Evaluation of the Bruker Biotyper Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry System for Identification of Aspergillus Species Directly from Growth on Solid Agar Media

Ying Li; He Wang; Yu-Pei Zhao; Ying-Chun Xu; Po-Ren Hsueh

doi:10.3389/fmicb.2017.01209

Evaluation of the Bruker Biotyper Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry System for Identification of Aspergillus Species Directly from Growth on Solid Agar Media

Front Microbiol. 2017 Jun 29:8:1209. doi: 10.3389/fmicb.2017.01209. eCollection 2017.

Authors

Ying Li^{1

2}, He Wang^{1

2}, Yu-Pei Zhao³, Ying-Chun Xu^{1

2}, Po-Ren Hsueh⁴

Affiliations

¹ Department of Clinical Laboratory, Peking Union Medical College Hospital, Chinese Academy of Medical SciencesBeijing, China.
² Graduate School, Peking Union Medical College, Chinese Academy of Medical SciencesBeijing, China.
³ Department of General Surgery, Peking Union Medical College Hospital, Chinese Academy of Medical SciencesBeijing, China.
⁴ Departments of Laboratory Medicine and Internal Medicine, National Taiwan University Hospital, National Taiwan University College of MedicineTaipei, Taiwan.

Abstract

We evaluated the accuracy of the Bruker Biotyper matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) system at identifying clinical isolates of Aspergillus species that were grown on agar media. A total of 381 non-duplicate Aspergillus isolates representing 21 different Aspergillus species identified by molecular analysis were included in this study. The Bruker Biotyper MALDI-TOF MS system was able to identify 30.2% (115/381) of the isolates to the species level (score values of ≥2.000) and 49.3% to the genus level (score values of 1.700-1.999). When the identification cutoff value was lowered from ≥2.000 to ≥1.700, the species-level identification rate increased to 79.5% with a slight rise of false identification from 2.6 to 5.0%. From another aspect, a correct species-level identification rate of 89% could be reached by the Bruker Biotyper MALDI-TOF MS system regardless of the score values obtained. The Bruker Biotyper MALDI-TOF MS system had a moderate performance in identification of Aspergillus directly inoculated on solid agar media. Continued expansion of the Bruker Biotyper MALDI-TOF MS database and adoption of alternative cutoff values for interpretation are required to improve the performance of the system for identifying highly diverse species of clinically encountered Aspergillus isolates.

Keywords: Aspergillus species; Bruker Biotyper MALDI-TOF MS; matrix-assisted laser desorption/ionization time-of-flight mass spectrometry system; sequence analysis; solid agar media.