Investigation of the relationship between fluconazole susceptibility, proteinase activity and ERG11-SAP2 Expression in Candida albicans strains isolated from clinical samples.

Background and purpose: Candida albicans is currently recognised as an opportunistic pathogen that can cause many invasive infections. Resistance mechanisms and fungal virulence factors play an important role in the effectiveness of treatment. The aim of this study was to investigate the relationship between fluconazole resistance, proteinase activity and ERG11 (sterol 14-demethylase)- SAP2 (secreted aspartic protease 2) gene expression levels in C.albicans strains.

Materials and methods: Candida albicans strains isolated from patient samples sent to Medical Microbiology laboratory of Düzce University from various clinics were included in the study. Fluconazole susceptibilities of the isolates were determined by broth microdilution method. The increase in fluconazole MIC values at 48 hours and proteinase activities of the isolates were analysed. ERG11 and SAP2 gene expression levels were measured by real time qPCR.

Results: Fluconazole resistance rate was found to be 3.14% in 127 C. albicans strains. A moderate positive correlation was found between ERG11 and SAP2 values (p=0.029, r:0.655, p<0.001). There was no correlation between SAP2/ERG11 expression levels and fluconazole resistance. Proteinase positivity was detected in 81.1%, of 127 strains and no statistically significant correlation was found between proteinase activities and SAP2/ERG11 expression levels. While there was a statistically significant relationship between ERG11 expression levels and 48th hour MIC elevation, there was no statistically significant relationship between SAP2 levels and 48th hour MIC elevation.

Conclusion: In addition to the moderate positive correlation between ERG11 and SAP2 values, a significant correlation was found between ERG11 expression and fluconazole tolerance.