Identification of Streptococcus pseudopneumoniae and other mitis group streptococci using matrix assisted laser desorption/ionization - time of flight mass spectrometry

Diagn Microbiol Infect Dis. 2021 Nov;101(3):115487. doi: 10.1016/j.diagmicrobio.2021.115487. Epub 2021 Jul 10.

Abstract

This study evaluated the ability of the MALDI-ToF MS from Bruker Daltonics to identify clinical Mitis-Group-Streptococcus isolates with a focus on Streptococcus pseudopneumoniae. The results were analyzed using the standard log(score) and the previously published list(score). Importantly, using the log(score) no misidentifications occurred and 27 of 29 (93%) S. pneumoniae and 27 of 30 (90%) S. oralis strains were identified, but only 1 of 31 (3%) S. pseudopneumoniae and 1 of 13 (8%) S. mitis strains were identified. However, our results show that 30 of 31 S. pseudopneumoniae strains had a S. pseudopneumoniae Main Spectral Profiles within the 3 best matches. Using the list(score) all S. oralis and S. pneumoniae strains were identified correctly, but list(score) misidentified 10 S. pseudopneumoniae and 5 S. mitis. We propose to use the log(score) for identification of S. pneumoniae, S. pseudopneumoniae, S. mitis and S. oralis, but for some strains additional testing may be needed.

Keywords: MALDI-ToF MS; Mitis Group; Streptococcus; Streptococcus pneumoniae; Streptococcus pseudopneumoniae; Whole genome sequencing.

MeSH terms

  • Genome, Bacterial
  • Humans
  • Sequence Analysis, DNA
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / methods*
  • Streptococcus / chemistry*
  • Streptococcus / classification*
  • Streptococcus / genetics
  • Streptococcus / isolation & purification
  • Viridans Streptococci / chemistry*
  • Viridans Streptococci / classification
  • Viridans Streptococci / genetics
  • Viridans Streptococci / isolation & purification
  • Whole Genome Sequencing

Supplementary concepts

  • Streptococcus pseudopneumoniae