Bloodstream infections in adult patients with cancer: clinical features and pathogenic significance of Staphylococcus aureus bacteremia

The aim of this study was to more precisely delineate the characteristics and outcomes of bloodstream infections in adult cancer patients. Using a database for nationwide surveillance of bacteremia, we analyzed data related to bacteremia in adult patients with cancer in order to evaluate clinical features and outcomes and to define predictive factors for mortality. Of 1,246 patients, 896 (71.9%) had solid tumors, 328 (26.3%) had hematologic malignancies, and 22 (1.8%) had both. The following conditions were more common in the neutropenic group than in the non-neutropenic group: nosocomial acquisition, hematologic malignancy, corticosteroid use, immunosuppressant use, primary bacteremia, and pneumonia (all P < 0.05). The infections were caused by Gram-negative bacilli in 55.6% and by Gram-positive cocci in 32.7%. Gram-negative pathogens were more frequently isolated from neutropenic patients than from non-neutropenic patients (61.9% vs. 53.5%, P = 0.010), with a significant predominance of Escherichia coli and Klebsiella pneumoniae. Among 1,001 patients whose outcomes could be evaluated, the overall 30-day mortality rate was 24.1%, and multivariate analysis showed that Staphylococcus aureus bacteremia was a significant factor associated with mortality (odds ratio (OR), 1.80; 95% confidence interval (CI), 1.03-3.15), along with nosocomial acquisition, pneumonia, severe sepsis or septic shock, and higher Pitt bacteremia score (all P values < 0.05). This study represents the comprehensive assessment of bloodstream infections in neutropenic versus non-neutropenic cancer patients. Given the pathogenic significance of S. aureus bacteremia in adult patients with cancer, additional strategies for the management of S. aureus bacteremia in cancer patients are needed to improve outcomes.