Risk Factors for Mortality in Patients with Pseudomonas aeruginosa Bacteremia: Clinical Impact of Antimicrobial Resistance on Outcome

Despite the high prevalence of antimicrobial resistance among Pseudomonas aeruginosa bacteremia, the clinical consequence of resistance remains unclear. The purpose of this study was to identify predictors of mortality and evaluate the clinical impact of antimicrobial resistance on outcome in P. aeruginosa bacteremia. A retrospective cohort study including patients with P. aeruginosa bacteremia was performed. The risk factors for antimicrobial resistances were evaluated, and the impact of the respective resistances on mortality was assessed. Of 202 P. aeruginosa bacteremia cases, the resistance rates to ceftazidime, piperacillin, imipenem, fluoroquinolone, and aminoglycoside were 36.6%, 22.3%, 22.8%, 23.8%, and 17.8%, respectively. A prior use of fluoroquinolones and an indwelling urinary catheter were common risk factors for all types of antimicrobial resistance. The overall 30-day mortality rate was 25.2% (51/202), and the risk factors for mortality were corticosteroid use, nosocomial acquisition, polymicrobial infection, an increasing Charlson's weighted co-morbidity index, and intensive care unit care (p < 0.05). As compared with the susceptible group, ceftazidime-, piperacillin-, or imipenem-resistant groups had a higher mortality (p < 0.05). A multivariate analysis showed that resistance to ceftazidime or imipenem remained a significant factor associated with mortality (odds ratio, 2.96; 95% confidential interval, 1.20-7.31; and odds ratio, 2.74; 95% confidential interval, 1.02-7.31, respectively). Antimicrobial resistance, especially to ceftazidime or imipenem, adversely affected outcome in patients with P. aeruginosa bacteremia.