Molecular mechanisms of azole resistance in Candida tropicalis isolates causing invasive candidiasis in China.
Clin Microbiol Infect
; 25(7): 885-891, 2019 Jul.
Article
en En
| MEDLINE
| ID: mdl-30472420
ABSTRACT
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 G464S (<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.Palabras clave
Texto completo:
1
Banco de datos:
MEDLINE
Asunto principal:
Azoles
/
Farmacorresistencia Fúngica
/
Candida tropicalis
/
Candidiasis Invasiva
/
Antifúngicos
Límite:
Humans
País como asunto:
Asia
Idioma:
En
Año:
2019
Tipo del documento:
Article