Mechanisms of azole resistance in Candida albicans clinical isolates from Shanghai, China.
This study was undertaken to characterize the mechanism(s) of azole resistance in clinical isolates of Candida albicans collected in Shanghai, China, focusing on the role of efflux pumps, target enzymes of fluconazole (Erg11), respiratory status and the ergosterol biosynthetic pathway. Clinical isolates of C. albicans (n = 30) were collected from 30 different non-HIV-infected patients in four hospitals in Shanghai. All 30 C. albicans isolates were susceptible to amphotericin B and 5-fluorocytosine. Twelve C. albicans isolates showed resistance to at least one type of triazole antifungal. Flow cytometry analysis of rhodamine 6G efflux showed that azole-resistant isolates had greater efflux pump activity, which was consistent with elevated levels of CDR1 and CDR2 genes that code for ABC efflux pumps. However, we did not observe increased expression of ERG11 and MDR1 or respiratory deficiency. Several mutations of ERG11 and TAC1 genes were detected. The F964Y mutation in the TAC1 gene was identified for the first time. Two main sterols, ergosterol and lanosterol, were identified by GC-MS chromatogram, and no missense mutations were found in ERG3. Furthermore, seven amino acid substitutions in ERG11, A114S, Y132H, Y132F, K143Q, K143R, Y257H and G448E were found, by Type II spectral quantitative analysis, to contribute to low affinity binding between Erg11 and fluconazole.
Department of Laboratory Medicine, Ruijin Hospital Luwan Branch, Shanghai Jiao Tong University School of Medicine, No. 149 South Chongqing Road, Shanghai 200020, China.
Jin-Yan
JY
Liu
Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Ce
C
Shi
Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Ying
Y
Wang
Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Wen-Jing
WJ
Li
Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Yue
Y
Zhao
Department of Laboratory Medicine, Ruijin Hospital Luwan Branch, Shanghai Jiao Tong University School of Medicine, No. 149 South Chongqing Road, Shanghai 200020, China; Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China. Electronic address: mjxiang123456@126.com.
Ming-Jie
MJ
Xiang
D019943:Amino Acid Substitution; D000935:Antifungal Agents / Q000494:pharmacology*; D001393:Azoles / Q000493:pharmacokinetics*; D002176:Candida albicans / Q000187:drug effects* / Q000235:genetics*; D002681:China; D025141:Drug Resistance, Fungal / Q000235:genetics; D004875:Ergosterol / Q000032:analysis / Q000302:isolation & purification; D005434:Flow Cytometry; D015725:Fluconazole / Q000378:metabolism / Q000494:pharmacology*; D005800:Genes, Fungal; D019450:Genes, MDR; D006801:Humans; D007810:Lanosterol / Q000032:analysis / Q000302:isolation & purification; D020125:Mutation, Missense; D060888:Real-Time Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
D000935:Antifungal Agents; D001393:Azoles; D007810:Lanosterol; D015725:Fluconazole; D004875:Ergosterol
Biosynthetic pathway; ERG11; Efflux pumps; Ergosterol; Transcription factor; Triazole resistance