Clinical characteristics and outcomes of bacteremia due to different genomic species of Acinetobacter baumannii complex in patients with solid tumors

Purpose Acinetobacter baumannii, Acinetobacter genomic species 3 (AGS 3), and Acinetobacter genomic species sensu Tjernberg and Ursing (AGS 13TU) are phenotypically indistinguishable and are often reported together as the A. baumannii complex (ABC). Few studies have investigated the difference in outcome caused by these different species, and all involved heterogeneous groups of patients. This study aimed to delineate whether there are differences in the clinical characteristics and outcome among patients with solid tumors and bacteremia caused by A. baumannii or two other non-baumannii ABC species (AGS 3 plus AGS 13TU). Methods Patients with solid tumors and ABC bacteremia over a period of 5 years in a medical center were identified. The patient data were retrospectively reviewed and analyzed. Results We identified 103 patients with ABC bacteremia during the study period. Bacteremia was due to A. baumannii in 30 patients, AGS 3 in 24 patients, and AGS 13TU in 49 patients. Among the 103 patients with ABC bacteremia, recent stay in the intensive care unit (ICU) (p = 0.008) was independently associated with the acquisition of A. baumannii bacteremia. Multivariate analysis revealed that bacteremia caused by A. baumannii (hazard ratio [HR] 2.990, 95% confidence interval [CI], 1.021-8.752, p = 0.046) and Acute Physiology and Chronic Health Evaluation (APACHE) II score >= 21 (HR 4.623, 95% CI 1.348-15.859, p = 0.015) were independent factors associated with 14-day mortality. Conclusions Infection with A. baumannii and a high APACHE II score (>= 2) might be associated with poor outcome in patients with solid tumors and ABC bacteremia.