Staphylococcus aureus bacteremia in the surgical patient: A prospective analysis of 73 postoperative patients who developed Staphylococcus aureus bacteremia at a tertiary care facility

Background: Staphylococcus aureus is a frequent cause of infection and bact eremia in the postoperative patient. Unfortunately there have been no prosp ective studies evaluating these patients, so the incidence of complications , subsequent treatment algorithms, and prognosis remain undefined. The obje ctives of this prospective study of postoperative Staphylococcus aureus bac teremia (SAB) were to define the primary sources of bacteremia and to ident ify the common complications of SAB in the postoperative setting. Methods: A registry was developed into which 309 consecutive adult patients with SAB were prospectively enrolled between September 1994 and December 1 996. Seventy-three of these patients (23.6%) developed SAB in the postopera tive setting. Results: Analysis of the clinical features of these 73 postoperative patien ts revealed three important results. First, infective endocarditis is surpr isingly common in postoperative patients with SAB and the classical stigmat a of endocarditis are often absent. Transesophageal echocardiography was pe rformed in 31 of 73 patients; 10 of these patients (32.3%) met Duke Criteri a for definite endocarditis, but only 3 of these patients had vegetations d etected by transthoracic echocardiography, and only 2 patients had peripher al stigmata of infective endocarditis. Second, the development of SAB after cardiothoracic surgery was strongly as sociated with underlying S. aureus mediastinitis. Twenty-one of the 23 pati ents who developed SAB after median sternotomy had mediastinitis (positive predictive value 91.3%). In many cases, the diagnosis of mediastinitis was not apparent when SAB was detected. Third, complications, relapses, and mortality were high in postoperative pa tients with SAB. Fourteen of 73 patients (19.2%) developed multiple noncard iac metastatic complications, including metastatic abscesses (5), septic em boli (3), pneumonia or empyema (2), septic arthritis (I), epidural abscess (1), and other metastatic foci (7). Twelve of 73 patients (16.4%) had recur rent staphylococcal infection after treatment of their first episode of SAB , including 8 patients (11.0%) with recurrent bacteremia. Of patients who s urvived, those with recurrent staphylococcal infection were more likely to have an infected surgical wound than were patients who were cured of infect ion (p = 0.05). Finally, mortality attributable to SAB (11.0%), and all-cau se mortality (21.9%), was high. Conclusions: SAB in the postoperative setting is often a severe disease wit h high morbidity and mortality A thorough diagnostic evaluation is indicate d in surgical patients with S. aureus bacteremia to ensure the early detect ion of metastatic infections such as infective endocarditis and to define f oci such as mediastinitis requiring surgical intervention. (J Am Coll Surg 2000;190:50-57. (C) 2000 by the American College of Surgeons).