Establishing surrogate markers for fluconazole resistance in Candida albicans.
Azole-resistant Candida can be a confounding factor for clinical management of opportunistic infections in immunocompromised patients, but rapid identification of such resistant organisms can improve patient outcome. New target-based molecular diagnostic strategies have the potential to identify resistant organisms faster than current culture-based assays. It was the objective of this study to determine whether target site mutations and/or drug pump over-expression are suitable surrogate markers of drug resistance that could aid new molecular-based diagnostic assays. A collection of 59 clinical isolates displaying a range of azole susceptibilities were assayed for mutations within the target gene Erg 11 and for over-expression of drug-efflux pumps Cdr 1, Cdr 2, Flu 1, and Mdr 1, as well as drug target gene Erg 11 by quantitative real-time PCR with molecular beacons. A fluconazole-resistant (MIC>or=64 microg/ml) phenotype was closely associated with over-expression of Cdr 1 (p=0.005), Cdr 2 (p=0.01), and Mdr 1 (p=0.03) along with four mutations in Erg 11 (T 229 A, Y 132 F, S 405 F, G 464 S). Changes in expression levels for Erg 11 and Flu 1 were not statistically correlated with resistance (p=0.27 and p=0.86, respectively). Overall, these findings provide a statistical basis to establish Erg 11 mutations and drug pump over-expression as surrogate markers for phenotypic fluconazole resistance.
Park
Steven
S
Public Health Research Institute, Newark, NJ 07103, USA.
Perlin
David S
DS
D000935:Antifungal Agents / Q000494:pharmacology*; D015415:Biomarkers / Q000378:metabolism; D002176:Candida albicans / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D002177:Candidiasis / Q000382:microbiology*; D025141:Drug Resistance, Fungal / Q000235:genetics*; D004875:Ergosterol / Q000096:biosynthesis; D015725:Fluconazole / Q000494:pharmacology*; D005656:Fungal Proteins / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D009154:Mutation / Q000187:drug effects / Q000235:genetics
D000935:Antifungal Agents; D015415:Biomarkers; C094693:CDR1 protein, Candida albicans; D005656:Fungal Proteins; D026901:Membrane Transport Proteins; D015725:Fluconazole; D004875:Ergosterol