Panfungal PCR assays using fresh frozen paraffin embedded tissue specimens for fungal species identification and the detection of azole-resistance mutations in the A. fumigatus cyp51A gene at a South Korean hospital
Background: With rising concerns about changing fungal epidemiology and azole resistance in Aspergillus species, identifying fungal species and susceptibility patterns of mucorales and aspergillosis are crucial in the management of these diseases. The objectives of this study were to evaluate performance of panfungal PCR assays on formalin-fixed paraffin embedded (FFPE) samples for fungal species identification, and the detection of azole-resistance mutations in the Aspergillus fumigatus (
... us fumigatus ( A.fumigatus ) cyp51A gene at a South Korean hospital. Methods: A total of 75 FFPE specimens with a histopathological diagnosis of aspergillosis or mucormycosis were identified during the 10-year study period (2006-2015). After deparaffinization and DNA extraction, panfungal PCR assays were conducted on FFPE samples for fungal species identification. The identified fungal species were compared with histopathological diagnosis. On samples identified as A.fumigatus , sequencings to identify frequent mutations in the cyp51A gene (tandem repeat 46 [TR46], L98H, and M220 alterations) that confer azole resistance were performed. Results: Specific fungal DNA was identified in 31 (41.3%) FFPE samples, and of these, 16 samples of specific fungal DNA were in accord with histopathological diagnosis of aspergillosis or mucormycosis. 15 samples had discordant histopathology and PCR results. No azole-mediating cyp51A gene mutation was revealed among nine cases of A. fumigatus . Moreover, no cyp51A mutations were identified among three cases with history of prior azole use. Conclusion: The pan-fungal PCR assay with FFPE sample may provide additional information on fungal species identification. No azole-resistance mediating mutations in the A. fumigatus cyp51A gene were identified among FFPE samples during study period.