Yes, Streptococcus agalactiae is Group B Streptococcus
Streptococcus agalactiae and Group B Streptococcus (GBS) are the same organism—these terms are used interchangeably to refer to the identical gram-positive bacterium. 1, 2
Microbiological Identity
S. agalactiae is definitionally Group B Streptococcus, classified as a gram-positive coccus that causes invasive disease primarily in newborns, pregnant women, and adults with underlying medical conditions 2
The organism is also described as a gram-positive bacterium that causes invasive disease primarily in infants, pregnant or postpartum women, and older adults, with the highest incidence among young infants 1
Clinical Context
The terminology is used consistently across all major guidelines and clinical literature:
CDC prevention guidelines explicitly state "Group B Streptococcus, or Streptococcus agalactiae" when introducing the organism, confirming these are synonymous terms 1, 2, 1
The bacterium colonizes the gastrointestinal and genitourinary tracts, with approximately 10-30% of pregnant women colonized in the vaginal or rectal area 1, 2
Recent research continues to use both names interchangeably, referring to "Streptococcus agalactiae (Group B Streptococcus, GBS)" when describing clinical isolates and infections 3, 4, 5
Important Distinction from Group A Streptococcus
Do not confuse with Group A Streptococcus (Streptococcus pyogenes), which is a completely different organism that causes pharyngitis and other distinct infections 6
Group A and Group B streptococci are classified by different Lancefield groupings based on their cell wall carbohydrate antigens and cause entirely different disease patterns 2