侵袭性白假丝酵母感染ERG3基因突变及表达

Mutation and expression of ERG3 gene in Candida albicans causing invasive infection

目的分析侵袭性白假丝酵母感染ERG3基因突变及表达情况。方法收集2018年1月-2018年12月亳州市人民医院发生IFI的住院患者体液标本,分离白假丝酵母。采用微量肉汤稀释法对菌株进行氟康唑敏感性实验,采用聚合酶链反应(PCR)扩增ERG3基因并测序分析突变位点,比较不同氟康唑敏感性菌株ERG3基因表达情况。结果所有标本共分离出白假丝酵母239株,以痰液(67.36%)为主,其次为阴道分泌物(12.13%)、尿液(10.04%);239株白假丝酵母共检出221株氟康唑敏感株(92.47%)、17株氟康唑耐药株(7.11%)及1株剂量依赖敏感株(0.42%);随机选择10株氟康唑敏感株和4株氟康唑耐药株进行ERG3基因扩增,14株白假丝酵母ERG3基因序列中共发现28个点突变,包括24个(85.71%)同义突变,4个(14.29%)错义突变,其中同义突变位点为C602T、T432C、C438T,错义突变位点为I340L、V374G、P902L和V1076A;氟康唑耐药株ERG3基因高表达率明显高于敏感株。结论侵袭性白假丝酵母感染对氟康唑具有一定耐药性,其耐药性可能与ERG3基因错义突变I340L、V374G、P902L和V1076A有关。

OBJECTIVE To analyze the mutation and expression of ERG3 gene in Candida albicans causing invasive fungal infection.METHODS The body fluid specimens were collected from the patients with IFI who were hospitalized in the People’s Hospital of Bozhou from Jan 2018 to Dec 2018,the C.albicans strains were isolated.Fluconazole susceptibility testing was carried out for the strains by using micro broth dilution method,the ERG3 gene was amplified by polymerase chain reaction(PCR),the mutation sites were sequenced and analyzed,and the expression of ERG3 gene was compared among the fluconazole-sensitive strains.RESULTS Totally 239 strains of C.albicans were isolated from all of the specimens,67.36%of which were isolated from sputum specimens,12.13%were isolated from vaginal secretions,and 10.04%were isolated from urine specimens.Among the 239 strains of C.albicans,there were 221(92.47%)fluconazole-sensitive strains,17(7.11%)fluconazole-resistant strains and 1(0.42%)dose-dependent sensitive strain.10 fluconazole-sensitive strains and 4 fluconazole-resistant strains were randomly selected for ERG3 gene amplification,and a total of 28 point mutations were found in the ERG3 gene sequence of 14 strains of C.albicans,including 24(85.71%)synonymous mutations and 4(14.29%)missense mutations;the synonymous mutation sites were C602 T,T432 C and C438 T,and the missense mutation sites were I340 L,V374 G,P902 L and V1076 A.The high expression rate of ERG3 gene was remarkably higher in the fluconazole-resistant strains than in the fluconazole-sensitive strains.CONCLUSION The C.albicans strains causing IFI show certain resistance to fluconazole,and the drug resistance may be associated with the missense mutations of ERG3 gene I340 L,V374 G,P902 L and V1076 A.