Low frequency of itraconazole resistance found among Aspergillus fumigatus originating from poultry farms in Southwest Poland

Abstract

Aim: The aim of this study was to investigate the collection of avian Aspergillus fumigatus isolates for the presence of triazole resistance.

Material and method: The study was performed on 60 A. fumigatus isolates cultured from lung tissue samples from chicken (25), geese (17), turkeys (13) and ducks (5). The samples were obtained from 40 different farms located in the Southwest Poland and were collected in the period of September 2015 to November 2016. The EUCAST microdilution method, with the use of three concentrations of itraconazole (ITR) (1, 0.5, and 0.25mg/L), was used to screen the susceptibility of all isolates. Additionally, the selected 20 isolates were tested with eleven concentrations ranging 0.015-16mg/L of ITR, voriconazole, posaconazole and isavuconazole.

Results: Most tested isolates (59/60) were susceptible to ITR (MIC≤0.5mg/L). One isolate showed elevated MIC for ITR (16mg/L), as well as voriconazole (4mg/L), izavuconazole (4mg/L), and posaconazole (0.5mg/L). This isolate was identified on the basis of DNA analysis as A. fumigatus carrying TR34/L98H mutation. All of the ITR-susceptible isolates under study were also susceptible to other triazoles.

Conclusion: Obtained results indicated a low frequency (1.6%) of A. fumigatus resistant to triazoles among avian isolates from the Southwest regions of Poland.

Keywords: Aspergillosis; Aspergillus fumigatus; Domesticated birds; Resistance to triazoles.