Project description:Azole resistance was induced in vitro by growth of a susceptible C. parapsilosis isolate in the presence of voriconazole. Whole genome microarrays were used to compare the transcriptional response of the voriconizole-resistant and susceptible isolates.
Project description:Azole resistance was induced in vitro by growth of a susceptible C. parapsilosis isolate in the presence of posaconazole. Whole genome microarrays were used to compare the transcriptional response of the posaconazole-resistant and susceptible isolates.
Project description:Azole resistance was induced in vitro by growth of a susceptible C. parapsilosis isolate in the presence of fluconazole. Whole genome microarrays were used to compare the transcriptional response of the fluconazole-resistant and susceptible isolates.
Project description:The present study describes a novel mechanism of antifungal resistance affecting the susceptibility of both the azole and echinocandin antifungals in an azole-resistant isolate from a matched pair of C. parapsilosis isolates obtained from a patient with prosthetic valve endocarditis. Transcriptome analysis indicated differential expression of several genes in the resistant isolate including upregulation of ERG1, ERG2, ERG5, ERG6, ERG11, ERG24, ERG25, ERG27, DAP1 and UPC2, of the ergosterol biosynthesis pathway. Whole genome sequencing revealed a mutation in the ERG3 gene leading to a G111R amino acid substitution in the resistant isolate. Subsequent introduction of this allele in the native ERG3 locus in the susceptible isolate resulted in a fluconazole MIC of >64 mg/ml and a caspofungin MIC of 8 mg/ml. Corresponding allelic replacement of the wildtype allele for the mutant allele in the resistant isolate resulted in a drop in MIC to 1 mg/ml for both fluconazole and caspofungin. Sterol profiles indicated a loss of sterol demethylase activity as a result of this mutation. This work demonstrate that this G111R mutation is wholly responsible for the resistant phenotype in the C. parapsilosis resistant isolate and is the first report of this multidrug resistance mechanism.
