ADHERENCE AND SURFACE-PROPERTIES OF BUOYANT DENSITY SUBPOPULATIONS OFGROUP-B STREPTOCOCCI, TYPE-III

From clinical isolates of group B streptococci, buoyant density subpop ulations with variable amounts of type-specific polysaccharide can be derived. The ability of these subpopulations to adhere to vaginal epit helial cells and to glass was assessed by using [H-3]-labeled bacteria . Subpopulations with no or minute amounts of capsule showed good adhe rence capacity and a hydrophobic cell surface. In contrast, a large ca psule made the bacteria less adherent and rendered their surface hydro philic. A negative cell surface charge, judged by determination of the z-potential, was directly related to the amount of capsule. Proteinas e K treatment of less encapsulated variants significantly decreased th e cell hydrophobicity. The ability of a GBS strain to express differen t surface characteristics may be a mechanism for adaptation to environ mental changes, and may thereby contribute to the pathogenicity of GBS .