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Development and multicentre validation of an agar-based screening method for echinocandin susceptibility testing of Aspergillus species

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

DOI

  • Joseph Meletiadis
  • Maria Siopi
  • Lamprini Kanioura
  • Karin Meinike Jørgensen
  • David S Perlin
  • Johan W Mouton
  • Maiken Cavling Arendrup
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BACKGROUND: Reference antifungal susceptibility testing of echinocandins against Aspergillus spp. relies on the determination of the minimal effective concentration, which is difficult to perform, time-consuming and subjective. We developed and evaluated in a multicentre study an agar-based screening method for echinocandin susceptibility testing of Aspergillus spp.

METHODS: Forty WT isolates [10 Aspergillus fumigatus species complex (SC), 10 Aspergillus flavus SC, 10 Aspergillus terreus SC and 10 Aspergillus niger SC] and 4 non-WT A. fumigatus isolates with or without known fks alterations were used. The optimal test conditions and stability over time were evaluated in preliminary studies monitoring colony growth. Twenty-microlitre aliquots of 1-2 McFarland inocula in 0.1% Tween 20 aqueous solution were added to each well and plates were incubated for 24/48 h at 35 ± 2°C. Subsequently, all isolates were tested blindly at three centres using four-well screening plates, containing anidulafungin, caspofungin, micafungin or no antifungal in each of the four wells, respectively.

RESULTS: WT isolates produced fluffy colonies on drug-free agar wells only. The non-WT isolates produced fluffy colonies on echinocandin-containing and control agar wells. Using the echinocandin concentrations of 0.25 mg/L anidulafungin, 1 mg/L caspofungin and 0.125 mg/L micafungin, and the compact (non-fluffy) versus fluffy colony morphology endpoint, all centres successfully discriminated non-WT and WT strains even after 24 h. Among the three echinocandins, anidulafungin produced the clearest endpoints.

CONCLUSIONS: The four-well plate agar method is suitable for echinocandin susceptibility screening of Aspergillus spp. and can be used to detect echinocandin non-WT isolates.

OriginalsprogEngelsk
TidsskriftThe Journal of antimicrobial chemotherapy
Vol/bind74
Udgave nummer8
Sider (fra-til)2247-2254
Antal sider8
ISSN0305-7453
DOI
StatusUdgivet - 1 aug. 2019

Bibliografisk note

© The Author(s) 2019. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For permissions, please email: journals.permissions@oup.com.

ID: 59157236