Candida parapsilosis is an emerging fungal pathogen and a leading cause of hospital-acquired bloodstream fungal infections. The prophylactic and long-term use of fluconazole, a widely used antifungal, has resulted in an increased prevalence of resistance in this pathogen. To understand how C. parapsilosis escapes the effects of fluconazole, we obtained two sets of matched fluconazole-susceptible and -resistant clinical isolates, Clinical Isolate Set 1 and Clinical Isolate Set 2, and have characterized their differential gene expression using a novel whole genome-wide expression technique, RNA-seq, and real-time RT-PCR. Clinical Isolate Set 1 shows significant upregulation of genes encoding major facilitator transporters that are known to efflux drugs out of the cell, and genes involved in response to chemical stimuli. However, we were unable to identify any mutations that would point to a specific mechanism of resistance. RNA-seq and real-time RT-PCR analyses of Clinical Isolate Set 2 shows upregulation of enzymes in the ergosterol biosynthetic pathway that contains the target of fluconazole. After sequencing genes in this pathway that are involved in fluconazole resistance in other species of Candida, we identified a nonsense mutation in ERG3. This mutation has been described in other fluconazole-resistant isolates of Candida species but never before in C. parapsilosis. Furthermore, we have identified what appear to be two distinct modes of fluconazole resistance in two different sets of clinical isolates. This knowledge will contribute to future pharmacological strategies to maintain the efficacy of fluconazole.
|Commitee:||Caudle, Kelly, Gudelsky, Gary, Healy, Daniel, Pauletti, Giovanni|
|School:||University of Cincinnati|
|School Location:||United States -- Ohio|
|Source:||MAI 52/04M(E), Masters Abstracts International|
|Subjects:||Molecular biology, Pharmacy sciences|
|Keywords:||Antifungal resistance, Candida parapsilosis, Fluconazole resistance, Nonsense mutation|
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