Gram-negative bacteremia upon hospital admission: when should Pseudomonas aeruginosa be suspected?

Area of Science:

• Infectious Diseases
• Clinical Microbiology
• Epidemiology

Background:

• Pseudomonas aeruginosa is an infrequent cause of community-acquired bacteremia, particularly in non-immunocompromised individuals.
• Clinical decisions regarding empirical anti-pseudomonal therapy are challenging due to the need to balance judicious antibiotic use with timely treatment.
• There is a need for improved guidance to identify patients at risk for P. aeruginosa bacteremia upon hospital admission.

Purpose of the Study:

• To determine the incidence of P. aeruginosa bacteremia at hospital admission.
• To develop a predictive model for identifying patients with P. aeruginosa bacteremia.

Main Methods:

• A retrospective study was conducted across four tertiary care hospitals.
• Microbiology databases were searched for Gram-negative rod (GNR) bacteremia within 48 hours of admission.
• Logistic regression analysis identified independent predictors of P. aeruginosa bacteremia.

Main Results:

• P. aeruginosa accounted for 6.8% of GNR bacteremia episodes at admission (5 cases per 10,000 admissions).
• Independent predictors included severe immunodeficiency, age >90 years, recent antimicrobial therapy, and presence of central venous or urinary devices.
• In patients without severe immunodeficiency, the risk of P. aeruginosa bacteremia increased from 1:42 to nearly 1:3 with two or more predictors.

Conclusions:

• P. aeruginosa bacteremia at hospital admission is uncommon in patients without severe immunodeficiency.
• Empirical anti-pseudomonal treatment is recommended for immunocompetent patients with suspected GNR bacteremia and two or more identified predictors.