Up-regulation of CDR1 and MDR1 efflux pump genes and fluconazole resistance are involved in recurrence in Candida albicans-induced vulvovaginal candidiasis.

Recurrent vulvovaginal candidiasis (RVVC) due to fluconazole resistance in Candida albicans isolates causes a wide range of complications. A number of 63 Candida albicans isolates obtained from vulvovaginal candidiasis (VVC) were identified by Internal Transcribed Spacer-Restriction Fragment Length Polymorphism (ITS-RFLP). Antifungal susceptibility testing was performed by broth microdilution method according to the CLSI protocol. The role of CDR1 and MDR1 genes in progress of VVC to RVVC was examined and the activity of virulence-related enzymes was assessed. Candida albicans was diagnosed in 62.4 % cases, of which 22.2 % were confirmed as RVVC. Voriconazole was the most active drug among five tested antifungals. The mean expression level of CDR1 and MDR1 was higher in RVVC isolates compared to multidrug azole-resistant VVC isolates. Our results demonstrated that the expression of CDR1 and MDR1 and the level of phospholipase and proteinase activities could be quite important to induce fluconazole resistance in C. albicans and to progress of VVC to become RVVC in involved patients.

Molecular epidemiology, antifungal susceptibility, and ERG11 gene mutation of Candida species isolated from vulvovaginal candidiasis: Comparison between recurrent and non-recurrent infections.

Vulvovaginal candidiasis (VVC) is a prevalent infection of the genitourinary tract affecting millions of women worldwide. In the present study, the importance of virulence factors, ERG11 gene mutations, ERG11 gene expression, and plasma membrane ergosterol content for fluconazole resistance in Candida species was investigated in 200 women suspected of vulvovaginitis. Isolated Candida species were identified using the ITS-restriction fragment length polymorphism (ITS-RFLP) technique. Antifungal susceptibility testing was performed according to the CLSI document. ERG11 gene expression was analyzed using real-time PCR. ERG11 gene mutation analysis was performed using sequencing methods, and the ergosterol content of the cell membrane was determined in fluconazole-resistant isolates. Furthermore, the production of phospholipase and proteinase enzymes was evaluated in recurrent and non-recurrent infections. VVC was diagnosed in 101 (50.5%) of the 200 clinical cases, of which 21 (20.8%) were confirmed as RVVC. Candida albicans was the most prevalent species, followed by C. glabrata, C. tropicalis, C. krusei, C. parapsilosis, and C. guilliermondii. Ketoconazole and fluconazole were the most effective drugs against C. albicans among five tested antifungals with MIC ranges between 0.06 and 16 µg/mL and 0.25-64 µg/mL. Substitutions of A114S, Y257H, T123I and A114V were detected in fluconazole-resistant C. albicans. The ergosterol content of the fungal cell membrane and the mean levels of ERG11 gene expression transcript were higher in fluconazole-resistant C. albicans isolates obtained from RVVC than in those obtained from VVC cases. Phospholipase and proteinase were produced in different amounts in all Candida species isolated from VVC and RVVC cases. In this review, our results demonstrated that several molecular mechanisms, including ERG11 gene expression, changes in the cell membrane ergosterol content, and mutations in ERG11 gene alone or simultaneously involved in fluconazole resistance of C. albicans species and the recurrence of VVC.