1887

Abstract

Antifungal drug resistance in the pathogenic fungus is a serious threat to the growing population of immunocompromised patients. This study describes a significant correlation between loss of heterozygosity at the mating-type-like () locus and resistance to azole antifungals. A pool of 96 clinical isolates consisting of 50 azole-resistant or susceptible dose-dependent isolates and 46 azole-susceptible isolates was screened by PCR for the presence of and α. These genes were used as markers for the and MTLα loci. Both loci were present in 84 of the isolates. Six isolates failed to amplify and six failed to amplify α. Further PCR analysis demonstrated that loss of the and α genes corresponded to loss of all of the loci-specific genes, resulting in homozygosity at the locus. Southern analysis and single nucleotide polymorphism (SNP) analysis were used to determine that this loss of heterogeneity was due to replacement of one of the loci with a duplicate of the other locus resulting in two homozygous copies of the locus. Of the 12 homozygous isolates, one isolate was sensitive to azole drugs. Statistical analysis of the data demonstrates a strong correlation between homozygosity at the locus and azole resistance (<0003). In a set of serial isolates, an increase in azole resistance correlated with the loss of heterozygosity at the locus, lending further strength to the correlation. Gene disruptions of the loci were found to have no effect on azole susceptibility.

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2002-04-01
2020-03-31
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