Routine blood culture collection for nonelective ICU admissions resulted in increased detection of bloodstream infections in a recent study.
Researchers in the Netherlands performed a before-after analysis of patients admitted to a tertiary care hospital's ICU between January 2015 and December 2018. On Jan. 1, 2017, automatic orders were implemented to collect a single set of blood cultures for each patient immediately upon ICU admission. The researchers compared blood culture results and contaminated blood cultures for 2015 to 2016 (the before period) and 2017 to 2018 (the after period). Any positive blood cultures were classified as bloodstream infection or contamination. The results were published Nov. 9 by Critical Care Medicine.
Overall, blood cultures were obtained in 573 of 1,775 patients (32.3%) in the before period and in 1,582 of 1,871 patients (84.5%) in the after period (P<0.0001). Mean age was 61 years, and most patients (61.4% in the before group and 63.2% in the after group) were men. Bloodstream infection diagnoses increased, from 95 patients (5.4%) in the before group to 154 patients (8.2%) in the after group (relative risk, 1.5; 95% CI, 1.2 to 2.0; P=0.0006). Based on the average number of blood cultures obtained per patient, an estimated 1,009 additional cultures were obtained in the after period. This yielded 59 bloodstream infections, corresponding to a number needed to culture of 17 to detect one additional infected patient. Forty patients in the before group (2.3%) and 180 patients in the after group (9.6%) had blood culture contamination (relative risk, 4.3; 95% CI, 3.0 to 6.0; P<0.0001). No difference was seen in rate of vancomycin use or presumed episodes of catheter-related bloodstream infections treated with antibiotics between the study periods.
Among other limitations, the authors noted that they did not collect information on vancomycin use or catheter-related bloodstream infections after patients' ICU stays and that their increased detection of bloodstream infection was caused by low adherence to sepsis guidelines, meaning their findings may not be generalizable to settings with better adherence. They concluded that in a setting where blood culture collection for clinically suspected infection was suboptimal, universal cultures for ICU admissions increased detection of bloodstream infections as well as the proportion of patients with contaminated blood cultures, without increasing vancomycin use in the ICU. “Our findings illustrate the potential effect of obtaining blood cultures in every critically ill patient, even when a clinical suspicion of infection is not (yet) obvious,” they wrote.