Comparison between bacteremia caused by Acinetobacter pittii and Acinetobacter nosocomialis

Patients with Acinetobacter pittii and Acinetobacter nosocomialis bacteremia have lower mortality rates than those with Acinetobacter baumannii bacteremia. However, it is unknown whether these organisms differ in outcomes of bacteremic patients. We conducted this study to answer this question.

In this retrospective study conducted at a teaching hospital in Taiwan, we enrolled all 86 patients who had developed A. pittii bacteremia and those with A. nosocomialis bacteremia from 2000 to 2008 while matching for age, sex, Acute Physiology and Chronic Health Evaluation II score, and appropriate antimicrobial therapy. After adjustment, we accessed the clinical characteristics and 14- and 28-day mortalities.

We found that the patients with A. pittii bacteremia had multiple comorbidities less often and received invasive procedures less frequently. The 14-day mortality rate of patients with A. pittii or A. nosocomialis bacteremia was 14% and 7%, respectively, whereas their 28-day mortality rate was 17% and 9%, respectively. Using the mortality rate in patients with A. nosocomialis bacteremia as a reference, the odds ratios for the 14- and 28-day crude morality in those with A. pittii were 2.16 [95% confidence interval (CI), 0.77-6.05] and 2.06 (95% CI, 0.82-5.15), respectively, whereas the adjusted odds ratios for 14- and 28-day mortality were 1.89 (95% CI, 0.56-6.14) and 1.67 (95% CI, 0.59-4.78) respectively.

Our 8-year study showed that the mortality rate of A. pittii bacteremia was higher but the difference was not statistically significant.