Pseudomonas aeruginosa infection in intensive care: Epidemiology, outcomes, and antimicrobial susceptibilities.

Background: Pseudomonas aeruginosa (PA) infection in the intensive care unit (ICU) contributes to substantial mortality. In this study, we describe the epidemiology, antimicrobial susceptibilities, and outcomes of ICU patients with pseudomonal infection.

Methods: ICU patients with PA were identified and classified as colonized or infected. Infected patients were reviewed for source, patient characteristics, antimicrobial susceptibilities, appropriateness of empiric antimicrobial therapy, and 30-day mortality. Independent predictors of mortality were identified using multivariable logistic regression.

Results: One hundred forty (71%) patients with PA were infected. Mean patient age was 55 (SD 18) years; 62% were male. Admission categories included medical (71%), surgical (20%), and trauma or neurological (9%). Mean Acute Physiology and Chronic Health Evaluation (APACHE) II score was 19 (SD 10). One hundred twenty-six (90%) patients were mechanically ventilated, 102 (73%) required vasopressors, and 27 (19%) received renal replacement; 32 (23%) died within 30 days. Infection was nosocomial in 101 (72%) cases. Sources were respiratory (66%), skin-soft tissue (11%), urinary (10%), blood (5%), surgical (5%), gastrointestinal (2%), or unknown (1%). Twenty (14%) isolates were multi-drug resistant; 6 (4%) were extensively drug resistant. Empiric antimicrobial therapy was effective in 97 (69%) cases. Liver disease (adjusted OR [aOR] 6.2, 95% CI 1.5 to 25.7; p = 0.01), malignancy (aOR 5.0, 95% CI 1.5 to 17.3; p = 0.01), and higher APACHE II score (aOR 1.1, 95% CI 1.0 to 1.1; p = 0.02) were independently associated with 30-day mortality.

Conclusions: PA infection in ICU is most commonly respiratory and associated with substantial mortality. Existing malignancy, liver disease, and higher APACHE II score were independently associated with mortality.