<i>Pseudomonas aeruginosa</i> Bacteremia among Immunocompetent and Immunocompromised Patients: Relation to Initial Antibiotic Therapy and Survival

<i>Pseudomonas aeruginosa</i> bacteremia occurs mainly in immunocompromised patients. However, <i>P. aeruginosa</i> bacteremia in immunocompetent patients has also been reported. The aim of this study was to evaluate the clinical characteristics of <i>P. aeruginosa</i> bacteremia in relation to the immune status of the patients. The medical records of 126 adult patients with <i>P. aeruginosa</i> bacteremia in Nagasaki University Hospital were retrospectively reviewed between January 2003 and December 2012. Of 126 patients with <i>P. aeruginosa</i> bacteremia, 60 patients (47.6%) were classified as immunocompetent. Mortality in immunocompetent patients tended to be lower than in immunocompromised patients (7-day mortality, 8% vs. 30%, <i>P</i> < 0.01; 30-day mortality, 23% vs. 39%, <i>P</i> = 0.053). Multivariate analysis showed that a higher sequential organ failure assessment score (hazard ratio [HR]: 1.27, <i>P</i> < 0.01) and underlying malignancies (HR: 3.33, <i>P</i> < 0.01) were independently associated with 30-day mortality. Initial antibiotic therapy (HR: 0.21, <i>P</i> < 0.01) and patients' immune status (HR: 0.29, <i>P</i> = 0.02) also had a significant impact on survival. However, there was a significant interaction between these 2 variables (<i>P</i> = 0.03 for interaction). A subgroup analysis showed that in immunocompromised, but not immunocompetent patients, initial appropriate antibiotic therapy was associated with lower mortality (30-day mortality 20.5% vs. 66.7%, <i>P</i> < 0.01 by log-rank test).