Objective: To investigate the azole susceptibility of Candida albicans(C.albicans)from vulvovaginal candidosis patients and to analyze the relationship between ERG11 gene mutations in these isolates and azole resistan...Objective: To investigate the azole susceptibility of Candida albicans(C.albicans)from vulvovaginal candidosis patients and to analyze the relationship between ERG11 gene mutations in these isolates and azole resistance.Methods: Three hundred and two clinical isolates of Candida species were collected.Azole susceptibility was tested in vitro in microdilution studies. The ERG11 genes of 17 isolates of C. albicans(2 susceptibles, 5 dose-dependent resistants and 10 resistants) were amplified and sequenced.Results: Of the 302 isolates collected, 70.2% were C. albicans, of which 8.5%, 3.8% and4.2% were resistant to fluconazole, itraconazole and voriconazole, respectively. In total,27 missense mutations were detected in ERG11 genes from resistant/susceptible dosedependent isolates. Among them, Y132 H, A114 S, and Y257 H substitutions were most prevalent and were known to cause fluconazole resistance. G464 S and F72 S also have been proved to cause fluconazole resistance. Two novel substitutions(T285A, S457P) in hotspot regions were identified.Conclusions: Twenty seven mutations in the ERG11 gene were identified in azoleresistant C. albicans isolates, which indicated a possible relation with the increase in resistance to azole drugs and the recurrence of vulvovaginal candidosis. The relationship of two novel substitutions(T285A, S457P) with fluconazole resistance needs to be further verified by site-directed mutagenesis.展开更多
Objective To detect the resistant mechanisms o f Candida albicans to fluconazole (FCZ) at molecular biology lev el, since the resistance me chanisms of azole antifungal agents have been the focus of attention these y...Objective To detect the resistant mechanisms o f Candida albicans to fluconazole (FCZ) at molecular biology lev el, since the resistance me chanisms of azole antifungal agents have been the focus of attention these years . Methods Thirty two FCZ resistant C.albicans were selected as our test strains (MICs≥64?μg/ml). With 14 α demethylase gene (ERG16 ge ne, target enzyme encoding gene of azoles) as our object, we chose six sets of prim ers from the ERG16 gene to amplify the interested fragments, and conducted South ern blot hybridization, restriction fragment length polymorphism (RFLP), and sin gle strand conformation polymorphism (SSCP) analysis for the fragments which wer e amplified by the six sets of primers, and pre resistant sensitive strains wer e used as controls. Three representative fragments, A66, D66 and E78, were selec ted to be cloned and sequenced. Results The polymerase chain reaction (PCR) amplification showed that s everal tested strains were negative for some primers. However, our Southern blot analysis reminded that their resistance did not result from the lack of targ et enzyme coding gene. SSCP analysis s howed that differences were noted between the resistant and sensitive strains an d inter resistant strains. Statistical analysis showed that the most variable s equence lied in the amplifier of the sixth pair of primer, and all the tested 32 strains showed positive results. In the 11 mutation points we found, five resu lted in amino acid alterations. It is likely that one or more mutational alterations (alone or in combination) might lead to the expression of an enzyme highly resi stant to the inhibitory action of FCZ which in turn is responsible for the FCZ r esistant trait in these strains. Conclusion One or more mutational alterations might lead to the azole r esistant trait in this strains.展开更多
基金Supported by the National Natural Science Foundation of China(No.31072125 and 31272549)by a National Science and Technology Project (China) grant (2008ZX-10004-011)
文摘Objective: To investigate the azole susceptibility of Candida albicans(C.albicans)from vulvovaginal candidosis patients and to analyze the relationship between ERG11 gene mutations in these isolates and azole resistance.Methods: Three hundred and two clinical isolates of Candida species were collected.Azole susceptibility was tested in vitro in microdilution studies. The ERG11 genes of 17 isolates of C. albicans(2 susceptibles, 5 dose-dependent resistants and 10 resistants) were amplified and sequenced.Results: Of the 302 isolates collected, 70.2% were C. albicans, of which 8.5%, 3.8% and4.2% were resistant to fluconazole, itraconazole and voriconazole, respectively. In total,27 missense mutations were detected in ERG11 genes from resistant/susceptible dosedependent isolates. Among them, Y132 H, A114 S, and Y257 H substitutions were most prevalent and were known to cause fluconazole resistance. G464 S and F72 S also have been proved to cause fluconazole resistance. Two novel substitutions(T285A, S457P) in hotspot regions were identified.Conclusions: Twenty seven mutations in the ERG11 gene were identified in azoleresistant C. albicans isolates, which indicated a possible relation with the increase in resistance to azole drugs and the recurrence of vulvovaginal candidosis. The relationship of two novel substitutions(T285A, S457P) with fluconazole resistance needs to be further verified by site-directed mutagenesis.
文摘Objective To detect the resistant mechanisms o f Candida albicans to fluconazole (FCZ) at molecular biology lev el, since the resistance me chanisms of azole antifungal agents have been the focus of attention these years . Methods Thirty two FCZ resistant C.albicans were selected as our test strains (MICs≥64?μg/ml). With 14 α demethylase gene (ERG16 ge ne, target enzyme encoding gene of azoles) as our object, we chose six sets of prim ers from the ERG16 gene to amplify the interested fragments, and conducted South ern blot hybridization, restriction fragment length polymorphism (RFLP), and sin gle strand conformation polymorphism (SSCP) analysis for the fragments which wer e amplified by the six sets of primers, and pre resistant sensitive strains wer e used as controls. Three representative fragments, A66, D66 and E78, were selec ted to be cloned and sequenced. Results The polymerase chain reaction (PCR) amplification showed that s everal tested strains were negative for some primers. However, our Southern blot analysis reminded that their resistance did not result from the lack of targ et enzyme coding gene. SSCP analysis s howed that differences were noted between the resistant and sensitive strains an d inter resistant strains. Statistical analysis showed that the most variable s equence lied in the amplifier of the sixth pair of primer, and all the tested 32 strains showed positive results. In the 11 mutation points we found, five resu lted in amino acid alterations. It is likely that one or more mutational alterations (alone or in combination) might lead to the expression of an enzyme highly resi stant to the inhibitory action of FCZ which in turn is responsible for the FCZ r esistant trait in these strains. Conclusion One or more mutational alterations might lead to the azole r esistant trait in this strains.
