深圳地区新生隐球菌和格特隐球菌的临床分子流行病学

Molecular epidemiological study of Cryptococcus neoformans and Cryptococcus gattii in Shenzhen

目的 通过对深圳地区新生隐球菌和格特隐球菌临床分离株进行分子流行病学调查,分析其种、变种、基因型和交配型的构成.方法 受试菌株为从临床标本中分离的55株隐球菌,利用刀豆氨酸-甘氨酸-溴麝香草酚蓝培养法区分新生隐球菌和格特隐球菌;利用M13的PCR指纹分型法鉴定基因型;利用变种和交配型特异性引物扩增分型法,区分新生隐球菌格鲁比变种、新生变种和格特隐球菌,同时鉴定α交配型和a交配型;利用GEF1-限制性片段长度多态性分析法同步鉴定和验证受试株的基因型和交配型;对VGⅡ基因型菌株进行IGS1序列类型的分析.结果 55株临床株中,52株为新生隐球菌,均为格鲁比变种、VN Ⅰ基因型和a交配型;3株为格特隐球菌,包括1株VG Ⅰ基因型、α交配型和2株VGⅡ基因型、a交配型.2株VGⅡ基因型菌株的IGS1序列类型为Ⅱ型.结论 深圳地区隐球菌致病菌株中绝大多数仍为新生隐球菌格鲁比变种、VN Ⅰ基因型和α交配型.存在少数格特隐球菌菌株,其中包括导致国外高发病率的VGⅡ基因型,后者的IGS1序列类型与VGⅡb基因亚型一致.

Objective To study the epidemiological features of Cryptococcus neoformans and Cryptococcus gattii isolated from clinical samples in Shenzhen and to elucidate the distribution of species,varieties,genotypes and mating types within the strains tested.Methods The strains involved in this study were 55 cryptococcal strains isolated from our clinical samples.The canavanine-glycine bromthymolblue （CGB） culture was performed to distinguish Cryptococcus neoformans from Cryptococcus gattii.The genotype was characterized by polymerase chain reaction （PCR） fingerprinting with primer M13.The Cryptococcus gattii species and varieties of grubii and neoformans together with two opposite mating type α and a were identified by PCR with variety-specific and mating type-specific primers.The GEF1-restriction fragment length polymorphism analysis was conducted to simultaneously determine the genotype and mating types of strains tested.The sequence type of IGS1 region was analyzed for the VG Ⅱ genotype.Results Of the 55 tested cryptococcal strains,52 were Cryptococcus neoformans,all of which were var.grubii,genotype VN Ⅰ and mating type α.The remaining 3 strains were Cryptococcus gattii,among which,one was genotype VG Ⅰ and mating type α,and two were genotype VG Ⅱ and mating type α.The two VGⅡ genotype strains belonged to the sequence type Ⅱ.Conclusions The strains belonging to the Cryptococcus neoformans var.grubii,genotype VN Ⅰ and mating type α predominate in causative pathogens of cryptococcosis in Shenzhen.Cryptococcus gattii accounts for minority of the cryptococcal isolates,and the highly pathogenic VG Ⅱ genotypes in foreign countries are also characterized.The sequence types of IGS1 region of the two VG Ⅱ strains are in accord with VG Ⅱb sub-genotype.