Serological diagnosis of deep Staphylococcus aureus infections by enzyme-linked immunosorbent assay (ELISA) for staphylococcal hemolysins and teichoic acid.

An enzyme-linked immunosorbent assay (ELISA) was used with a purified alpha-toxin preparation to measure the serum IgG, IgM and IgA response in staphylococcal septicaemia and endocarditis. ELISA for IgG antibodies against alpha-toxin was found to be more sensitive than the neutralization test (ASTA). IgM and IgA antibody determination was found to be of limited diagnostic value. A correlation between IgG antibodies to alpha-toxin and purified beta-toxin was found in ELISA, although antibody determination to beta-toxin was a less sensitive diagnostic method. The highest diagnostic sensitivity in deep staphylococcal infections was obtained by parallel performance of ELISA to alpha-toxin and purified teichoic acid. By this approach, 32/35 (91%) patients with endocarditis, 12/14 (86%) with complicated septicaemia and 15/22 (68%) with uncomplicated septicaemia showed increased titres in samples drawn between days 7-30 of disease. Diagnostic sensitivity was further increased to 31/32 (97%) positive patients, when paired or multiple samples from patients with septicaemic staphylococcal disease were analysed.