Risk Factors of 30-Day Mortality in Acinetobacter baumannii Complex Bacteremia

Bacterium Acinetobacter baumannii, bacteria resistant to antibiotics. 3d illustration
Researchers assessed potential risk factors associated with 30-day mortality among patients with Acinetobacter baumannii complex bacteremia.

Immunosuppression and increased disease severity were found to be independent risk factors of 30-day mortality in patients with Acinetobacter baumannii complex bacteremia, according to results of a single-center retrospective study published in the American Journal of Infection Control.

Researchers obtained data on adult patients (N=188) with A baumannii complex bacteremia who were admitted to an intensive care unit at a tertiary care hospital between January 2009 and December 2020. The researchers evaluated differences in clinical profiles and prognoses between patients with pneumonia- (group 1) and nonpneumonia-related (group 2) A baumannii complex bacteremia. The primary outcome was 30-day mortality. Disease severity was determined via Charlson comorbidity index, Pitt bacteremia, acute physiology and chronic health evaluation II (APACHE II), and sequential organ failure assessment (SOFA) scores.

Among patients included in groups 1 (n=44) and 2 (n=144), the mean age was 65.3±15.1 and 59.9±17.5 years (P =.051), 25.0% and 28.5% were men, 56.8% and 31.9% had hypertension (P =.003), 2.3% and 13.9% received tigecycline within the past month (P =.030), and carbapenem resistance was noted in 100.0% and 88.2% (P =.014), respectively.

The researchers found that the median duration of hospitalization was significantly decreased among patients in group 1 vs those in group 2 (16.5 vs 27.0 days; P =.013). Further analysis showed that 30-day mortality rates were significantly increased among patients in group 1 vs those in group 2 (75.0% vs 57.6%; P =.038). Although the risk of mortality was 1.92 times higher among patients in group 1 vs those in group 2, the difference was not statistically significant (P =.171).

A multivariate logistic regression analysis showed that immunosuppression (odds ratio [OR], 3.88; 95% CI, 1.67-9.06; P =.002) at the time of diagnosis, as well as higher APACHE II (OR, 1.08; 95% CI, 1.03-1.15; P =.005) and SOFA scores (OR, 1.24; 95% CI, 1.11-1.40; P <.001), were significant independent risk factors of 30-day mortality.

This study was limited by its small sample size, its retrospective design, and its single-center setting. The researchers also noted the inability to determine whether the virulence of A baumannii complex strains changed significantly over time.

According to the researchers, “… clinicians should pay more attention to patients’ immune status and the severity of the disease to improve the prognosis” of A baumannii complex bacteremia.


Xu J, Xu Y, Zheng X. Comparison of pneumonia- and non-pneumonia-related Acinetobacter baumannii complex bacteremia: a single-center retrospective study. Am J Infect Control. Published online August 7, 2022. doi:10.1016/j.ajic.2022.08.004