A common gut and genital-tract resident in adults that occasionally causes serious infection in newborns. Explore its illustrative 3D model, human context, and sources.
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.
PHAC records 10 to 30% of women colonized and asymptomatic and 75% of exposed infants colonized without clinical signs, alongside a 20% mortality rate for neonatal infections and 15% mortality in adults aged 65 or older. Carrying this organism is normal; invasive disease is uncommon and concentrated in newborns, pregnancy-related infection and older or immunocompromised adults. A colonisation result is not a diagnosis.
Streptococcus agalactiae · Seven slightly ovoid cocci suggest a representative chain; the translucent coat is an encapsulated phenotype of unspecified serotype. This is a species-informed teaching diagram; colours, proportions, envelope spacing and internal detail are illustrative. The model uses muted illustrative colours; stains, colony pigments and microscopy colourization are not natural cell colours. Anatomy is enlarged for phone viewing. Morphology reference: Streptococcus agalactiae · pathogen safety data sheet.
Source check: 2026-09-20. Educational content; independent scientific review remains pending.