真菌性外耳道炎患者耳道环境菌群结构及多样性

Microbial community structure and diversity in the external auditory canal environment in patients with fungal otitis externa

本研究针对广东地区真菌性外耳道炎患者,采集健康对照组以及患病组外耳道分泌物,提取其总DNA,分析其微生物群落结构、多样性变化以及真菌与细菌之间的相关关系。结果显示,对于细菌而言,致病细菌不仅存在于患病组耳道,也存在于健康人群的耳道当中;对于真菌而言,虽然健康组也检出了真菌,但与细菌不同的是,患病组与健康组的真菌群落差异显著。健康组耳道真菌以担子菌门Basidiomycota为主,该类真菌并不是真菌性外耳道炎的致病菌,而在患病组中,子囊菌门Ascomycota的曲霉属Aspergillus占据绝对优势地位。曲霉是重要的致病菌,在10个患病组样本中,8个样本的曲霉属占比超过90%。此外,真菌与细菌之间,仅有极少数菌种的丰度变化存在正相关关系,多数细菌与真菌的丰度变化并不相关,这意味着在耳道环境中,真菌与细菌群落变化的依存关系不明显。总的来说,健康人群与患病人群的耳道环境均存在致病菌,致病菌的存在并不必然导致耳道炎症的发生,菌群变化只是炎症产生的前提。而曲霉在耳道的大量繁殖是真菌性外耳道炎发病的重要原因,维持一种不利于该菌繁殖的耳道环境,可能是预防真菌性外耳道炎发病的有效措施。

External auditory canal secretion samples were collected from both healthy individuals and patients with fungal otitis externa in Guangdong Province,China.Total DNA extraction was performed,and the bacterial and fungal community structure and diversity were analyzed.The results indicated that pathogenic bacteria were present in the external auditory secretions collected from both infected and healthy individuals.Although fungi were detected in the samples collected from healthy individuals as well,the community structure differed significantly from that in samples collected from infected individuals.With respect to the fungi,the samples collected from healthy individuals primarily contained non-pathogenic basidiomycetes.Aspergillus(phylum:Ascomycota)was the predominant fungal genus present in the samples collected from the infected individuals.The occurrence percentage of pathogenic Aspergillus in 8 out of the 10 samples collected from infected individuals was above 90%.No significant correlation was observed between the changes in the abundances of fungi and bacteria.Mutual dependence between the bacterial and fungal communities was not apparent.Generally,changes in the microbial community structure in the external auditory secretions are an indicator for inflammation.The excessive growth of Aspergillus in the auditory canal is an important cause of external auditory canal fungal disease.Therefore,the maintenance of an external auditory environment that is not conducive to the growth of Aspergillus may serve as an effective step toward the prevention of infection.