Quantification of CDR1 Gene Expression in Fluconazole Resistant Candida Glabrata Strains Using Real-time PCR.

BACKGROUND: The opportunistic fungi, particularly Candida glabrata has been known as main etiologic agents of life-threating infections in some patients. Although fluconazole is the most effective antifungal agent against candidiasis, C. glabrata, fluconazole-resistant strains have been increased recently overexpression or mutations of ATP-binding cassette (ABC) transporter family membrane proteins such as; Cg CDR1, Cg CDR2 are responsible for fluconazole resistance in a large proportion of candidiasis cases. The aim of this study was to evaluate CDR1 gene expression level as one of main mechanism involved in this resistance using. METHODS: Candida glabrata strains were collected from various clinical samples in hospitals of Tehran in 2015 . After validation of all isolates by conventional and molecular methods, the susceptibility analysis to fluconazole of all isolates was performed using CLSI broth microdilution M27-A3 and M27-S4 protocols. Two isolates have been selected based on difference in susceptibility and CDR1-mRNA expression level of isolates was measured by Real-time PCR method. RESULTS: Susceptibility results revealed that 32%, 64% and 4% of strains were susceptible, dose-dependent (DD) and resistant to fluconazole respectively. Furthermore, resistance strain of C. glabrata (MIC≥64 µg/ml) showed overexpression of CDR1 compared with sensitive strain in Real-time PCR analysis. CONCLUSION: Thus, it is necessary to investigate the functions of CgCDR1 genes as a transporter-related gene.

In Vitro Antifungal Susceptibility Profiles of Candida albicans Complex Isolated from Patients with Respiratory Infections.

Candidiasis, the main opportunistic fungal infection has been increased over the past decades. This study aimed to characterize C.albicans species complex (C.albicans, C.dubliniensis, and C.africana) isolated from patients with respiratory infections by molecular tools and in vitro antifungal susceptibilities by using broth microdilution method according to CLSI M27-A3 guidelines. Totally, 121 respiratory samples were collected from patients with respiratory infections. Of these, 83 strains were germ tube positive and green colonies on chromogenic media, so initially identified as C.albicans species complex and subsequently were classified as C.albicans (89.15%), C.dubliniensis (9.63%), and C.africana (1.2%) based on PCR-RFLP and amplification of hwp1 gene. Minimum inhibitory concentration (MICs) results showed that all tested isolates of C.albicans complex were highly susceptible to triazole drugs. However, caspofungin had highest activity against C.albicans, C.dubliniensis, and C.africana. Our findings indicated the variety of antifungal resistance of Candida strains in different areas. These results may increase the knowledge about the local distribution of the mentioned strains as well as their antifungal susceptibility pattern which play an important role in appropriate therapy.