Clinical and Mycological Profiles of Chronic and Recalcitrant Dermatophytosis: Türkiye, 2022–2024

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.

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Journal
Mycopathologia
Published
2026-02-18
DOI
https://doi.org/10.1007/s11046-026-01058-5
Primary Topic
Nail Diseases and Treatments
Type
article
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article

Clinical and Mycological Profiles of Chronic and Recalcitrant Dermatophytosis: Türkiye, 2022–2024

Ayşe Sultan Karakoyun, G Erkose-Genc, Daniela Kolarczyková, Sertaç Sever et al.
Mycopathologia
Nail Diseases and Treatments
article

Clinical and Mycological Profiles of Chronic and Recalcitrant Dermatophytosis: Türkiye, 2022–2024

Ayşe Sultan Karakoyun, G Erkose-Genc, Daniela Kolarczyková, Sertaç Sever, Ferit Kuşçu, Yasemin Erdem, Rebiay Kıran, Sinan Özçelik, Vít Hubka, Zayre Erturan, Kaan Taşolar, Ayşe Tülin Mansur, Irem Mantar, Tuğba Atak, İlayda Muslu, Pavlína Lysková, Oğuzhan Bingöl, Murat Durdu, Feyzahan Uzun, Melisa Özay, Hazal Kandemir, Aslan Yürekli, SELAMİ AYKUT TEMİZ, Macit Ilkit, Tuğba Falay-Gür, Büşra Acar-Mantar, Özlem Su-Küçük, Funda Aktürk-Gözel, Abdullah Demirbaş, Mehmet Kamil Mülayim, Sybren de Hoog, İsa An, Yeşim Yayla-Öztürk, Tuğba Tehçi, Rabia Öztaş-Kara, Gözde Ulutaş-Demirbaş
article en

Abstract

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.

MycopathologiaVol. 191(2)
Sakarya University (TR), Leiden University (NL), Ministry of Health (TR), Radboud University Nijmegen (NL), Başkent University (TR), Czech Academy of Sciences (CZ), Charles University (CZ), Radboud University Medical Center (NL), State Hospital (GB), Bezmiâlem Vakıf Üniversitesi (TR), Turkish Society of Hematology (TR), Necmettin Erbakan University (TR), Sivas State Hospital (TR), Antalya Eğitim ve Araştırma Hastanesi (TR), Westerdijk Fungal Biodiversity Institute (NL), Canisius-Wilhelmina Ziekenhuis (NL), Sakarya Eğitim ve Araştırma Hastanesi (TR), Czech Academy of Sciences, Institute of Microbiology (CZ), Şanlıurfa Mehmet Akif İnan Eğitim ve Araştırma Hastanesi (TR), Sağlık Bilimleri Üniversitesi (TR), Research Institute of Inorganic Chemistry (CZ), Istanbul Eye Hospital (TR), Yeditepe University Hospital (TR), Antalya IVF (TR), Kahramanmaraş Sütçü İmam University (TR), Kocaeli Üniversitesi (TR), Cukurova University (TR), Istanbul University (TR), Muğla University (TR)
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