The Diagnostic Yield of Routine Admission Blood Cultures in Critically Ill Patients

Objectives: Although the Surviving Sepsis Campaign bundle recommends obtaining blood cultures within 1 hour of sepsis recognition, adherence is suboptimal in many settings. We, therefore, implemented routine blood culture collection for all nonelective ICU admissions (regardless of infection suspicion) and evaluated its diagnostic yield.

Design: A before-after analysis.

Setting: A mixed-ICU of a tertiary care hospital in the Netherlands.

Patients: Patients acutely admitted to the ICU between January 2015 and December 2018.

Measurements and main results: Automatic orders for collecting a single set of blood cultures immediately upon ICU admission were implemented on January 1, 2017. Blood culture results and the impact of contaminated blood cultures were compared for 2015-2016 (before period) and 2017-2018 (after period). Positive blood cultures were categorized as bloodstream infection or contamination. Blood cultures were obtained in 573 of 1,775 patients (32.3%) and in 1,582 of 1,871 patients (84.5%) in the before and after periods, respectively (p < 0.0001), and bloodstream infection was diagnosed in 95 patients (5.4%) and 154 patients (8.2%) in both study periods (relative risk 1.5; 95% CI 1.2-2.0; p = 0.0006). The estimated number needed to culture for one additional patient with bloodstream infection was 17. Blood culture contamination occurred in 40 patients (2.3%) and 180 patients (9.6%) in the before period and after period, respectively (relative risk 4.3; 95% CI 3.0-6.0; p < 0.0001). Rate of vancomycin use or presumed episodes of catheter-related bloodstream infections treated with antibiotics did not differ between both study periods.

Conclusions: Implementation of routine blood cultures was associated with a 1.5-fold increase of detected bloodstream infection. The 4.3-fold increase in contaminated blood cultures was not associated with an increase in vancomycin use in the ICU.