Novel point mutations in the ERG11 gene in clinical isolates of azole resistant Candida species.

Danielly Beraldo Dos Santos Silva,Alexéia Barufatti Grisolia/,Adriana Araújo De Almeida,Kelly Mari Pires De Oliveira,Luana Mireli Carbonera Rodrigues

doi:10.1590/0074-02760150400

Abstract

The azoles are the class of medications most commonly used to fight infections caused by Candida sp. Typically, resistance can be attributed to mutations in ERG11 gene (CYP51) which encodes the cytochrome P450 14α-demethylase, the primary target for the activity of azoles. The objective of this study was to identify mutations in the coding region of theERG11 gene in clinical isolates of Candidaspecies known to be resistant to azoles. We identified three new synonymous mutations in the ERG11 gene in the isolates of Candida glabrata (C108G, C423T and A1581G) and two new nonsynonymous mutations in the isolates of Candida krusei - A497C (Y166S) and G1570A (G524R). The functional consequence of these nonsynonymous mutations was predicted using evolutionary conservation scores. The G524R mutation did not have effect on 14α-demethylase functionality, while the Y166S mutation was found to affect the enzyme. This observation suggests a possible link between the mutation and dose-dependent sensitivity to voriconazole in the clinical isolate of C. krusei. Although the presence of the Y166S in phenotype of reduced azole sensitivity observed in isolate C. kruseidemands investigation, it might contribute to the search of new therapeutic agents against resistant Candida isolates.

Highlights

In Latin American countries, Brazil, Candida tropicalis is responsible for 20-24% of all haematogenous infections (Nucci & Colombo 2007, Pfaller & Diekema 2007)
Several mutations are clustered into three hot spot regions in ERG11 gene ranging from amino acids 105165, 266-287, and-488 from Candida albicans, those regions were associated which Candida species resistant to azoles (Marichal et al 1999, Perea et al 2001, Chau et al 2004, Vandeputte et al 2005, Morio et al 2010, Flowers et al 2015, Grossman et al 2015, Tan et al 2015)
Carvalho et al (2013), when investigating mutations on the ERG11 gene in clinical isolates of C. albicans, C. glabrata, and C. tropicalis previously evaluated by fluconazole-susceptibility tests, have identified 14 different missense mutations, five of which had not been previously described, being that one new L321F mutation was identified in C. albicans resistant to fluconazole

Summary

Introduction

In Latin American countries, Brazil, Candida tropicalis is responsible for 20-24% of all haematogenous infections (Nucci & Colombo 2007, Pfaller & Diekema 2007). It is most commonly seen in patients with neutropenia, diabetes mellitus, and in elderly patients (Sipsas et al 2009). The search for mutations in the ERG11 gene in clinically relevant Candida species can provide a better understanding of the molecular mechanisms involved in resistance to antifungal agents and aid in epidemiological research. The objective was to identify mutations in the coding region of the ERG11 gene in clinical isolates of Candida species known to be resistant to azoles

Objectives

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Results

Conclusion