A new serological assay for Staphylococcus aureus infections: detection of IgG antibodies to S. aureus lipase with an enzyme-linked immunosorbent assay.

Purified Staphylococcus aureus lipase was used as antigen in an enzyme-linked immunosorbent assay (ELISA) that detected IgG antibodies in 169 patients with infections due to S. aureus, in 122 patients with infections not due to S. aureus, and in 167 healthy controls. Eighty-eight percent (21 of 24) of the patients with endocarditis due to S. aureus showed a positive level of antibody to lipase or a significant change in antibody titer during the first month, as did 89% (17 of 19) and 28% (5 of 18) of the patients with complicated and uncomplicated septicemia due to S. aureus, respectively. The specificity for S. aureus infections was high; only one patient in the non-S. aureus endocarditis and septicemia groups showed a significant rise in antibody titer, and this rise did not reach a positive antibody level. Patients with recurrent furunculosis or chronic osteomyelitis due to S. aureus responded in only 15% and 23% of cases, respectively. We suggest that the antibody-to-lipase ELISA could be used as a valuable complement to other serological assays in diagnosing serious S. aureus infections because of its high sensitivity and specificity.