Population-based study of the epidemiology and the risk factors for pseudomonas aeruginosa bloodstream infection

Background: : Detailed population-based data on the epidemiologyof Pseudomonas aeruginosa bloodstream infectionsare sparse. We sought to describe the incidence rate, riskfactors, and outcomes associated with P. aeruginosa bacteremiain a large Canadian health region. Patients and Methods: : A retrospective population-basedsurveillance for P. aeruginosa bacteremia was conductedin the Calgary Health Region (CHR, population:approx. 1.2 million) during the period from 2000 to2006. Results: : A total of 284 incident cases of P. aeruginosabacteremia were identified in CHR residents, correspondingto an annual incidence rate of 3.6/100,000.Nosocomial acquisition accounted for 45% of cases,healthcare-associated community onset for 34% of cases,and community-acquired (CA) cases for 21%. Relative tothe general population, risk factors for bloodstreaminfection included male sex, increasing age, hemodialysis,solid organ transplant, diagnosis of cancer, heartdisease, HIV infection, diabetes mellitus, and/or chronicobstructive airway disease (COPD). Overall mortality was 29%. Factors associated with mortality in univariateanalysis included pulmonary focus of infection andco-morbidities, including chronic liver disease, substanceabuse, heart disease, COPD, and cancer, and increasedwith the burden of co-morbidities. Despite thosepatients with CA disease having fewer co-morbidities,they had a significantly higher mortality rate thaneither healthcare-associated cases or nosocomial cases(RR 1.88, p = 0.05). Conclusions: : This study documents that P. aeruginosabacteremic disease is responsible for a significant burdenof illness in general populations and identifies thosegroups at increased risk of infection and subsequentmortality. This information can be used to identify thoseindividuals likely to benefit from empiric anti-pseudomonaltherapies.