Teichoic acid antibody and circulating immune complexes in the management of Staphylococcus aureus bacteremia

Optimal antibiotic therapy for patients with Staphylococcus aureus bacteremia remains controversial. The results of two serologic tests, teichoic acid antibody and circulating immune complexes, have shown promise in detecting patients who have serious bacteremia (sustained bacteremia with endocarditis or metastatic abscess) and require longer, more intensive treatment. These tests were performed on serial samples from 38 patients with staphylococcal bacteremia prospectively categorized by severity of infection and by risk factors associated with serious disease (sustained bacteremia, valvular heart disease, absence of focus of infection, metastatic abscess). A surprisingly large group of these patients (20, or 53 percent) could not be prospectively defined as having "serious" or "benign" bacteremia. Neither test differentiated patients with serious bacteremia from those with benign bacteremia. Although it is possible that additional significant associations with risk factors might have been obtained with the teichoic acid antibody test had more patients been included, positive tests were found more frequently only in patients in whom metastatic abscesses developed. The teichoic acid antibody test was found to be a sensitive, but not specific, indicator of serious staphylococcal disease and was of value in excluding serious infection only when a negative results was supported by clinical evidence for benign disease. Other than this use, neither assay was helpful in determining optimal therapy of staphylococcal bacteremia.