Ongoing Staphylococcus aureus (S. aureus) infections of the spine associated with orthopedic hardware implants elicit prominent immune responses against a repertoire of proteins characteristic of the invading pathogen. Antibodies specific for these antigens can be measured in the serum or in a novel sample created by culturing circulating Antibody Secreting Cells (ASC) in vitro where they create an analytic fluid called here "medium enriched for newly synthesized antibodies" (MENSA). The hypothesis of this study addresses three essential attributes of this analytic approach that can yield both a valuable tool for research on spinal infections and in the future, this can be developed a clinical tool for diagnosis and monitoring of therapeutic success in patients. By measuring the emergence of these signature antibodies in the serum and/or MENSA, the goals of this study are: 1) To differentiate between patients with an ongoing S. aureus infections, not just "general infection, in the spine using only blood samples; 2) To track the success (or failure) of therapeutic interventions; and 3) to distinguish spinal infections from S. aureus infections in other sites by the repertoire of antibodies that are elicited.
