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Open Access Research article

Overexpression of aldo-keto-reductase in azole-resistant clinical isolates of Candida glabrata determined by cDNA-AFLP

Shirin Farahyar1, Farideh Zaini1*, Parivash Kordbacheh1, Sassan Rezaie1, Mahin Safara1, Reza Raoofian3 and Mansour Heidari2

Author Affiliations

1 Department of Medical Mycology and Parasitology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran

2 Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran

3 Department of Medical Genetics, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran

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DARU Journal of Pharmaceutical Sciences 2013, 21:1  doi:10.1186/2008-2231-21-1

Published: 2 January 2013

Abstract

Background

Candida glabrata causes significant medical problems in immunocompromised patients. Many strains of this yeast are intrinsically resistant to azole antifungal agents, and treatment is problematic, leading to high morbidity and mortality rates in immunosuppressed individuals. The primary goal of this study was to investigate the genes involved in the drug resistance of clinical isolates of C. glabrata.

Methods

The clinical isolates of C. glabrata were collected in an epidemiological survey of candidal infection in immunocompromised patients and consisted of four fluconazole and itraconazole resistant isolates, two fluconazole and itraconazole sensitive isolates, and C. glabrata CBS 138 as reference strain. Antifungal susceptibility patterns of the organisms were determined beforehand by the Clinical and Laboratory Standards Institute (CLSI). The potential gene(s) implicated in antifungal resistance were investigated using complementary DNA- Amplified Fragment Length Polymorphism (cDNA-AFLP). Semi-quantitative RT-PCR was carried out to evaluate the expression of gene(s) in resistant isolates as compared to sensitive and reference strains.

Results and conclusions

The aldo-keto-reductase superfamily (AKR gene) was upregulated in the resistant clinical isolates as assessed by cDNA-AFLP. Semi-quantitative RT-PCR revealed AKR mRNA expression approximately twice that seen in the sensitive isolates. Overexpression of the AKR gene was associated with increased fluconazole and itraconazole resistance in C. glabrata. The data suggest that upregulation of the AKR gene might give a new insight into the mechanism of azole resistance.

Keywords:
Azole; Aldo-keto-reductase; cDNA-AFLP; Candida glabrata; Semi-quantitative RT-PCR