Use of MALDI-TOF mass spectrometry for rapid identification of group B Streptococcus on chromID Strepto B agar

Int J Infect Dis. 2014 Oct;27:44-8. doi: 10.1016/j.ijid.2014.06.023. Epub 2014 Aug 23.


Background: Group B Streptococcus (GBS) is a known leading causative pathogen of neonatal infection. Efficient screening and identification of women colonized with GBS is important for the prevention of invasive neonatal infections.

Methods: A total of 628 vaginal/rectal specimens were collected from pregnant women in Beijing, China. The chromogenic medium chromID Strepto B agar (STRB) was evaluated for its reliability in screening GBS from the vaginal/rectal swabs; results were compared to those of blood agar plates (BAP). Furthermore, matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) was used to confirm the colonies suspected of being GBS on STRB.

Results: STRB showed excellent performance for GBS detection and outperformed BAP due to its higher sensitivity. Furthermore, MALDI-TOF MS could reliably differentiate the putative GBS isolates on STRB.

Conclusions: This study demonstrated that STRB combined with MALDI-TOF MS is a fast, sensitive, and accurate method for the identification of GBS-colonized pregnant women.

Keywords: Group B Streptococcus; Matrix-assisted laser desorption ionization–time of flight mass spectrometry; chromID Strepto B agar.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Agar
  • Bacteriological Techniques
  • Female
  • Humans
  • Pregnancy
  • Pregnancy Complications, Infectious / diagnosis
  • Pregnancy Complications, Infectious / microbiology
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / methods*
  • Streptococcal Infections / diagnosis
  • Streptococcal Infections / microbiology
  • Streptococcus agalactiae / chemistry
  • Streptococcus agalactiae / classification*
  • Streptococcus agalactiae / isolation & purification
  • Vagina / microbiology
  • Young Adult


  • Agar