[Characterization of azole resistance mechanisms in Chilean clinical isolates of Candida albicans]. / Caracterización de los mecanismos de resistencia a azoles en aislados clínicos chilenos de Candida albicans.

ABSTRACT

INTRODUCTION: The commensal yeast Candida albicans, can cause superficial or systemic candidiasis in susceptible hosts. In Chile, azole antifungals are the most widely used drugs in the treatment of candidiasis. In a previous study performed at our center, 2.1 and 1.6% of clinical isolates of C. albicans were found to be resistant to fluconazole and voriconazole, respectively. OBJECTIVE: To characterize the resistance mechanisms involved in azoles resistance in Chilean clinical isolates. METHODOLOGY: Eight resistant, nine susceptible-dose dependent (SDD) and 10 susceptible strains (n 27) were selected according to the Clinical Laboratory Standards Institute (CLSI) M27-S3 criteria, from vaginal and urine samples. Mutations in the 408-488 region of the ERG11 gene were studied by sequencing, and the relative expression of ERG11 gene and efflux pump genes CDR1, CDR2 and MDR1, was evaluated by quantitative real-time PCR (q-PCR). RESULTS: No mutations were detected in the ERG11 gene and its overexpression was found only in 12.5% of the resistant strains (1/8). The most prevalent mechanism of resistance was the over-expression of efflux pumps (62.5%; 5/8). CONCLUSION: The study of the expression of efflux pumps by q-PCR could be a useful diagnostic tool for early detection of azole resistance in C. albicans.