Development and Validation of a High-Resolution Melting Assay To Detect Azole Resistance in Aspergillus fumigatus

• Published in: Antimicrobial agents and chemotherapy Vol. 61; no. 12
• Main Authors: Bernal-Martínez, L, Gil, H, Rivero-Menéndez, O, Gago, S, Cuenca-Estrella, M, Mellado, E, Alastruey-Izquierdo, A
• Format: Journal Article
• Language: English
• Published: United States American Society for Microbiology 01.12.2017
• Subjects: Antifungal Agents; Antifungal Agents - pharmacology; Aspergillosis - drug therapy; Aspergillus fumigatus; Aspergillus fumigatus - drug effects; Aspergillus fumigatus - genetics; Cytochrome P-450 Enzyme System; Cytochrome P-450 Enzyme System - genetics; Drug Resistance, Fungal; Drug Resistance, Fungal - genetics; Fungal Proteins; Fungal Proteins - genetics; Humans; Mechanisms of Resistance; Microbial Sensitivity Tests; Nucleic Acid Denaturation - genetics; Polymerase Chain Reaction; Polymerase Chain Reaction - methods; Promoter Regions, Genetic - genetics; Tandem Repeat Sequences - genetics; TR34/L98H; azoles; high-resolution melting; aspergillosis; cyp51A; TR46/Y121F/T289A; Aspergillus fumigatus; antifungal resistance
• ISSN: 0066-4804; 1098-6596
• DOI: 10.1128/aac.01083-17

The global emergence of azole-resistant strains is a growing public health concern. Different patterns of azole resistance are linked to mutations in Therefore, accurate characterization of the mechanisms underlying azole resistance is critical to guide selection of the most appropriate antifungal agent for patients with aspergillosis. This study describes a new sequencing-free molecular screening tool for early detection of the most frequent mutations known to be associated with azole resistance in PCRs targeting mutations at positions G54, Y121, G448, and M220 and targeting different tandem repeats (TRs) in the promoter region were designed. All PCRs were performed simultaneously, using the same cycling conditions. Amplicons were then distinguished using a high-resolution melting assay. For standardization, 30 well-characterized azole-resistant strains were used, yielding melting curve clusters for different resistance mechanisms for each target and allowing detection of the most frequent azole resistance mutations, i.e., G54E, G54V, G54R, G54W, Y121F, M220V, M220I, M220T, M220K, and G448S, and the tandem repeats TR , TR , and TR Validation of the method was performed using a blind panel of 80 azole-susceptible or azole-resistant strains. All strains included in the blind panel were properly classified as susceptible or resistant with the developed method. The implementation of this screening method can reduce the time needed for the detection of azole-resistant isolates and therefore facilitate selection of the best antifungal therapy in patients with aspergillosis.