Bruker biotyper matrix-assisted laser desorption ionization-time of flight mass spectrometry system for identification of Nocardia, Rhodococcus, Kocuria, Gordonia, Tsukamurella, and Listeria species.
We evaluated whether the Bruker Biotyper matrix-associated laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) system provides accurate species-level identifications of 147 isolates of aerobically growing Gram-positive rods (GPRs). The bacterial isolates included Nocardia (n = 74), Listeria (n = 39), Kocuria (n = 15), Rhodococcus (n = 10), Gordonia (n = 7), and Tsukamurella (n = 2) species, which had all been identified by conventional methods, molecular methods, or both. In total, 89.7% of Listeria monocytogenes, 80% of Rhodococcus species, 26.7% of Kocuria species, and 14.9% of Nocardia species (n = 11, all N. nova and N. otitidiscaviarum) were correctly identified to the species level (score values, ≥ 2.0). A clustering analysis of spectra generated by the Bruker Biotyper identified six clusters of Nocardia species, i.e., cluster 1 (N. cyriacigeorgica), cluster 2 (N. brasiliensis), cluster 3 (N. farcinica), cluster 4 (N. puris), cluster 5 (N. asiatica), and cluster 6 (N. beijingensis), based on the six peaks generated by ClinProTools with the genetic algorithm, i.e., m/z 2,774.477 (cluster 1), m/z 5,389.792 (cluster 2), m/z 6,505.720 (cluster 3), m/z 5,428.795 (cluster 4), m/z 6,525.326 (cluster 5), and m/z 16,085.216 (cluster 6). Two clusters of L. monocytogenes spectra were also found according to the five peaks, i.e., m/z 5,594.85, m/z 6,184.39, and m/z 11,187.31, for cluster 1 (serotype 1/2a) and m/z 5,601.21 and m/z 11,199.33 for cluster 2 (serotypes 1/2b and 4b). The Bruker Biotyper system was unable to accurately identify Nocardia (except for N. nova and N. otitidiscaviarum), Tsukamurella, or Gordonia species. Continuous expansion of the MALDI-TOF MS databases to include more GPRs is necessary.
Department of Laboratory Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan Department of Internal Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan hsporen@ntu.edu.tw.
Po-Ren
PR
Hsueh
Department of Laboratory Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan Department and Graduate Institute of Clinical Laboratory Sciences and Medical Biotechnology, National Taiwan University, Taipei, Taiwan.
Tai-Fen
TF
Lee
Department of Laboratory Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan.
Shin-Hei
SH
Du
Department of Graduate Institute of Biomedical Sciences, Chang Gung University, Tao-Yuan, Taiwan Bruker Taiwan Co., Ltd., Taipei, Taiwan.
Shih-Hua
SH
Teng
Department of Internal Medicine, Far Eastern Memorial Hospital, Taipei, Taiwan.
Chun-Hsing
CH
Liao
Department of Internal Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan.
Wang-Hui
WH
Sheng
Department of Laboratory Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan Department and Graduate Institute of Clinical Laboratory Sciences and Medical Biotechnology, National Taiwan University, Taipei, Taiwan.
Lee-Jene
LJ
Teng
D000192:Actinomycetales / Q000737:chemistry / Q000145:classification* / Q000302:isolation & purification; D000193:Actinomycetales Infections / Q000175:diagnosis* / Q000382:microbiology; D001420:Bacteria, Aerobic / Q000737:chemistry / Q000145:classification / Q000302:isolation & purification; D001431:Bacteriological Techniques / Q000379:methods*; D016000:Cluster Analysis; D016987:Gram-Positive Rods / Q000737:chemistry / Q000145:classification / Q000302:isolation & purification; D006801:Humans; D008087:Listeria / Q000737:chemistry / Q000145:classification* / Q000302:isolation & purification; D008088:Listeriosis / Q000175:diagnosis* / Q000382:microbiology; D012680:Sensitivity and Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*