Serum and tissue protein binding and cell surface properties of Staphylococcus lugdunensis

Summary. Eleven strains of Staphylococcus lugdunensis from different clinical sources were investigated for their ability to bind 12'I-labelled collagen (Cn) type I and IV, fibronectin (Fn), vitronectin (Vn), laminin (Lm), fibrinogen (Fg), thrombospondin, plasminogen (glu- and lys-form) and human IgG. All the strains bound these proteins, although a higher degree of binding was obtained for Cn types I and IV and IgG with mean values of 36 YO, 32 YO and 26 YO binding. respectively. In tests with proteins immobilised on latex beads in a particle agglutination assay, eight of the 11 strains bound Cn type I and seven bound Fg, whereas no strain bound immobilised IgG. Binding to immobilised Cn-I, Fg, Lm and Vn was abolished when the bacterial cells were treated with proteases or heat, indicating cell-surface receptors with protein characteristics. Cell-surface extracts of S. lugdunensis 2342 were able to totally inhibit binding of the homologous strain and S. aureus Cowan 1 to latex-immobilised proteins Cn-I, Lm, Vn, Fn and Fg. The binding of '"I-labelled Cn IV by S. lugdunensis 2342, was heat sensitive, whereas the binding to S. auieus Cowan 1 was heat resistant. The strains gave negative results in tests for the presence of protein A with a S. aureus protein A gene probe and with sensitised red blood cells. No production of heat-stable nuclease (TNase) could b