Department of Medical Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Pour Sina st., Keshavarz Blvd., Tehran, Iran.
Department of Medical Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Pour Sina st., Keshavarz Blvd., Tehran, Iran; Students' Scientific Research Center, Tehran University of Medical Sciences, Tehran, Iran.
J Mycol Med. 2018 Jun;28(2):279-284. doi: 10.1016/j.mycmed.2018.02.003. Epub 2018 Mar 11.
Aspergillus niger is the most commonly reported etiology of otomycosis based on morphological characteristics. This fungus is a member of Aspergillus section Nigri, a set of morphologically indistinguishable species that can harbor various antifungal susceptibility patterns. The aim of this study was to accurately identify and determine the susceptibility pattern of a set of black aspergilli isolated from otomycosis patients.
Forty-three black Aspergillus isolates from otomycosis patients were identified by using the PCR-sequencing of the β-tubulin gene. Furthermore, the susceptibility of isolates to three antifungal drugs, including fluconazole (FLU), clotrimazole (CLT) and nystatin (NS), were tested according to CLSI M38-A2. The data were analyzed using the SPSS software (version 15).
The majority of isolates were identified as A. tubingensis (32/43, 74.42%) followed by A. niger (11/43, 25.58%). The lowest minimum inhibitory concentration (MIC) values were observed for NS with geometric means (GM) of 4.65μg/mL and 4.83μg/mL against A. tubingensis and A. niger isolates, respectively. CLT showed wide MIC ranges and a statistically significant inter-species difference was observed between A. tubingensis and A. niger isolates (P<0.05). FLU was inactive against both species with GMs>64μg/mL.
Species other than A. niger can be more frequent as observed in our study. In addition, considering the low and variable activity of tested antifungal drugs, empirical treatment can result in treatment failure. Accurate identification and antifungal susceptibility testing of isolates is, however, recommended.
根据形态学特征，黑曲霉是耳真菌病最常报告的病因。这种真菌是黑曲霉组的成员，这组形态上无法区分的物种可以携带各种抗真菌药物敏感性模式。本研究的目的是准确鉴定和确定一组从耳真菌病患者中分离出的黑曲霉的敏感性模式。
使用β-微管蛋白基因的 PCR 测序对 43 株来自耳真菌病患者的黑曲霉分离株进行鉴定。此外，根据 CLSI M38-A2 测试了分离株对三种抗真菌药物（氟康唑（FLU）、克霉唑（CLT）和制霉菌素（NS））的敏感性。使用 SPSS 软件（版本 15）分析数据。
大多数分离株被鉴定为 A. tubingensis（32/43，74.42%），其次是 A. niger（11/43，25.58%）。对 NS 的最低最小抑菌浓度（MIC）值观察到最低，几何平均值（GM）分别为 4.65μg/mL 和 4.83μg/mL，针对 A. tubingensis 和 A. niger 分离株。CLT 显示出广泛的 MIC 范围，并且在 A. tubingensis 和 A. niger 分离株之间观察到统计学上显著的种间差异（P<0.05）。FLU 对两种物种均无活性，GM>64μg/mL。
与我们的研究观察到的情况一样，除了 A. niger 之外的其他物种可能更频繁。此外，考虑到测试抗真菌药物的活性低且变化大，经验性治疗可能导致治疗失败。然而，建议对分离株进行准确的鉴定和抗真菌药敏试验。
