Objective This study aimed to investigate the molecular mechanisms responsible for fluconazole resistance in clinical isolates of this pathogenic yeast.Methods A total of 41 Candida tropicalis strains were collected f...Objective This study aimed to investigate the molecular mechanisms responsible for fluconazole resistance in clinical isolates of this pathogenic yeast.Methods A total of 41 Candida tropicalis strains were collected from the clinical laboratory of Taiyuan City Central Hospital.Antifungal susceptibility testing was performed by ATB FUNGU 3 method.The 14 α-demethylase (ERG11) gene in all clinical isolates of Candida tropicalis were amplified by PCR,and their nucleotide sequences were determined in order to detect point mutations.Likewise,efflux transporters (CDR1 and MDR1) and ERG11 genes were tested by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) for their expression in Candida tropicalis cells at the mRNA level.Results The fluconazole-resistant rate of 41 Candida tropicalis was 12.2%.The amino acid substitutions in ERG11p of R245K,Y221F and V362I were found in fluconazole-resistant isolates.And no amino acid substitution was detected in fluconazole-susceptible ones.The mRNA level of CDR1,MDR1 and ERG11 genes in fluconazole-resistant isolates all showed overexpression compared with fluconazole-susceptible ones.Conclusions Missense mutations in ERG11 gene associated with overexpression of CDR1,MDR1 and ERG11 gene seemed to be responsible for the acquired fluconazole resistance of these clinical isolates.展开更多
文摘Objective This study aimed to investigate the molecular mechanisms responsible for fluconazole resistance in clinical isolates of this pathogenic yeast.Methods A total of 41 Candida tropicalis strains were collected from the clinical laboratory of Taiyuan City Central Hospital.Antifungal susceptibility testing was performed by ATB FUNGU 3 method.The 14 α-demethylase (ERG11) gene in all clinical isolates of Candida tropicalis were amplified by PCR,and their nucleotide sequences were determined in order to detect point mutations.Likewise,efflux transporters (CDR1 and MDR1) and ERG11 genes were tested by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) for their expression in Candida tropicalis cells at the mRNA level.Results The fluconazole-resistant rate of 41 Candida tropicalis was 12.2%.The amino acid substitutions in ERG11p of R245K,Y221F and V362I were found in fluconazole-resistant isolates.And no amino acid substitution was detected in fluconazole-susceptible ones.The mRNA level of CDR1,MDR1 and ERG11 genes in fluconazole-resistant isolates all showed overexpression compared with fluconazole-susceptible ones.Conclusions Missense mutations in ERG11 gene associated with overexpression of CDR1,MDR1 and ERG11 gene seemed to be responsible for the acquired fluconazole resistance of these clinical isolates.
