Delayed insertion of blood culture bottles into automated continuously monitoring blood culture systems increases the time from blood sample collection to the detection of microorganisms in bacteremic patients.

This study examined the effects on patients with bacteremia of delaying the insertion of a blood culture bottle into an automated, continuously monitoring blood culture system. We investigated the time taken from the collection of blood samples (collection) to the insertion of blood culture bottles inoculated with blood samples into the instrument (insertion), and compared the mean detection time from collection to a positive signal from the instrument with the time between collection and insertion. The study was conducted from January 2003 to December 2004 at Kyoto University Hospital. Insertion into the system on the day of blood sample collection was defined as same-day insertion, and insertion on a different day to collection was defined as delayed insertion. The 7394 aerobic and anaerobic blood culture bottle sets obtained during the study period included 4361 sets with same-day insertion and 3033 sets with delayed insertion. For same-day insertion, 458 microorganisms were isolated from 432 positive sets in which at least one blood culture bottle was positive. For delayed insertion, 405 microorganisms were isolated from 379 positive sets in which at least one blood culture bottle was positive. The mean detection time for all microorganisms was significantly earlier for same-day insertion than for delayed insertion (28.3 h vs. 45.0 h, respectively, P < 0.0001). Delays from collection to insertion affect the time from collection to the detection of microorganisms.