Influence of carbapenem resistance on mortality and the dynamics of mortality in Pseudomonas aeruginosa bloodstream infection.

Objective: We aimed to study the influence of carbapenem resistance on attributable mortality in a cohort of patients with Pseudomonas aeruginosa bacteremia.

Methods: Data on 121 episodes of P. aeruginosa bacteremia occurring between January and December 2005 were retrospectively analyzed.

Results: Thirty-three episodes were caused by carbapenem-resistant P. aeruginosa (CRPA) strains and 88 by carbapenem-susceptible P. aeruginosa (CSPA) strains. There was no significant difference in mortality between the groups (33% in CRPA vs. 30% in CSPA; p = 0.69). However, a Kaplan-Meier survival analysis showed that in the first 48h after the onset of bacteremia, there was a lower cumulative mortality proportion in the CRPA group than in the CSPA group (13% vs. 50%; p = 0.026). The independent risk factors associated with death in P. aeruginosa bacteremia were clinical presentation with severe sepsis (odds ratio (OR) 38, 95% confidence interval (CI) 10.2-142.2) and bacteremia of high-risk origin (OR 6.6, 95% CI 1.6-26.9).

Conclusions: According to our data, carbapenem resistance was not associated with higher mortality in patients with P. aeruginosa bacteremia. The slower initial mortality in the CRPA group might have implications in the design of the optimal antibiotic policy strategy.