Non-Dermatophyte Mold Species Obtained from Superficial Clinical Samples: Fusarium spp.

Öz

Non-dermatophyte molds (NDMs) are increasingly recognized as etiological agents of superficial fungal infections, particularly onychomycosis. Among these organisms, Fusarium species have emerged as clinically significant pathogens; however, epidemiological data remain limited in many regions. This study aimed to investigate the distribution of Fusarium isolates obtained from superficial clinical samples over an eight-year period and to evaluate their epidemiological significance using a MALDI-TOF mass spectrometry-based identification method. In this retrospective laboratory-based study, all Fusarium isolates obtained from surface clinical samples sent to the Medical Mycology Laboratory at Cerrahpaşa Medical Faculty Hospital between January 2015 and December 2023 were examined. Isolates were identified at the species level using conventional phenotypic methods and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). A total of 66 Fusarium isolates were included in the study. Nail-derived specimens accounted for 94.0% (62/66) of all samples, whereas skin scrapings represented only 6.0% (4/66). Toenail specimens constituted the majority of isolates (56/66, 84.9%), and fingernail specimens (6/66, 9.1%). Only four isolates originated from cutaneous lesions, including three plantar skin scrapings and one trunk skin scraping. Specifically, Fusarium isolates were obtained from superficial clinical samples throughout the study period and were therefore selected for further epidemiological and identification analyses. The identification of Fusarium species among non-dermatophyte molds and their significant predominance in nail samples points to the potential clinical importance of these species, particularly in onychomycosis. However, since Fusarium species can also be found as contaminants or colonizers in superficial samples, it is important to evaluate these isolates as causative agents by considering diagnostic criteria such as clinical findings, direct microscopic examination, repeated isolation, and appropriate sampling. Our findings support the value of MALDI-TOF MS in accurate and rapid fungal species identification and suggest that the true contribution of Fusarium species to superficial fungal infections may be overlooked in routine clinical practice.

Anahtar Kelimeler

• Fusarium spp.
• Superficial mycoses
• Antifungal resistance
• Echinocandins
• Azoles

Destekleyen Kurum

Istanbul University-Cerrahpaşa Faculty of Medicine Hospital Medical Microbiology Mycology

Proje Numarası

None

Etik Beyan

Ethical Statement: It is declared that scientific and ethical principles have been followed while carrying out and writing this study and that all the sources used have been properly cited (Zeynep Yazgan, Gökhan Aygün). The clinical isolates used in this study are mold Fusarium spp. complex isolates obtained from patient samples sent to the Istanbul University-Cerrahpaşa Faculty of Medicine Hospital Medical Microbiology Mycology Laboratory between 2015 and 2024 and stored at -80°C.

Teşekkür

None

Yüzeysel Klinik Örneklerden Elde Edilen, Dermatofit Olmayan Küf Türleri: Fusarium spp.

Öz

Dermatofit olmayan küfler (NDM’ler), başta onikomikoz olmak üzere yüzeysel mantar enfeksiyonlarının giderek daha fazla tanınan etiyolojik ajanları arasında yer almaktadır. Bu organizmalar arasında Fusarium türleri klinik olarak önemli patojenler olarak ortaya çıkmıştır; ancak birçok bölgede epidemiyolojik veriler sınırlı kalmaktadır. Sekiz yıllık bir dönemde yüzeysel klinik örneklerden elde edilen Fusarium izolatlarının dağılımını araştırmak ve MALDI-TOF kütle spektrometresi tabanlı tanımlama kullanarak epidemiyolojik önemlerini değerlendirmek. Bu retrospektif laboratuvar tabanlı çalışmada, Ocak 2015 ile Aralık 2023 tarihleri arasında Cerrahpaşa Tıp Fakültesi Hastanesi Tıbbi Mikoloji Laboratuvarına gönderilen yüzeysel klinik örneklerden elde edilen tüm Fusarium izolatları incelenmiştir. İzolatlar, geleneksel fenotipik yöntemler ve matris destekli lazer desorpsiyon/iyonizasyon uçuş süresi kütle spektrometresi (MALDI-TOF MS) kullanılarak tür düzeyinde tanımlanmıştır. Çalışmaya toplam 66 Fusarium izolatı dahil edildi. Tırnaktan alınan örnekler tüm örneklerin %94,0'ını (62/66) oluştururken, deri kazıntıları yalnızca %6,0'ını (4/66) temsil ediyordu. İzolatların büyük çoğunluğunu ayak tırnağı örnekleri (56/66, %84,9) ve el tırnağı örnekleri (6/66, %9,1) oluşturdu. Sadece dört izolat deri lezyonlarından elde edildi; bunlardan üçü ayak tabanı deri kazıntısı, biri ise gövde deri kazıntısıydı. Özellikle, Fusarium cinsi, çalışma süresi boyunca yüzeysel mikozlardan elde edilen tüm dermatofit olmayan küf izolatları arasında baskın olarak bulundu. Dermatofit olmayan küfler arasında Fusarium türlerinin saptanması ve tırnak örneklerinin belirgin üstünlüğü, bu türlerin özellikle onikomikozdaki olası klinik önemine işaret etmektedir. Bununla birlikte, Fusarium türleri yüzeysel örneklerde kontaminant veya kolonizan olarak da bulunabileceğinden, bu izolatların etken olarak değerlendirilmesinde klinik bulgular, doğrudan mikroskobik inceleme, tekrarlayan izolasyon ve uygun örnekleme gibi tanısal kriterlerin birlikte değerlendirilmesi önem taşımaktadır. Bulgularımız, doğru ve hızlı mantar tür tanımlamasında MALDI-TOF MS’nin değerini desteklemekte ve Fusarium türlerinin yüzeysel mantar enfeksiyonlarındaki gerçek katkısının rutin klinik uygulamada gözden kaçabileceğini düşündürmektedir.

Anahtar Kelimeler

• Fusarium türleri
• Yüzeysel mikozlar
• Antifungal direnç
• Ekinokandinler
• Azoller

Destekleyen Kurum

Istanbul University-Cerrahpaşa Faculty of Medicine Hospital Medical Microbiology Mycology

Proje Numarası

None

Etik Beyan

Ethical Statement: It is declared that scientific and ethical principles have been followed while carrying out and writing this study and that all the sources used have been properly cited (Zeynep Yazgan, Gökhan Aygün). The clinical isolates used in this study are mold Fusarium spp. complex isolates obtained from patient samples sent to the Istanbul University-Cerrahpaşa Faculty of Medicine Hospital Medical Microbiology Mycology Laboratory between 2015 and 2024 and stored at -80°C.

Teşekkür

None

Kaynakça

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