Using Matrix-Assisted Laser Desorption Ionization-Time of Flight (MALDI-TOF) Complemented with Selected 16S rRNA and gyrB Genes Sequencing to Practically Identify Clinical Important Viridans Group Streptococci (VGS).
There are challenges in viridans group streptococci (VGS) identification especially for the mitis group. Few studies have investigated the performance of MALDI-TOF MS system in VGS identification. Using 16S rRNA gene and gyrB gene sequencing as a gold standard, the performance of two MALDI-TOF MS instruments in the identification of 181 VGS clinical isolates was studied. The Bruker Biotyper and Vitek MS IVD systems correctly identified 88.4% and 98.9% of the 181 isolates, respectively. The Vitek MS RUO system was the least reliable, only correctly identifying 38.7% of the isolates to species level with several misidentifications and invalid results. The Bruker Biotyper system was very unreliable in the identification of species within the mitis group. Among 22 non-pneumococci isolates (S. mitis/S. oralis/S. pseudopneumoniae), Biotyper misidentified 21 of them as S. pneumoniae leading to a low sensitivity and low positive predictive value in these species. In contrast, the Vitek MS IVD demonstrated a better resolution for pneumococci and non-pneumococci despite the inability to distinguish between S. mitis/S. oralis. For more accurate species-level identification, further improvements in the VGS spectra databases are needed. Based on MALDI-TOF analysis and selected 16S rRNA gene plus gyrB genes sequencing, we designed a practical VGS identification algorithm.
Department of Clinical Laboratory, Peking Union Medical College Hospital, Chinese Academy of Medical SciencesBeijing, China; Graduate School, Peking Union Medical College, Chinese Academy of Medical SciencesBeijing, China.
Menglan
M
Zhou
Department of Clinical Laboratory, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences Beijing, China.
Qiwen
Q
Yang
School of Biomedical Sciences, Charles Sturt University Orange, NSW, Australia.
Timothy
T
Kudinha
Department of Clinical Laboratory, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences Beijing, China.
Li
L
Zhang
Department of Clinical Laboratory, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences Beijing, China.
Meng
M
Xiao
Centre for Infectious Diseases and Microbiology Laboratory Services, Westmead Hospital Westmead, NSW, Australia.
Fanrong
F
Kong
Department of Clinical Laboratory, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences Beijing, China.
Yupei
Y
Zhao
Department of General Surgery, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences Beijing, China.
Ying-Chun
YC
Xu
16S rRNA gene; Streptococcus; gyrB gene; matrix-assisted laser desorption ionization-time of flight (MALDI-TOF); viridans group streptococci (VGS)