Application of real-time quantitative PCR to molecular analysis of Candida albicans strains exhibiting reduced susceptibility to azoles.

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Chau AS, Mendrick CA, Sabatelli FJ, Loebenberg D, McNicholas PM

Application of real-time quantitative PCR to molecular analysis of Candida albicans strains exhibiting reduced susceptibility to azoles.

Antimicrob Agents Chemother. 2004 Jun;48(6):2124-31.

PubMed ID

15155210 [ View in PubMed

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Abstract

Real-time quantitative PCR was used to measure expression levels of genes encoding efflux pumps, ERG11 and two control genes, ACT1 and PMA1, in a collection of 14 fluconazole-susceptible Candida albicans isolates. For each gene, average expression levels and variations within the population were determined. These values were then used as reference points to make predictions about the molecular basis of resistance in 38 clinical isolates (the majority of which were resistant to fluconazole) obtained from 18 patients treated with posaconazole for refractory oropharyngeal candidiasis. For each of the 38 isolates, the expression levels of genes encoding efflux pumps, ERG11 and the control genes, were measured as above. Comparison of the two data sets revealed that expression of ACT1 and PMA1 did not vary significantly between the two sets of isolates. In contrast, MDR1, ERG11, CDR1, and CDR2 were overexpressed in 3, 4, 14, and 35, respectively, of the isolates from patients treated with azoles. In addition to these changes, the patient isolates all had at least one and often multiple missense mutations in ERG11. Select ERG11 alleles were expressed in Saccharomyces cerevisiae; all of the alleles tested conferred reduced susceptibility to fluconazole. Despite both the increases in pump expression and the ERG11 mutations, only one of the patient isolates exhibited a large decrease in posaconazole susceptibility.

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Posaconazole	Cytochrome P450 51	Protein	Yeast	Yes	Antagonist	Details