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Investigation of mutations in ERG11 gene of fluconazole-resistant Candida albicans isolates from Turkish hospitals

Abstract number: O370

Manastir L., Ergon C., Yucesoy M.

Background: Life-threatening Candida infections have become an important clinical problem. Fluconazole is one of the azoles widely used for both prophylaxis and therapy of Candida infections. This widespread and repeated use of fluconazole has resulted in resistance in Candida isolates.

Objectives: The aim of our study was to investigate Y132H and other mutations in the ERG11 gene and to determine the possible contribution of efflux pumps in conferring fluconazole resistance to C. albicans isolates.

Methods: Seven fluconazole-resistant / susceptible dose-dependent (R/SDD) and ten fluconazole-susceptible (S) C. albicans isolates cultured from various clinical specimens were included in this study. The susceptibility of the strains against amphotericin B, fluconazole, itraconazole, ketokonazole, clotrimazole and flucytosine were determined by broth microdiltion method according to CLSI M27-A2 standards. Restriction enzyme analysis was performed by using PagI enzyme after PCR on all isolates for Y132H mutation, and sequence analysis was done for other mutations in the ERG11 gene. Overexpression of efflux pumps was also investigated by microdilution method M27-A2 using substrates and inhibitors.

Results: All seven fluconazole R/SDD isolates were found to be resistant to flucytosine except one, all were susceptible to amphotericin B and all isolates except one were resistant to itraconazole and ketoconazole and all of them except one were susceptible to clotrimazole. Y132H mutation was not detected in all strains. K143R, G464S, G465S and V488I mutations were determined in three of the R/SDD isolates. S412T and R469K mutations determined only in this group of strains by sequence analysis were thought to play a role in resistance but they should be evaluated with advanced studies. Possible overexpression of efflux pumps was determined especially in three fluconazole-resistant C. albicans isolates.

Conclusion: Mutations such as K143R, G464S, G465S and V488I in ERG11 gene and overexpression of efflux pumps were determined to be effective mechanisms in our R/SDD C. albicans isolates; however other mechanisms of resistance, such as overexpression of ERG11 and mutations in the ERG3 gene should also be investigated.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Subject:
Location: Barcelona, Spain
Presentation type:
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