Risk Factors and Clinical Outcomes of Mixed Acinetobacter Baumannii Bloodstream Infection

Abstract Background: Although the clinical features of Acinetobacter baumannii bloodstream infection are well described, the specific clinical characteristics of mixed Acinetobacter baumannii bloodstream infection are rarely reported. The objective of this study was to examine the risk factors and clinical outcomes of mixed Acinetobacter baumannii bloodstream infection. Methods: A retrospectively observational study was performed from January 2013 to December 2018 in a tertiary hospital. All patients with Acinetobacter baumannii bloodstream infection were enrolled,the data were collected from electronic medical records. Results: A total of 594 episodes were enrolled, 21% (126/594) of which were mixed Acinetobacter baumannii bloodstream infection.The most common co-pathogens were Klebsiella pneumoniae (20.81%), followed by Pseudomonas aeruginosa (16.78%) and Enterococcus faecium (12.08%). Compared with monomicrobial Acinetobacter baumannii bloodstream infection, the main source of mixed Acinetobacter baumannii bloodstream infection was from skin and soft tissue(28.6% vs.10.5%, P<0.001). A multivariate analysis revealed burn injury was independently associated with mixed Acinetobacter baumannii bloodstream infection(adjusted odds ratio,3.569; 95% confidence interval, 1.954-6.516). Patients with mixed Acinetobacter baumannii bloodstream infection were more likely to have longer hospitalization length of stay [40(21,68) vs. 27(16,45), P<0.001]and hospitalization days after BSI [22(8,50) vs. 13(4,28), P<0.001]. However, no significant difference in mortality was observed between the two groups. Conclusions: Mixed Acinetobacter baumannii bloodstream infection is not a rare event, which accounts for one fifth of all Acinetobacter baumannii bloodstream infection. The main source is from skin and soft tissue, and burn injury is an independent risk factor. Although the mortality is not different, patients with mixed Acinetobacter baumannii bloodstream infection might have poor outcomes, which merits more attention by physicians in the future.