Cellular and Molecular Research Center, Yasuj University of Medical Sciences, Yasuj, Iran.
Department of Medical Mycology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
J Med Microbiol. 2019 Apr;68(4):585-590. doi: 10.1099/jmm.0.000948. Epub 2019 Feb 25.
Otomycosis is a mycotic infection of the external auditory canal and can be caused by a wide range of fungal species. In this study, we aimed to identify fungal isolates from patients suspected of otomycosis.
External ear canal samples were taken from patients referred to the outpatient department of Shahid-Mofatteh Clinic in the city of Yasuj, Iran, and examined by direct microscopy and culture. DNA of the isolated fungi was tested by internal transcribed spacer PCR restriction fragment length polymorphism analysis for identification of yeasts and β-tubulin sequencing for identification of Aspergillus species.
Among 275 patients suspected of otomycosis, 144 cases (83 female and 61 male) were confirmed with otomycosis. For 89% (n=128) of positive cultures, microscopy was also positive, while there were no cases with a microscopy-positive and culture-negative result. The predominant predisposing factor was self-cleaning of the external ear using unhygienic tools, and the main risk occupation was 'housewife'. The most common isolated fungi were typically Aspergillus (n=120), including 73 isolates of Aspergillus section Nigri, 43 of section Flavi, 3 of section Terrei and 1 of section Fumigati. After sequencing, 44 out of 73 strains primarily identified as Aspergillus niger turned out to be Aspergillus tubingensis. Thirty-five isolates were identified as Candida, including Candida parapsilosis (n=22), Candida albicans (n=12) and Candida tropicalis (n=1).
Aspergillus tubingensis was the most common species involved in otomycosis. This work corroborates the difficulty of precise identification of species within the black Aspergilli by morphological characteristics.
耳真菌病是外耳道的真菌感染，可由多种真菌引起。本研究旨在从疑似耳真菌病患者中分离真菌。
从伊朗亚苏季市沙希德-莫法特诊所的门诊患者的外耳耳道样本中采集样本，通过直接显微镜检查和培养进行检查。通过内部转录间隔区 PCR 限制性片段长度多态性分析对分离真菌的 DNA 进行检测，以鉴定酵母菌，并用β-微管蛋白测序鉴定曲霉属物种。
在 275 例疑似耳真菌病患者中，有 144 例（83 名女性和 61 名男性）被确诊为耳真菌病。89%（n=128）的阳性培养物显微镜检查也为阳性，而没有显微镜检查阳性和培养物阴性的情况。主要的致病因素是使用不卫生的工具自行清洁外耳，主要的高危职业是“家庭主妇”。最常见的分离真菌通常为曲霉属（n=120），其中包括 73 株黑曲霉节，43 株黄曲霉节，3 株地霉节和 1 株烟曲霉节。测序后，73 株主要鉴定为黑曲霉的菌株中，有 44 株为构巢曲霉。35 株被鉴定为假丝酵母，包括近平滑假丝酵母（n=22）、白色念珠菌（n=12）和热带假丝酵母（n=1）。
构巢曲霉是耳真菌病最常见的病原体。这项工作证实了通过形态特征准确鉴定黑曲霉种的困难。
