Trichophyton indotineae, formerly known as T. mentagrophytes internal transcribed spacer (ITS) genotype VIII, has been recognized over the last decade due to its high virulence and resistance to treatment. Its accurate identification in routine mycology laboratories remains challenging, as it shares phenotypic traits and substantial rDNA ITS similarity with T. mentagrophytes and T. interdigitale. This study aimed to identify more divergent and stable sequences via whole-genome comparisons between T. indotineae and T. interdigitale to facilitate highly specific targeting of T. indotineae using a validated quantitative polymerase chain reaction (qPCR)-based method. Our whole-genome comparison revealed at least 22 unique sequences of T. indotineae compared to T. interdigitale and revealed the divergence of the former from the reference genomes of other Trichophyton species. Among these, a 499 bp segment was identified as the most genetically distinct sequence within the T. indotineae genome. Seventy-three dermatophyte strains [T. indotineae (n = 66), non-T. indotineae (n = 7)], were tested using our qPCR assay targeting the above-mentioned stable 499-bp region. Regarding analytical performance, our T. indotineae-specific qPCR assay exhibited high sensitivity (93.3%) and specificity (100%), with a detection limit of ~ 15 genomic copies. Our approach has the potential to establish highly sensitive and specific qPCR assays without relying on specialized assay designs for single nucleotide polymorphisms in the ITS or other loci. This approach offers a practical solution for updating molecular diagnostics, particularly for novel taxa such as T. indotineae, for which limited gene data are available in public databases.

This study investigated the treatment outcomes of 91 patients with chronic and recalcitrant dermatophytosis from 20 hospitals in Türkiye between June 2022 and March 2024, as well as the in vitro antifungal susceptibility and squalene epoxidase ( SQLE ) substitution profiles of the dermatophytes obtained from these patients. Molecular identification by sequencing 91 isolates, revealed 76 Trichophyton mentagrophytes ITS genotype VIII (TmVIII; also known as T . indotineae ) isolates, 13 Trichophyton rubrum , one Trichophyton tonsurans , and one Microsporum canis . The Phe397Leu substitution predominated in the SQLE , and Tyr414His co-occurred in nine TmVIII isolates. Five novel substitutions were observed in TmVIII. Among 13 T . rubrum isolates, three showed different SQLE substitution patterns compared to the wild-type strain. EUCAST antifungal susceptibility testing revealed high minimum inhibitory concentrations (MICs) for terbinafine (TRB) (> 0.25 mg/L) and for fluconazole (FLZ) (≥ 16 mg/L), indicating resistance in most TmVIII isolates. Of the 91 patients, 83 responded to FLZ, itraconazole (ITZ), TRB, or voriconazole-based regimens. While adjunct therapy with FLZ and resveratrol (RES) led to improvement in 28/29 patients despite their high in vitro inhibition concentrations, ITZ and curcumin (CUR) therapy was successful in 3/3 patients. However, the in vitro efficiency of CUR could not be evaluated. These findings highlight the local occurrence of specific SQLE substitutions, underscore the importance of EUCAST MIC testing combined with SQLE sequencing for surveillance, and support further evaluation of RES and CUR as an adjunct in TRB-resistant TmVIII.

Clinical and mycological data are essential for the optimal management of patients with Candida vaginitis (CV), particularly in cases of (i) azole-resistant C. albicans vaginitis, (ii) recurrent CV, and (iii) CV in pregnant women. The present retrospective single-center study investigated the antifungal activity of six commonly used antifungals against randomly selected vaginal isolates recovered from 68 pregnant women in Adana, Türkiye, including C. albicans, petite C. glabrata, non-petite C. glabrata, and C. krusei, using the disk diffusion method at pH 4 and 7. Furthermore, the antifungal activities of fluconazole and itraconazole were also assessed using the broth microdilution method. For all isolates, the mean inhibition zone diameters were narrower for itraconazole and ketoconazole and larger for miconazole at pH 4 than pH 7 (p < 0.05). For nystatin, zone diameters were wider in C. albicans and petite C. glabrata at pH 4 (p < 0.001 and p < 0.001). Remarkably, clotrimazole was more active at pH 4 than at pH 7, except against non-petite C. glabrata isolates. Based on the broth microdilution results, the resistance rate was higher at pH 4 than at pH 7 in all isolates. Candida glabrata petite isolates exhibited MIC values 2 to 5 times higher than those of the non-petite isolates for both fluconazole and itraconazole. This study highlights the potent activity of topical antifungals (miconazole, nystatin, and clotrimazole) for the treatment of CV in pregnant women and highlights the need to identify petite and non-petite mutants of vaginal C. glabrata isolates to obtain more reliable data and for antifungal susceptibility testing prior to decision-making. The results of the two antifungal susceptibility methods were compared for C. albicans and C. glabrata isolates, and the reliability of the disk diffusion test was discussed.

Background: Chronic and recalcitrant dermatophytosis has become increasingly problematic in dermatology practice, largely due to emerging antifungal resistance, affecting not only terbinafine but also azoles. Among the causative agents, Trichophyton indotineae has emerged as a key pathogen associated with treatment failure, extensive disease, and frequent relapse, even in immunocompetent patients. Objective: This study aimed to evaluate and compare two rapid molecular diagnostic approaches: A commercial multiplex qPCR assay (DermaGenius Resistance Multiplex PCR, DermaGenius RMP) and a T . indotineae‐ specific in‐house qPCR assay, focusing on their practical value for early detection of recalcitrant dermatophyte infections and terbinafine resistance in routine dermatology practice. Methods: Sixty‐four dermatophyte isolates obtained from patients with chronic or treatment‐resistant dermatophytosis in Türkiye wereanalysed. Species identification and detection of squalene epoxidase (SQLE) gene mutations associated with terbinafine resistance were performed using DermaGenius RMP and the in‐house T . indotineae ‐specific qPCR assay, with confirmatory ITS/SQLE sequencing and CLSI microbroth dilution antifungal susceptibility testing. Results: Overall concordance between the two qPCR methods was 93.8% (κ = 0.74, z = 5.99, p < 0.001) for T . indotineae identification. Most recalcitrant cases were caused by T . indotineae , and SQLE mutations were detected in > 90% of these isolates, consistent with the observed clinical resistance. DermaGenius RMP enabled rapid, standardised detection of terbinafine resistance–associated mutations suitable for routine diagnostics, whereas the in‐house qPCR provided highly specific identification of T . indotineae . Notably, 10 T . indotineae isolates harboured the SQLE F397L substitution despite terbinafine susceptibility. Conclusions: Rapid molecular diagnostics, particularly qPCR‐based assays, provide actionable information early in the course of infection. In this study, both assays showed comparable performance for T . indotineae detection. Prompt identification of T . indotineae and associated resistance mutations may help avoid ineffective antifungal therapy, reduce chronicity, and support rational treatment decisions in routine clinical practice.

Dermatophyte infections have evolved in both clinical presentation and etiological profiles, with chronic, recurrent, and widespread forms becoming increasingly prevalent and therapeutically challenging over the past decade. These infections are predominantly caused by Trichophyton indotineae (ITS genotype VIII), a member of the Trichophyton mentagrophytes complex. The virulence mechanisms of T . indotineae remain poorly understood. To elucidate potential pathogenic factors, we investigated hemolytic and co-hemolytic (CAMP-like) activities in dermatophytes associated with recalcitrant dermatophytosis. A total of 127 isolates (117 T. indotineae , 5 T. rubrum , 3 T. tonsurans , and 2 Microsporum canis ) were examined using Columbia agar supplemented with 5% ovine (COA) or equine erythrocytes (CEA). Hemolysis was more consistently observed on COA (119 isolates) than on CEA (44 isolates) following 7-day incubation at 27 °C. Additional incubation at 36 °C up to 7 days was required to enhance hemolysis detection on CEA. Overall, 93.7% of isolates exhibited hemolytic activity, whereas only 3.1% demonstrated co-hemolytic activity. Among T . indotineae isolates, 97.4% were hemolytic. These findings underscore the importance of characterizing virulence traits in dermatophytes. Additional studies are needed to clarify the role of hemolysis in chronic and recalcitrant infections, with the goal of identifying novel therapeutic targets.