光滑假丝酵母菌和热带假丝酵母菌环境分离株的氟康唑敏感性与多位点序列分型分析

Fluconazole susceptibility and multi locus sequence typing of Candida glabrata and Candida tropicalis Isolated from environment

目的分析分离自树叶、树皮和腐殖质的光滑假丝酵母菌和热带假丝酵母菌,对其进行耐药性分析和分子流行病学分型,比较环境分离株与临床分离株的进化关系,为流行病学调查及有效控制侵袭性假丝酵母菌感染提供理论支持。方法 2017年9月采集云南省境内环境标本,分离培养提取菌株DNA进行转录间隔区测序鉴定;使用微量肉汤稀释法进行氟康唑药敏实验;采用多位点序列分型进行分子流行病学分型;利用eBURST分析菌株亲缘性。结果采集环境标本200份,分离光滑假丝酵母菌3株和热带假丝酵母菌10株。13株环境分离株均对氟康唑敏感。3株光滑假丝酵母菌的序列型均为ST3,10株热带假丝酵母菌被分为7个二倍体序列(DST),包括4个新DST型(DST813～DST816)。eBURST分析显示,光滑假丝酵母菌均为CC3型,CC730是热带假丝酵母菌环境株的主要型别。结论环境分离株与临床分离株存在相同的起源株。树叶、树皮或腐殖质中的光滑假丝酵母菌和热带假丝酵母菌可能对人类健康造成危害,是人类假丝酵母菌感染的潜在来源。

Objective To understand the drug susceptibility and molecular epidemiological characteristics of Candida glabrata and Candida tropicalis strains isolated from leaves,barks and humus,compare the phylogenetic relationship between environmental isolates and clinical isolates and provide evidence for epidemiological investigation and effective control of invasive Candida infection.Methods A total of 200 environmental samples were collected in Yunnan province.The samples were inoculated on Sabouraud dextrose agar plate for Candida culture and isolation.The genomic DNA of the isolates was extracted,and the isolate species were identified through Internal Transcribed Spacer(ITS) region amplification and sequencing;Antifungal susceptibility testing was performed for each C.glabrata or C.tropicalis isolate by using broth micro dilution reference method;Multi locus sequence typing(MLST) was performed for the genotyping of the isolates.The phylogenetic relationship was analyzed by using eBURST V3 package.Results A total of 3 C.glabrata strains(1.5%) and10 C.tropicalis strains(5.0%) were isolated from 200 environmental samples.All the isolates were sensitive to fluconazole.MLST indicated that ST3 was the only sequence type of C.glabrata.Among 10 C.tropicalis strains,7 DSTs were identified by MLST,including 4 new DSTs(DST813–DST816).CC3 was the major clonal complex of environmental C.glabrata strains.CC730 was the major clonal complex of environmental C.tropicalis strains.Conclusion The environmental isolates might share the same origin strain with clinical isolates.C.glabrata and C.tropicalis isolated from leaves,barks and humus might be the potential source of human infection,posing a serious health threaten to human health.