Evolution over a 15-year period of clinical characteristics and outcomes of critically ill patients with community-acquired bacteremia

Abstract

Objective: In recent years, outcomes for critically ill patients with severe sepsis have improved; however, no data have been reported about the outcome of patients admitted for community-acquired bacteremia. We aimed to analyze the changes in the prevalence, characteristics, and outcome of critically ill patients with community-acquired bacteremia over the past 15 yrs.

Design: A secondary analysis of prospective cohort studies in critically ill patients in three annual periods (1993, 1998, and 2007).

Setting: Forty-seven ICUs at secondary and tertiary care hospitals.

Patients: All adults admitted to the participating ICUs with at least one true-positive blood culture finding within the first 48 hrs of admission.

Interventions: None.

Measurements and main results: A total of 829 patients was diagnosed with community-acquired bacteremia during the study periods (148, 196, and 485 in the three periods). The prevalence density rate of community-acquired bacteremia increased from nine per 1000 ICU admissions in 1993 to 24.4 episodes per 1,000 ICU admissions in 2007 (p < 0.001). The prevalence of septic shock also increased from 4.6 episodes/1,000 admissions in 1993 to 14.6 episodes/1,000 admissions in 2007 (p < 0.001). Patients with community-acquired bacteremia were significantly older and had more comorbidities. No significant differences were observed in the presence of Gram-positive and Gram-negative micro-organisms among the three study periods. Mortality related to community-acquired bacteremia decreased over the three study periods: 42%, 32.2%, and 22.9% in 1993, 1998, and 2007, respectively (p < 0.01). The occurrence of septic shock and the number of comorbidities were independently associated with worse outcome. Appropriate antibiotic therapy and development of community-acquired bacteremia in 1998 and 2007 were independently associated with better survival.

Conclusions: The prevalence of community-acquired bacteremia in ICU patients has increased. Despite a higher percentage of more severe and older patients, the mortality associated with community-acquired bacteremia decreased. Improved management of severe sepsis might explain the improvements in outcomes.