4.7 Article

Molecular mechanisms of azole resistance in Candida tropicalis isolates causing invasive candidiasis in China

Journal

CLINICAL MICROBIOLOGY AND INFECTION
Volume 25, Issue 7, Pages 885-891

Publisher

ELSEVIER SCI LTD
DOI: 10.1016/j.cmi.2018.11.007

Keywords

Azole resistance; Candida tropicalis; ERG11; CDR1; MDR1; CYTb; China

Funding

  1. Natural Science Foundation of China [81802042]
  2. PUMCH Out-standing Young Talents Programme [JQ201703]
  3. CAMS Innovation Fund for Medical Sciences [2016-I2M-1-014]

Ask authors/readers for more resources

Objective: We investigated molecular mechanisms responsible for azole resistance in Candida tropicalis isolates. Methods: We studied 507 C. tropicalis isolates causing invasive candidiasis from ten hospitals over 5 years. Antifungal susceptibility was determined by broth microdilution methods. Point mutations in the C. tropicalis ERG11 gene that may confer azole resistance were explored and verified. The expression levels of ERG11, CYTb, MDR1 and CDR1 genes were compared in 20 fluconazole-susceptible and 20 fluconazole-resistant isolates. Results: Fluconazole-susceptible, -susceptible dose-dependent and -resistant strains accounted for 76.7% (389/507), 10.5% (53/507) and 12.8% (65/507) of C. tropicalis isolates, respectively. The ERG11 mutation A395T/W occurred in 10.7% (54/507) of isolates, all of which were resistant to fluconazole. The nucleotide mutation C461T/Y was the second most common (50/507 isolates, 9.9%), and all isolates carrying C461T/Y also had the mutation A395T/W. However, the presence of C461T did not contribute to the azole-resistant phenotype. Substitutions V125A, Y257H and G4645 (<2% of isolates), which were reported for the first time in C tropicalis, also conferred fluconazole non-susceptible phenotypes. Compared with fluconazole susceptible isolates, fluconazole-resistant isolates had higher ERG11 (fold expression level 1.42 versus 0.79, p < 0.01) but lower CYTb (fold expression level 1.26 versus 2.67, p < 0.01) gene expression levels. Three azole-resistant isolates carrying the wild-type ERG11 gene had higher levels of CDR1 and MDR1 expression. Conclusions: ERG11 missense mutations were the major mechanism responsible for azole resistance in C. tropicalis isolates, but overexpression of ERG11, CDR1 and MDR1, as well as reduced expression of CYTb, also contributed to resistance. (C) 2018 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Authors

I am an author on this paper
Click your name to claim this paper and add it to your profile.

Reviews

Primary Rating

4.7
Not enough ratings

Secondary Ratings

Novelty
-
Significance
-
Scientific rigor
-
Rate this paper

Recommended

No Data Available
No Data Available