부산대학교 도서관

Respiratory specimens obtained from patients with chronic forms of aspergillosis contain phenotypic variants of azole-resistant Aspergillus fumigatus (ARAF) that co-exist in the airway. Here we aimed to study whether phenotypic variants of ARAF that co-exist in clinical specimens were genetically distinct. A panel of six phenotypic variants of ARAF cultured from two sputum samples collected from two patients with chronic aspergillosis were included. Preliminary identification of all isolates was obtained using MALDI-ToF mass spectrometry and confirmed by AsperGenius.sup.® real-time PCR assay. Antifungal susceptibility testing was determined using EUCAST E.Def 9.3 microbroth dilution. Genomic DNA libraries were constructed with the Illumina TruSeq Nano kit. Prepared whole-genome libraries were sequenced on an Illumina HiSeq 2500. Whole genome data were converted into presence/absence of a SNP with respect to the Af293 reference genome. Colonies of ARAF that co-existed in one respiratory sample demonstrated marked phenotypic diversity. Two cyp51A polymorphisms were found among azole-resistant isolates: TR.sub.34/L98H/T289A/I364V/G448S was consistently present in four variants with a pan-azole resistant phenotype and TR.sub.34/L98H was detected in two variants (itraconazole MIC > 16 mg/L). WGS typing showed that despite marked phenotypic variation, each sample contained a population of highly genetically related azole-resistant A. fumigatus variants. Our SNP analysis suggest that mechanisms additional to genetic-based variation are responsible for phenotypic diversity. Our data demonstrate that the phenotypic variants of ARAF that co-exist in clinical specimens are highly clonal and strongly suggest their origination from a single common ancestor.
Author(s): Alireza Abdolrasouli [sup.1] [sup.2], Johanna L. Rhodes [sup.2] Author Affiliations: (1) grid.46699.34, 0000 0004 0391 9020, Department of Medical Microbiology, King's College Hospital, , London, UK (2) grid.7445.2, 0000 [...]