. Inclusion criteria covered clinical trials, observational studies, case series, or case reports with T. indotineae diagnosis through molecular methods. Reports on resistance mechanisms, antifungal susceptibility testing, and management were used for data extraction. RESULTS AND DISCUSSION: A total of 1148 articles were identified through the systematic search process, with 45 meeting the inclusion criteria. The global spread of T. indotineae is evident, with cases reported in numerous new countries in 2023. Tentative epidemiological cut-off values (ECOFFs) suggested by several groups provide insights into the likelihood of clinical resistance. The presence of specific mutations, particularly Phe397Leu, correlate with higher minimum inhibitory concentrations (MICs), indicating potential clinical resistance. Azole resistance has also been reported and investigated in T. indotineae, and is a growing concern. Nevertheless, itraconazole continues to be an alternative therapy. Recommendations for management include oral or combination therapies and individualized approaches based on mutational analysis and susceptibility testing. CONCLUSION: Trichophyton indotineae poses a complex clinical scenario, necessitating enhanced surveillance, improved diagnostics, and cautious antifungal use. The absence of established clinical breakpoints for dermatophytes underscores the need for further research in this challenging field.

Terbinafine-resistant T. indotineae due to F397L/L393S or F397L/L393F mutation among corticoid-related tinea incognita patients.

Tinea incognita (TI) can mimic other dermatoses, presenting a diagnostic challenge for dermatologists. In some uncertain cases, it is crucial to accurately identify the causative agent using internal transcribed spacer (ITS) sequencing. The global issue of drug-resistant dermatophytosis is increasing, with Trichophyton (T.) indotineae being the main cause. This study presents four cases of TI (diagnosed as eczema) by terbinafine-resistant T. indotineae strains and reviews the current global TI epidemiology based on geographical continent and related conditions. Furthermore, squalene epoxidase (SQLE)-associated resistance mechanisms are evaluated. Lesions caused by terbinafine-resistant T. indotineae strains do not respond to allylamine antifungals, thus allowing the infection to spread. Among T. indotineae isolates, the SQLE F397L substitution is the most prevalent mutation contributing to azole resistance. F397L and L393F replacements in SQLE were detected in all isolates that exhibited high-level resistance. L393S was seen in isolates with low-resistant strains. Interestingly, and for the first time, an L393F amino acid substitution in the SQLE gene product was detected in the Iranian clinical T. indotineae strain. Also, a genomics-based update on terbinafine resistance that focuses on T. indotineae is discussed in this study.

The Domestic Isolation of Terbinafine- and Itraconazole-Resistant Trichophyton indotineae in Chinese Mainland.

BACKGROUND: Trichophyton indotineae, a new species of dermatophytes, has become a significant concern in treating dermatophytosis due to the high level of terbinafine resistance reported in India and even worldwide. OBJECTIVES: This study aimed to report the terbinafine- and itraconazole-resistant T. indotineae in Chinese mainland, by identifying the phylogenetic classification of the isolate strain, and detecting the drug resistance, gene mutation and expression. PATIENTS/METHODS: The skin scales of the patient were cultured on SDA and the isolate was authenticated by DNA sequencing and MALDI-TOF MS. Antifungal susceptibility testing was performed following the M38-A2 CLSI protocol to examine the MICs values of terbinafine, itraconazole, fluconazole, etc. The strain was screened for mutations in the squalene epoxidase (SQLE) gene by Sanger sequencing and detected the expression of CYP51A and CYP51B by qRT-PCR. RESULTS: A multi-resistant ITS genotype VIII sibling of the T. mentagrophytes complex (T. indotineae) was isolated in Chinese mainland. The strain harbored high terbinafine MIC of > 32 µg/mL and itraconazole MIC of 1.0 µg/mL, which was identified a mutation in the squalene epoxidase gene with amino acid substitution (Phe397Leu, mutation 1191C > A). In addition, overexpression of CYP51A and CYP51B was observed. With multiple relapses, the patient finally achieved clinical cure by itraconazole pulse therapy and topical clotrimazole cream for 5 weeks. CONCLUSIONS: The first domestic strain of terbinafine- and itraconazole-resistant T. indotineae from a patient in Chinese mainland was isolated. Itraconazole pulse therapy can be an effective method for the treatment of T. indotineae.

Identification of Microbial Community in Otomycosis by Metagenomic Next Generation Sequencing (mNGS): Potential Implication of Treatment with Terbinafine.

The present study was designed to identify the microbial community as well as to analyze its diversity by means of metagenomic Next Generation Sequencing (mNGS) in 17 patients with otomycosis treated with terbinafine in the Department of Otolaryngology of Shandong Provincial Hospital from June 2021 to June 2022, so as to evaluate the relationship between microbial community and terbinafine resistance. Those 17 patients were divided into two groups, i.e., Terbinafine Effective Group (TEG, n = 14 cases) and Terbinafine Resistance Group (TRG, n = 3 cases) according to the therapy effect, whose microbial community of secretion of external auditory canal was identified using mNGS. We found that the sequence of bacteria was significantly more than that of fungi and, whereas, the difference between the two groups of bacteria was not significant. There were significant differences in fungal community between the two groups. Aspergillus was the main pathogenic fungus of TEG patients while Malassezia was a dominant fungus in TRG patients. In conclusion, the results from this work indicate that Aspergillus terreusis is the main pathogenic fungus in this cohort of otomycosis patients and MNGS sequencing can offer comprehensive information about the microbial community of otomycosis. The fungus community dominated by Malassezia is more likely to be resistant to terbinafine, which provides certain guidance for clinical treatment of otomycosis with terbinafine.

Disinfection trials with terbinafine-susceptible and terbinafine-resistant dermatophytes.

BACKGROUND: Treatment of tinea pedis and onychomycosis is complicated by high rates of reinfection and the emergence of terbinafine-resistant strains of Trichophyton spp. Effective disinfection of contaminated socks is an important measure. Appropriate washing reduces the risk of reinfection and is paramount in treating tinea pedis and onychomycosis. OBJECTIVES: The aim of this study was to describe the effect of commonplace disinfection methods using socks pieces inoculated with terbinafine-resistant or terbinafine-susceptible isolates of Trichophyton spp. METHODS: Sock pieces were inoculated with seven terbinafine-resistant isolates of Trichophyton spp. with known mutations in the SQLE-gene (T. rubrum (n = 3), T. interdigitale (n = 1) and T. indotineae (n = 3)) and six terbinafine-susceptible isolates of Trichophyton spp. (T. rubrum (n = 3) and T. interdigitale (n = 3)). Methods of disinfection included soaking in a quaternary ammonium (QAC) detergent (0.5, 2 and 24 h), freezing at -20°C (0.5, 12 and 24 h), domestic and steam washing (both at 40°C with detergent). Sock pieces were cultured for 4 weeks following disinfection. The primary end point was no growth at the end of week 4. RESULTS: Soaking in a QAC-detergent for 24 h procured at disinfectant rate of 100% (13/13), whilst soaking in 0.5 and 2 h had a disinfectant rate of 46.2% (6/13) and 84.6% (11/13), respectively. Domestic washing (40°C with detergent) produced a disinfectant rate of 7.7% (1/13). Freezing at -20°C (0.5, 12 and 24 h) and steam washing (40°C with detergent) had no disinfectant properties. CONCLUSIONS: Soaking in a QAC-detergent for 24 h effectively disinfected sock pieces contaminated with dermatophytes.

Evaluation of DermaGenius® resistance real-time polymerase chain reaction for rapid detection of terbinafine-resistant Trichophyton species.

BACKGROUND: Treatment-resistant dermatophytosis caused by Trichophyton mentagrophytes/interdigitale complex has emerged as a global public health threat, particularly in endemic countries like India and has spread to many other countries. This veritable spread is alarming due to increase in resistance to terbinafine, which targets the ergosterol biosynthetic pathway by inhibiting the enzyme squalene epoxidase (SQLE). About two third of studies worldwide have reported amino acid substitutions Phe397Leu and Leu393Phe in the SQLE protein to be responsible for high terbinafine MICs. OBJECTIVES: We evaluated the efficacy of the newly developed DermaGenius® Resistance real-time PCR assay to rapidly identify Trichophyton isolates harbouring most common SQLE mutant (Phe397Leu and Leu393Phe) conferring high terbinafine resistance from wild-type susceptible isolates. METHODS: A total of 97 Trichophyton isolates confirmed by ITS sequencing as T. mentagrophytes/interdigitale (recently named T. indotineae n = 90), T. rubrum/T. soudanense (n = 3), T mentagrophytes (n = 2) and T tonsurans (n = 2) were analysed to evaluate DermaGenius® Resistance real-time PCR assay. All 40 T. indotineae isolates exhibiting amino acid substitutions Phe397Leu or Leu393Phe identified by SQLE gene sequencing were evaluated for detection of non-wild-type strains by real-time PCR. Antifungal susceptibility testing for terbinafine was done by CLSI microbroth dilution method. RESULTS: All terbinafine-resistant isolates harbouring amino acid substitutions Phe397Leu or Leu393Phe in SQLE gene were correctly recorded as SQLE mutants by the DermaGenius® Resistance real-time PCR assay. CONCLUSIONS: The DermaGenius® Resistance real-time PCR assay effectively identified Trichophyton species and distinguished wild-type from SQLE mutant genotype that harbour Phe397Leu and Leu393Phe amino acid substitutions.

Antifungal susceptibility testing of dermatophytes: Development and evaluation of an optimised broth microdilution method.

BACKGROUND: Dermatophytosis is one of the most common infections affecting 3%-17% of the population. Resistance to antifungals so far was not of concern in the therapeutic management. However, recent reports of terbinafine-resistant strains in several countries are worrisome making antifungal susceptibility testing inevitable. OBJECTIVES: We aimed to develop and evaluate an optimised broth microdilution assay for antifungal drug susceptibility testing of dermatophytes. METHODS: We first studied the effect of different inocula, incubation temperatures and incubation times to establish an optimised assay. Subsequently, we tested 79 clinical strains of 11 dermatophyte species with 13 antifungals. RESULTS: We found inoculating with 0.5-5 × 104 colony forming units (CFU) and incubating at 29°C ± 1°C for 4 days to be appropriate. Terbinafine was the most active antifungal agent with minimum inhibitory concentration (MIC) values ≤ 0.06 µg/mL, expect for one resistant T mentagrophytes strain, which was isolated from an Indian patient. Also, a majority of MICs of other antifungals that are commonly used to treat dermatophytosis were low, except those of fluconazole. Fluconazole MICs do not correlate with the good efficacy in the clinical management. CONCLUSIONS: Our assay enables fast and reliable susceptibility testing of dermatophytes with a large panel of different antifungals. This helps to improve the therapeutic management of dermatophytosis by detecting resistant strains.

[Terbinafine-resistant dermatophytoses and onychomycosis due to Trichophyton rubrum]. / Terbinafin-resistente Dermatophytosen und Onychomykose durch Trichophyton rubrum.

BACKGROUND: In recent years, therapy-refractory courses of dermatophytoses have increasingly become the focus of attention. The most frequent pathogens are Trichophyton (T.) rubrum and T. mentagrophytes. In addition to local therapy, first-line treatment includes terbinafine, an allylamine antifungal agent that acts by inhibiting squalene epoxidase and thus interfering with ergosterol synthesis. In refractory cases, terbinafine resistance due to point mutation in the squalene epoxidase gene has been frequently detected. OBJECTIVES: The aim is to present specific aspects in the epidemiology of dermatophytoses with terbinafine resistance and to illustrate them on the basis of four patient cases including diagnostic procedures. MATERIALS AND METHODS: A review of handbook knowledge, a selective literature search, and a review of four patient cases were performed. RESULTS: Detection of the terbinafine resistance was performed by in vitro testing using the breakpoint method as well as sequencing of the Trichophyton isolate and detection of the point mutation with amino acid substitution at position L393F or F397L of squalene epoxidase. CONCLUSION: In refractory and recurrent dermatophytoses, terbinafine resistance should be considered, especially in T. mentagrophytes and T. rubrum, and in vitro resistance testing of the dermatophyte and point mutation analysis of squalene epoxidase (SQLE) should be performed. Therapeutically, intermittent administration of itraconazole in combination with antifungal local therapy is recommended. Nevertheless, a recurrent course is to be expected and long-term therapy with itraconazole is usually necessary.

Indian Trichophyton mentagrophytes squalene epoxidase erg1 double mutants show high proportion of combined fluconazole and terbinafine resistance.

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.

Trichophyton indotineae sp. nov.: A New Highly Terbinafine-Resistant Anthropophilic Dermatophyte Species.

In this report, we describe the first isolation of two highly terbinafine (TRF)-resistant Trichophyton interdigitale-like strains from a Nepali patient and an Indian patient with tinea corporis in Japan. These strains (designated NUBS19006 and NUBS19007) exhibited a TRF minimal inhibitory concentration (MIC) of > 32 mg/L and contained a missense mutation (Phe397Leu) in squalene epoxidase (SQLE) gene. The internal transcribed spacer (ITS) region sequences amplified from the isolates (NUBS19006 and NUBS19007) were 99.5% identical to Japanese isolates of T. interdigitale and T. interdigitale strain CBS 428.63. The homology of region sequences were also 97.6% identical to T. mentagrophytes strain CBS 318.56. Moreover, the ITS sequences amplified from the isolates were 100% identical to highly TRF-resistant strains of T. interdigitale, which were isolated in Delhi, India, and harbored mutations in SQLE. The urease test on Christensen's urease agar was positive for T. mentagrophytes and T. interdigitale after 7 days of incubation. On the other hand, the type strain of T. rubrum CBS 100081 T and highly TRF-resistant strains (NUBS19006 and NUBS19007) were negative on Christensen urease agar after 7 and 14 days of incubation. Moreover, NUBS19006 and NUBS19007 were also negative reaction on the hair perforation test. To avoid confusion in the taxonomy of the T. mentagrophytes/T. interdigitale complex, we suggest that the highly TRF-resistant Indian strains be considered a new species independent of T. interdigitale, according to clinical and mycological features.

Antifungal drug susceptibility profile of clinically important dermatophytes and determination of point mutations in terbinafine-resistant isolates.

With regard to increasing number of antifungal-resistant dermatophytes, antifungal susceptibility testing of dermatophytes serves as a useful tool in managing clinical dermatophytosis. This study aimed to determine antifungal susceptibility profile of clinically important dermatophytes and determination of point mutations in terbinafine-resistant isolates. Based on our results, dermatophytosis was confirmed in 97 cases by direct microscopic examination, culture, and sequencing of ITS region. Antifungal susceptibility of 97 dermatophyte isolates distributed in four species including Trichophyton interdigitale (26 isolates), T. rubrum (19 isolates), T. tonsurans (29 isolates), and Epidermophyton floccosum (21 isolates) was assessed to nine antifungal agents using CLSI M38-A2 guidelines. Minimum inhibitory concentration range (MIC range) for luliconazole and terbinafine was 0.001-0.008 µg/ml and 0.003-> 32 µg/ml, compared to 0.03-64 µg/ml for griseofulvin, 0.01-16 µg/ml for itraconazole and voriconazole, 0.03-8 µg/ml for ketoconazole, 0.03-32 µg/ml for econazole, 0.03-1 µg/ml for lanoconazole, and 0.01-4 µg/ml for butenafine. Trichophyton tonsurans was the most susceptible (MIC = 0.006 µg/ml) and E. floccosum was the most resistant (MIC = 0.02 µg/ml) species to terbinafine. Terbinafine resistance was reported for two species, i.e., T. rubrum and T. tonsurans at the total rate of 2% which was due to Leu393Phe substitution in both species. Taken together, our results assist clinicians and prompt the current knowledge about the necessity of antifungal susceptibility testing to select effective strategies for management of clinical cases of dermatophytosis.

High terbinafine resistance in Trichophyton interdigitale isolates in Delhi, India harbouring mutations in the squalene epoxidase gene.

In the last few years, infections caused by dermatophytes along with a concomitant increase in the number of difficult to treat cases have increasingly been recognised, indicating that dermatophytosis remains a challenging public health problem. The majority of infections are caused by Trichophyton rubrum and Trichophyton mentagrophytes complex. Terbinafine, an allylamine antifungal used orally and topically is considered to be a first-line drug in the therapy of dermatophyte infections. Terbinafine resistance has been predominately attributed to point mutations in the squalene epoxidase (SQLE) target gene a key enzyme in the ergosterol biosynthetic pathway leading to single amino acid substitutions. Here, we report the largest series of 20 terbinafine-resistant Trichophyton interdigitale isolates obtained predominately from cases of tinea corporis/cruris in three hospitals in Delhi, India exhibiting elevated MICs (4 to ≥32 µg/mL) to terbinafine and all harbouring single-point mutations Leu393Phe or Phe397Leu in the SQLE gene. In 12 (60%) T. interdigitale isolates, the Phe397Leu substitution was observed, whereas in the remaining 8 (40%) isolates the substitution Leu393Phe was reported for the first time in T. interdigitale. Furthermore, 10 susceptible T. interdigitale isolates (0.125-2 µg/mL) had a wild-type genotype. Remarkably, considerably high terbinafine resistance rate of 32% was observed among 63 T. interdigitale isolates identified by sequencing of the internal transcribed spacer region. This high level of terbinafine resistance of Indian dermatophyte isolates is worrisome warranting antifungal susceptibility testing and mutation analysis for monitoring this emerging resistance.

Epidemiological trends, antifungal drug susceptibility and SQLE point mutations in etiologic species of human dermatophytosis in Al-Diwaneyah, Iraq.

Dermatophytes show a wide geographic distribution and are the main causative agents of skin fungal infections in many regions of the world. Recently, their resistance to antifungal drugs has led to an obstacle to effective treatment. To address the lack of dermatophytosis data in Iraq, this study was designed to investigate the distribution and prevalence of dermatophytes in the human population and single point mutations in squalene epoxidase gene (SQLE) of terbinafine resistant isolates. The identification of 102 dermatophytes isolated from clinical human dermatophytosis was performed through morphological and microscopic characteristics followed by molecular analysis based on ITS and TEF-1α sequencing. Phylogeny was achieved through RAxML analysis. CLSI M38-A2 protocol was used to assess antifungal susceptibility of the isolates to four major antifungal drugs. Additionally, the presence of point mutations in SQLE gene, which are responsible for terbinafine resistance was investigated. Tinea corporis was the most prevalent clinical manifestation accounting for 37.24% of examined cases of dermatophytosis. Based on ITS, T. indotineae (50.98%), T. mentagrophytes (19.61%), and M. canis (29.41%) was identified as an etiologic species. T. indotineae and T. mentagrophytes strains were identified as T. interdigitale based on TEF-1α. Terbinafine showed the highest efficacy among the tested antifungal drugs. T. indotineae and T. mentagrophytes showed the highest resistance to antifungal drugs with MICs of 2-4 and 4 µg/mL, while M. canis was the most susceptible species. Three of T. indotineae isolates showed mutations in SQLE gene Phe397Leu substitution. A non-previously described point mutation, Phe311Leu was identified in T. indotineae and mutations Lys276Asn, Phe397Leu and Leu419Phe were diagnosed in T. mentagrophytes XVII. The results of mutation analysis showed that Phe397Leu was a destabilizing mutation; protein stability has decreased with variations in pH, and point mutations affected the interatomic interaction, resulting in bond disruption. These results could help to control the progression of disease effectively and make decisions regarding the selection of appropriate drugs for dermatophyte infections.

Multi-drug resistance Trichophyton indotineae in a stray dog.

A 2.5-year-old stray dog showed signs of hair loss, mild skin crusting, and redness on extremities and trunk. The etiologic agent was confirmed as Trichophyton indotineae by sequencing of ITS region. Using the Clinical and Laboratory Standards Institute (CLSI M38-A3) guideline, antifungal susceptibility testing showed multidrug resistance phenotype against terbinafine (16 µg/mL-1), itraconazole, and some other tested antifungals (minimum inhibitory concentration, MIC≥16 µg/mL-1). However, luliconazole was found to be active in- vitro (0.016 µg/mL-1). Upon further studies, sequencing of SQLE gene showed an amino acids substitution of Phe397Leu and Ala448Thr, which is potentially linked to terbinafine resistance in Trichophyton species.

Increased terbinafine resistance among clinical genotypes of Trichophyton mentagrophytes/T. interdigitale species complex harboring squalene epoxidase gene mutations.

Terbinafine resistance has become epidemic as an emerging problem in treatment of dermatohpytosis. This could be attributed in part to a point mutation in the squalene epoxidase (SQLE) gene. In this study, point mutations in the SQLE gene were studied in T. rubrum and T. mentagrophytes/T. interdigitale species complex as two main causative agents of dermatophytosis. Antifungal susceptibility of clinical isolates of T. rubrum (n = 27) and T. mentagrophytes/T. interdigitale (n = 56) was assessed using the M38-3rd edition CLSI method. The SQLE gene and ITS region were sequenced for all the fungal strains, and the mutation sites and genotypes of the terbinafine-resistant strains were characterized. The results demonstrated that, in T. rubrum, the minimum inhibitory concentration of terbinafine (MIC50 and MIC90) was 0.03 µg/ml, and the geometric mean (G mean) concentration was 0.02. For the T. mentagrophytes complex, the MIC50 and MIC90 were 0.03 and 1.0 µg/ml, respectively, and the G mean concentration was 0.04 µg/ml. Four out of the five resistant strains were T. indotineae harboring the F397L and Q408L mutations, while the last one was T. mentagrophytes genotype VII, which harbors the F397L mutation. T. indotineae was the prominent causative agent of terbinafine resistance, with 80 % of the isolates, and T. mentagrophytes genotype VII was introduced as a new genotype in the terbinafine-resistant T. mentagrophytes complex. Our findings further substantiate the importance of antifungal susceptibility testing in selecting the choice of drug for effective treatment of dermatophytosis and highlight the importance of screening dermatophyte species for point mutations responsible for newly developed resistant strains to improve the current knowledge of overcoming infections caused by resistant species.

Time to Think Antifungal Resistance Increased Antifungal Resistance Exacerbates the Burden of Fungal Infections Including Resistant Dermatomycoses.

Increased antifungal resistance is exacerbating the burden of invasive fungal infections, as well as potentially contributing to the increase in resistant dermatomycoses. In this commentary, we focus on antifungal drug resistance, in contrast to antibacterial resistance. We provide a brief historical perspective on the emergence of antifungal resistance and propose measures for combating this growing health concern. The increase in the incidence of invasive and cutaneous fungal infections parallels advancements in medical interventions, such as immunosuppressive drugs, to manage cancer and reduce organ rejection following transplant. A disturbing relatively new trend in antifungal resistance is the observation of several fungal species that now exhibit multidrug resistance (eg, Candida auris, Trichophyton indotineae). Increasing awareness of these multidrug-resistant species is paramount. Therefore, increased education regarding potential fungus-associated infections is needed to address awareness in the general healthcare setting, which may result in a more realistic picture of the prevalence of antifungal-resistant infections. In addition to education, increased use of diagnostic tests (eg, micro and macro conventional assays or molecular testing) should be routine for healthcare providers facing an unknown fungal infection. Two critical barriers that affect the low rates for Antifungal Susceptibility Testing (AST) are low (or a lack of) sufficient insurance reimbursement rates and the low number of qualified laboratories with the capacity to perform AST. The ultimate aim is to improve the quality of patient care through fungal identification, diagnosis, and, where appropriate, susceptibility testing. Here we propose an all-encompassing call to action to address this emerging challenge.

Towards an Early Clinical and Biological Resistance Detection in Dermatophytosis: About 2 Cases of Trichophyton indotineae.

Trichophyton indotineae causes resistant dermatophytosis to terbinafine. The global spread of terbinafine-resistant Trichophyton indotineae strains with mutations in the squalene epoxidase gene is a major issue. This emerging species is now more frequently isolated in Europe and we report here two cases of T. indotineae tinea corporis in Switzerland, one with in vitro resistance to terbinafine and a second with in vitro susceptibility but a clinical resistance. Mycology isolation from cultures and sequencing ITS gene were used to confirm T. indotineae infection. In vitro antifungal susceptibility was tested in a microplate with a colorimetric detection of fungal viability for the determination of the minimal inhibitory concentration (MIC). Facing these emerging resistances and since there are a limited number of antifungal agents available to treat dermatophytosis, the early detection of terbinafine resistance should be a prerequisite in the management of T. indotineae infections.

First case report of tinea corporis caused by Trichophyton indotineae in Latin America.

A case of tinea corporis by Trichophyton indotineae observed in Argentina is presented. The patient had a history of having spent 18 months in Tulum, Mexico. She was suffering from tinea corporis in the anterior region of both thighs and the gluteal area. A mycological study was performed and T. mentagrophytes complex was isolated. The fungus was later identified as T. indotineae by DNA sequencing and treatment with SUBA-itraconazole was initiated with good clinical response.