热带假丝酵母菌对氟康唑耐药性分析

Mechanism of fluconazole resistance of Candida tropicalis in clinical isolates

目的研究热带假丝酵母菌分离株对氟康唑的耐药性,并探讨其耐药的分子机制。方法检测142株热带假丝酵母菌对氟康唑药物的敏感性,PCR扩增热带假丝酵母菌ERG11全基因序列,DNA测序后经生物信息学分析CtERG11基因突变。结果142株热带假丝酵母菌中,128株对氟康唑敏感,占90.1%;4株为氟康唑剂量依赖(S-DD)株,占2.8%;10株对氟康唑耐药,占7.1%;CtERG11序列分析发现,氟康唑敏感株中未见基因突变;S-DD株中出现G1362A和C1404T沉默突变;耐药株中共出现T225C、A242C、T243C、G264A、A395T、C461T和G1362A等7种点突变,并导致D81A、Y132F和S154F氨基酸突变。结论D81A、Y132F和S154F氨基酸突变可能与热带假丝酵母菌对氟康唑耐药有关。

Objective To investigate fluconazole resistance of Candida tropicalis and its molecular mechanism.Methods One hundred and forty-two clinical isolates of Candida tropicalis were collected.Fluconazole susceptibility was tested in vitro with broth microdilution method M27-A2.The CtERG11 genes of Candida tropicalis were amplified and sequenced.Results Of the 142 isolates collected,128（90.1%） were susceptible to fluconazloe,4（2.8%） were susceptible dose-dependent（S-DD） and 10（7.1%） were fluconazole-resistant.The CtERG11 gene sequences of Candida tropicalis isolates were compared with that of Candida tropicalis ATCC 750 and the fluconazole-susceptible strains were completely identical with Candida tropicalis ATCC 750.Two silent mutations of G1362A and C1404T were detected in the fluconzaloe S-DD strains;seven nucleotide substitutions of T225C,A242C,T243C,G264A,A395T,C461T and G1362A were found in the four fluconazole-resistant isolates,which resulted in missense mutations of D81A,Y132F and S154F.The nucleotide substitutions of A242C,T243C,G1362A and C1404T were detected and D81A was a novel amino mutation.Conclusion The fluconazole-resistant rate of Candida tropicalis is 7.1% and the missense mutations of D81A,Y132F,and S154F in CtERG11 gene seem to be associated with the fluconazloe resistance of Candida tropicalis.