This study aimed to describe the phenotypes of Aspergillus flavus when exposed in vitro to caspofungin, and to test whether they were associated to particular microsatellite genotype. The caspofungin MICs of 37 Aspergillus flavus clinical isolates collected from13 patients with invasive aspergillosis where determined using the Etest assay. Molecular typing of A. flavus isolates was done using 12 polymorphic microsatellite markers. The caspofungin MICs ranged from 0.012 to 0.064 mg/L; modal MIC was 0.023 mg/L; the MIC50 and MIC90 where 0.032 and 0.064 mg/L, respectively. A clear end point was noted in 24 (65%) isolates, whereas 7 (19%) displayed a trailing effect and 6 (16%) a paradoxical growth when exposed to caspofungin. The pairwise Fst value was 0.032 (P>0,05), indicating the absence of population structure associated with in vitro paradoxical or trailing growth when exposed to caspofungin. In these Aspergillus flavus isolates, the absence of significant genetic differentiation indicated that trailing or paradoxical growth phenotypes were independent from microsatellite genotype and argues against the hypothesis that they are controlled by a simple genetic mechanism.
Full conference title:
- ISHAM 19th (2015)