Antibody response to Staphylococcus aureus collagen binding protein in patients with S. aureus septicaemia and collagen binding properties of corresponding strains.

An ELISA was developed for the detection of IgG antibodies to Staphylococcus aureus collagen binding protein (CnBP) in 95 patients with S. aureus endocarditis, complicated septicaemia with bone and joint involvement or uncomplicated septicaemia and in 95 control patients. Sixty percent of S. aureus-infected patients showed a positive peak anti-CnBP antibody level or a significant rise in titre, or both, during infection, but patients with S. aureus endocarditis or complicated septicaemia could not be differentiated from those with uncomplicated S. aureus septicaemia. The collagen binding capacity of S. aureus strains from 82 of the 95 patients was investigated in a particle agglutination assay and a 125I-labelled assay. All strains bound collagen in the particle agglutination assay as did 68% in the 125I-labelled assay, but there was no correlation between collagen binding of the patient strain and endocarditis, joint or skeletal involvement. An anti-CnBP antibody response was seen in 16 patients infected with a S. aureus strain negative for collagen binding in vitro, indicating in-vivo expression of CnBP.