GBS meaning in Medical ?

Streptococcus agalactiae (also known as group B streptococcus or GBS) is a gram-positive coccus (round bacterium) with a tendency to form chains (as reflected by the genus name Streptococcus). It is a beta-hemolytic, catalase-negative, and facultative anaerobe.

S. agalactiae is the species designation for the only species of streptococci belonging to the group B of the Rebecca Lancefield classification of streptococci. GBS is surrounded by a bacterial capsule composed of polysaccharides (exopolysacharide). The species is subclassified into ten serotypes (Ia, Ib, II–IX) depending on the immunologic reactivity of their polysaccharide capsule. This is why the plural term group B streptococci (referring to the serotypes) and the singular term group B streptococcus (referring to the single species) are both commonly encountered.

In general, GBS is a harmless commensal bacterium being part of the human microbiota colonizing the gastrointestinal and genitourinary tract of up to 30% of healthy human adults (asymptomatic carriers). Nevertheless, GBS can cause severe invasive infections especially in newborns, the elderly, and people with compromised immune systems.

S. agalactiae is also a common veterinary pathogen, because it can cause bovine mastitis (inflammation of the udder) in dairy cows. The species name agalactiae meaning "of no milk", alludes to this.