中国广西地区格特隐球菌菌种复合体的基因型分析

Genotype analysis of Cryptococcus gattii species complex in Guangxi,southern China

目的探讨中国广西地区格特隐球菌菌种复合体的基因型特点、种群结构特征和全球菌株的进化关系。方法收集2014—2018年间分离自临床确诊为隐球菌病患者的隐球菌临床株,利用CGB培养基初步筛选格特隐球菌菌种复合体。采用多位点序列分型方法(MLST)确定基因型。通过MEGA7软件构建系统发育树,利用R语言进行主成分分析。使用微量肉汤稀释法M27-A3方案行体外抗真菌药物敏感性检验。结果120株临床隐球菌中,分离出11株格特隐球菌菌种复合体,6株属于C.deuterogattii(AFLP6/VGII),5株属于C.gattii sensus stricto(AFLP4/VGI)。分离自广西的AFLP6/VGII呈遗传多样性,主要起源进化自南美巴西格特隐球菌菌种复合体。11株分离菌株均对常用抗真菌药物敏感。结论中国广西可能出现高致病性AFLP6/VGII,对格特隐球菌菌种复合体进行有效的全国性监测是必要的。

Objective To explore the genotype characteristics and population structure characteristics of Cryptococcus gattii species complex in Guangxi,China,and to clarify the evolutionary relationship between Guangxi clinical isolates and global strains.Methods Clinical strains of Cryptococci isolated from clinically diagnosed patients with cryptococcosis between 2014 and 2018 were collected,and Cryptococci were preliminarily screened using CGB medium.Multi-site series typing(MLST)was used to determine genotype.Phylogenetic tree construction through MEGA7 software;Principal component analysis using R language.In vitro susceptibility test of antifungal agents was performed using m27-A3 protocol using microbroth dilution.Results Among the 120 strains of clinical Cryptococcus,11 strains of Cryptococcus gattii species complex were isolated,6 strains belonged to C.deuterogattii(AFLP6/VGII),and 5 belonged to C.gattii sensus stricto(AFLP4/VGI).Strains of AFLP6/VGII from Guangxi,were genetically variable and mainly originated and evolved from the Brazilian C.deuterogattii in South America.All isolates were sensitive to antifungal drugs.Conclusion Our study suggests that highly pathogenic AFLP6/VGII may occur in Guangxi China,and effective national surveillance of C.gattii species complex is necessary.