Explore the recorded discovery and history of Streptococcus agalactiae, with source links and stated limits.
CDC states that group B Streptococcus bacteria commonly live in people’s gastrointestinal and genital tracts, and that pregnant women can pass the bacteria to their babies during delivery, with most babies who get GBS disease in the first week of life exposed this way. PHAC describes a Gram-positive facultative anaerobe measuring 0.5-1.0 by 1.0-2.0 micrometres, appearing in pairs or chains of up to 50 cells or more, beta-haemolytic on blood agar, with nine serotypes. PHAC reports that 10 to 30% of women are colonized and asymptomatic, and that about 2% of all infants are infected although 75% of infants exposed are colonized without any clinical signs. Carriage is therefore the usual outcome and disease the exception.
LPSN records Streptococcus agalactiae Lehmann and Neumann 1896, effectively published in their Atlas und Grundriss der Bakteriologie and retained on the 1980 Approved Lists of Bacterial Names. The epithet comes from the Greek for want of milk, because the organism was first associated with bovine mastitis — the name records a veterinary context, not human disease. Type strain ATCC 13813 / DSM 2134 / NCTC 8181.
These references do not identify a first person ever infected. The species was named in a veterinary context in 1896, long before its role in newborn infection was recognised, so the naming date cannot stand in for a first human case.
Source check: 2026-09-20. Educational content; independent scientific review remains pending.