Susceptibility and resistance gene evaluation of Candida albicans clinical isolates obtained from clinical specimen in the Hospital de Clinicas UNICAMP

Abstract

Candida species are members of the normal microbiota of human body. When there is an imbalance in the relationship between microbiota and host, these can become opportunistic pathogens, being C. albicans the most common isolated species. The systemic or visceral candidiasis presents as localized infectious symptoms and can spread to other organs through haematogenic route. The antifungal agent Fluconazole inhibits ergosterol synthesis - essential component of the fungal cell membrane - and is widely used for prophylaxis and treatment of infections caused by Candida species. While some species are genetically resistant (C. krusei) or easily acquire resistance (C. glabrata) to Fluconazole, there are not many reports of resistance in C. albicans. However, C.albicans is able to develop resistance mechanisms to Fluconazole, including mutations in ERG11 gene, which codes for the production of the enzyme that acts in ergosterol biosynthesis. The present study aims to characterize the susceptibility profile of antifungals against blood culture isolates of C. albicans and the investigation of the occurrence of mutations in the ERG11 gene of two in vitro Fluconazole resistant isolates of C. albicans. The in vitro susceptibility to antifungal agents will be performed by broth microdilution method according to the M27A3 and S4 documents (CLSI). Screening for mutations in the ERG11 gene will be performed by amplification of three gene regions, with ERGSec1A/1B , ERGSec2A/2B ERGSec3A/3B primers. The resulting product will be submitted to sequencing and analysis of amplified DNA fragments by comparison to a standard strain sensitive to Fluconazole (C. albicans ATCC 90028). (AU)