Capsular polysaccharide type 5 of Staphylococcus aureus; Capsular polysaccharide type 8 of Staphylococcus aureus (CP5 (for type 5); CP8 (for type 8))

Capsular polysaccharides type 5 and 8 are extracellular, high-molecular-weight carbohydrates produced by most clinical isolates of *Staphylococcus aureus*. The bacterial capsule is a key *virulence factor* that protects S. aureus from host immune responses by impeding phagocytosis and masking cell wall-associated adhesins. CP5 and CP8 are chemically similar, each comprising a unique trisaccharide repeating unit with differences in glycosidic linkages and acetylation that confer serological distinction[4][5][6][8]. These capsular antigens facilitate bacteremia, persistence in host tissues, and are associated with increased ability to form abscesses. Because they are immunogenic and predominantly found in pathogenic isolates, CP5 and CP8 are leading candidates for multivalent S. aureus vaccines[2][6][7].

Other names

S. aureus capsule type 5S. aureus capsule type 8staphylococcal capsule type 5staphylococcal capsule type 8

For vaccines: induction of anti-capsule antibodies that promote opsonophagocytic killing. For antibiotics: capsule presence can reduce efficacy by impeding access to cell wall.