Occasional Review: Group-B Streptococcus--Profile of an Organism

Abstract

Introduction and historical review P. W. Ross Nocard and Mollereau (1 887) were the first to describe the isolation of streptococci from bovine mastitis and these organisms were likely to have been the group-B streptococci (GBS). Many years elapsed, however, before these streptococci featured again in the literature. In 1933, Rebecca Lancefield divided streptococci into groups on the basis of carbohydrate antigens in the cell wall; her classification scheme was based on precipitation reactions of hot-hydrochloric-acid extracts of whole organisms (Lancefield extracts) with antisera raised in rabbits against whole-cell formalinised streptococci. These classical studies clarified the taxonomy of streptococci to a considerable degree because the cultural and biochemical patterns that had been used before 1933 had added little to streptococcal identification. The streptococci that Lancefield described as group B were isolated from bovine and dairy sources. In 1934 she divided GBS into types I, I1 and I11 and in 1938 subdivided type I into Ia and Ib. All the antigens were polysaccharides. Pattison, Matthews and Maxted (1955) added to the serological profile of GBS by describing two protein antigens, R and X. They also stated that GBS from human and bovine sources were not similar and this was corroborated by Butter and de Moor (1967). Wilkinson (1975) discovered a third protein antigen and called it Icp. It is generally referred to as the Ic protein and is usually found in strains with the Ia or Ib polysaccharide. Strains possessing the Ia and Ic antigens are said to belong to type Ic. The Icp antigen may be found in strains with the I1 or the I11 polysaccharide or without a detectable polysaccharide antigen. With serological tests that identify carbohydrate and protein antigens, many combinations of antigens are found-Ia, Ib, Ic, Icp, 11,

Emergence and Global Dissemination of Host-Specific Streptococcus agalactiae Clones

“…After 1960, GBS became the leading cause of invasive neonatal infections in developed countries (5, 6). The reason for this change in human disease incidence, which does not appear to be associated with increased attention or improved diagnostic techniques, remains unknown (4, 7). GBS rarely cause infections in healthy adults; however, occasionally it may cause morbidity in the elderly, in pregnant women, and in patients with underlying predisposing conditions (8).…”