念珠菌对唑类药物耐药机理的探讨

文献报道念珠菌对唑类药物耐药机制有三，即膜通透性降低、靶酶改变及靶酶产生过多。本文对２６株分离自艾滋病患者的耐氟康唑白念珠菌及通过诱变获得的白念珠菌ＡＴＣＣ１４０５３五个氟康唑耐药突变菌落的耐药机制进行了初步探讨。根据唑类药物靶酶编码序列设计六对上下之间交叉重叠的引物，分六段（包括相当于调控序列所在部位）将目的基因扩增出来，采用Ｓｏｕｔｈｅｒｎ杂交、限制性片段多态性分析及聚合酶链反应－单链构象多态性分析等方法对所获目的片段进行了分析。结果排除了所有受试菌株因靶酶编码基因缺失而耐药的可能，单链构象多态性分析结果呈阳性，且耐药株之间也存在差异。故此，推测耐药性系因为靶酶编码序列多位点突变造成，这一点尚有待进一步证实。另外，本实验结果不能排除另两条耐药机理的存在

Study of Azole Resistant Mechanisms of Candida albicans

There are three described mechanisms of azole resistance: reduced membrane permeability,alteration in the target fungal enzyme,and over production of the target enzyme.We conducted a study on 26 strains of fluconazole (FCZ) resistant Candida albicans which were isolated from AIDS patients as well as 5 FCZ resistant colonies which were induced from ATCC 14053 by physical(UV) and chemical(diethyl sulfate) means. Firstly, 6 sets of primers were selected from the gene encoding the target enzyme of Candida albicans, and the results of DNA amplification showed that several tested strains were negative for some primers,that is to say:there was no expected DNA band appeared. In order to know whether it lacks of the target enzyme coding gene(in this case,it will be resistant to fluconazole)or not,we used the target enzyme coding gene of Candida albicans ATCC 14053 as a probe to hybridize with the genome DNA of those negative strains,and the result was positive.This indicated that their target genes were existed and probably there was mutation at the site which corresponded to the primers,and especially the latter one.Certainly,this conclusion needs to be further proved.Then,we conducted the polymerase chain reaction single strand conformation polymorphism(PCR SSCP) analysis.There were differences between the resistant strains and the sensitive ones and inter resistant strains also.Therefore,we propose that multi mutation of the gene encoding the target enzyme is probably one of the resistant mechanisms.