Expression of fluconazole resistance-associated genes in biofilm from 23 clinical isolates of Candida albicans
This study aimed to establish the influence of biofilm from clinical isolates of Candida albicans on fluconazole resistance, focusing on efflux pumps and azole-targeted enzymes. Twenty-three C. albicans clinical isolates were collected from two hospitals in Shanghai, China. Antifungal susceptibility tests were performed on biofilm and planktonic cells. A crystal violet assay was used to monitor biofilm growth. Real-time RT-PCR was performed to quantify the expression of the transporter-related genes MDR1, CDR1, and CDR2 as well as ERG11, a gene encoding an enzyme targeted by antifungal drugs. Fluconazole resistance was shown to increase in biofilm in a time-dependent manner. No significant differences were observed between different strains of C. albicans. Genes encoding efflux pumps were overexpressed in early stages of biofilm formation and could also be induced by fluconazole. While ERG11 was not upregulated in biofilm, it was overexpressed upon the addition of fluconazole to biofilm and planktonic cells. Gene expression also appeared to be related to the original genotype of the strain. The upregulation of genes encoding efflux pumps demonstrates their role in the development of fluconazole resistance during the early stages of C. albicans biofilm formation.
KeywordsCandia albicans Biofilm Fluconazole resistance Efflux pump
We thank our colleagues for their help with collecting the clinical isolates.
This work was supported by grants from the Program of Shanghai Municipal Health Bureau of China (2009239), the Program of Science and Technology Commission of Shanghai Municipality (114119b0500), and the Scientific Research Key Project of Shanghai Municipal Health Bureau (20124005).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflicts of interest.
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