Impact of Blood Cultures Drawn From Arterial Lines on the Incidence of Contamination, Detection of Bacteremia, and Blood Culture Volume: an Observational Study

Taking blood cultures is an important and very common procedure in intensive care units due to the high incidence of sepsis and the need for rapid and accurate identification of bacteremia. However, despite the importance of taking a sufficient volume of blood for the purpose of identifying bacterial growth in the blood, the average blood volume in blood cultures at our institution ranges from 3.5-4 ml per bottle (where the desired volume is 10 ml). Taking an insufficient amount of blood reduces the ability of the bacteriological laboratory to detect bacterial growth and thus may lead to a delay or missed diagnosis of bacteremia, identification of the pathogen, and adjustment of appropriate treatment according to sensitivities.

In intensive care units, most patients are monitored using an arterial catheter, which allows for frequent blood tests without the need to puncture the patient. Following recently published studies that showed that there is no significant difference in the incidence of contamination when taking blood cultures from an arterial catheter compared to a peripheral vein puncture, and in order to improve our ability to identify bacteremia, it was decided to implement a new protocol in the General Intensive Care Unit that includes taking blood cultures from an arterial catheter. According to the new protocol, it was decided that when taking blood cultures from a patient with an arterial catheter, one pair of cultures should be taken from the arterial catheter and another pair from a peripheral vein puncture.

In this study, we would like to examine the contamination rate of blood cultures, the identification of true bacteremia, and the collection of appropriate blood volume and number of blood specimens taken in patients hospitalized in the General Intensive Care Unit at our institution, while analyzing differences between the period before the implementation of the new protocol and the period after the implementation, and differences between cultures taken from an arterial catheter and from a peripheral vein puncture.