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J Clin Microbiol. 2017 Jul;55(7):2030-2034. doi: 10.1128/JCM.00254-17. Epub 2017 Apr 12.

Antifungal Susceptibility Testing of Aspergillus spp. by Using a Composite Correlation Index (CCI)-Based Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry Method Appears To Not Offer Benefit over Traditional Broth Microdilution Testing.

Author information

1
Multi-Organ Transplant Unit, University Health Network, Toronto, ON, Canada.
2
Public Health Ontario, Toronto, ON, Canada.
3
Division of Infectious Diseases, Department of Medicine, University of Toronto, Toronto, ON, Canada.
4
Public Health Ontario, Toronto, ON, Canada julianne.kus@oahpp.ca.
5
Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada.

Abstract

Aspergillus spp. cause serious invasive lung infections, and Aspergillus fumigatus is the most commonly encountered clinically significant species. Voriconazole is considered to be the drug of choice for treating A. fumigatus infections; however, rising resistance rates have been reported. We evaluated a matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS)-based method for the differentiation between wild-type and non-wild-type isolates of 20 Aspergillus spp. (including 2 isolates of Aspergillus ustus and 1 of Aspergillus calidoustus that were used as controls due their intrinsic low azole susceptibility with respect to the in vitro response to voriconazole). At 30 and 48 h of incubation, there was complete agreement between Cyp51A sequence analysis, broth microdilution, and MALDI-TOF MS classification of isolates as wild type or non-wild type. In this proof-of-concept study, we demonstrated that MALDI-TOF MS can be used to accurately detect A. fumigatus strains with reduced voriconazole susceptibility. However, rather than proving to be a rapid and simple method for antifungal susceptibility testing, this particular MS-based method showed no benefit over conventional testing methods.

KEYWORDS:

Aspergillus; MALDI-TOF MS; antifungal susceptibility testing; composite correlation index; voriconazole; voriconazole resistance

PMID:
28404678
PMCID:
PMC5483904
DOI:
10.1128/JCM.00254-17
[Indexed for MEDLINE]
Free PMC Article

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