Laboratory Testing for Group B Streptococcus

Key Points

  • Laboratory methods for group B Streptococcus (Streptococcus agalactiae, GBS) screening and testing have not changed substantially over the past decade.
  • Culture remains the gold standard method.
Illustration of group B Streptococcus

Laboratory guidelines

In 2021, the American Society for Microbiology (ASM) released new guidelines for detecting and identifying GBS to prevent disease in newborns. ASM's guidelines replace the 2010 guidelines published by CDC.

View ASM's Guidelines for the Detection and Identification of Group B Streptococcus.


CDC Streptococcus Laboratory

Domestically, the CDC Streptococcus Laboratory supports the national population-based Active Bacterial Core surveillance through

  • Serotyping of GBS isolates
  • Antimicrobial susceptibility testing
  • Strain characterization by whole-genome sequencing

The lab supports training and development of improved strain surveillance methods.

Learn more about the CDC Streptococcus Laboratory and its epidemiologic and reference services.