Appropriate antimicrobial therapy reduced mortality rates in A. baumannii

Issue: September 2012

Mortality rates associated with Acinetobacter baumannii bacteremia in severely ill patients was significantly improved with appropriate antimicrobial therapy.

Perspective from Petros Rafailidis, MD

“The pathogenecity of Acinetobacter baumannii and the effect of appropriate antimicrobial therapy on this pathogen has been a controversial issue.” TeLi Chen, MD,of the division of infectious diseases at Taipei Veterans General Hospital in Taiwan, told Infectious Disease News. “We confirmed that A. baumannii is associated with a high mortality rate in severely ill patients and that appropriate antimicrobial therapy implemented within 48 hours of bacteremia onset is crucial for the patients’ outcome.”

TeLi Chen

Chen and colleagues conducted a retrospective study to determine whether appropriate antimicrobial therapy had an effect on 14-day mortality. The study included 252 patients with monomicrobial A. baumannii bactermia.

Overall, the 14-day mortality rate was 29.8%. After multivariate analysis, appropriate antimicrobial therapy was shown to be associated with reduced mortality (OR=0.22; 95% CI, 0.10-0.50). In addition, malignancy (OR=3.48; 95% CI, 1.58-7.68) and APACHE II score (OR=1.18; 95% CI, 1.13-1.24) were also predictors of mortality.

Interactions between APACHE II score and appropriate antimicrobial therapy were also observed. Appropriate antimicrobial therapy did not affect patients with APACHE II scores of =15 or scores of >15 and =25. Patients with APACHE II scores of >25 and =35 and >35 had significantly reduced mortality when they received antimicrobial therapy.

“For patients with sepsis and at risk for A. baumannii bacteremia, implementation of an antimicrobial agent that is active against A. baumannii is warranted,” Chen said. “A study evaluating the impact of rapid identification of patients with A. baumanii bacteremia with a rapid identification method followed by implementation of appropriate therapy is ongoing.”

References:

Lee Y. Clin Infect Dis. 2012;55:209-215.

Disclosures:

Dr. Chen is a medical advisor for TTY biopharm..

Perspective

Petros Rafailidis, MD

Despite its retrospective design, this study is very important because it was performed in a large tertiary care teaching hospital over an 8-year period. Furthermore, a well-defined 14-day mortality outcome was used by the authors. In addition, A. baumannii was identified to the genomic species level by using molecular techniques (Polymerase Chain Reaction). The key finding of the study is that appropriate antibiotic therapy was independently associated with markedly reduced 14-day mortality [OR: 0.22, 95% CI: 0.01-0.50, p<0.001]. Interestingly, this reduced mortality was observed in the sickest patients i.e. those with higher APACHE II scores. This finding refutes the belief held by some scientists that A. baumannii is a low virulence bacterium and that patients die not because of it, but rather from comorbidities. Infectious diseases specialists should be aware of this study as it stresses the importance of using appropriate antibiotics in the setting of A. baumannii bacteremia.

Petros Rafailidis, MD

Alfa Institute of Biomedical Sciences, Athens, Greece

Disclosures: