Effects of Preincubating Blood Culture Bottles at 37℃ during the Night Shift and of Collected Blood Volume on Time to Detection and Days to Final Report

Abstract

Background: By varying the collected blood volume and storage temperature of the blood culture bottles prior to entry in an automated blood culture system, growth of organisms will be affected. Methods: Blood culture bottles with a 20 mL blood volume per set were stored at 37oC (1st period) and room temperature (RT, 2nd period) upon arrival at the laboratory after working hours compared to baseline period (10 mL, RT). The time to detection (TTD) for all strains and the number of days until the final report after bottle entry were compared among the three periods. Results: The median TTD for all strains was 13.5 h, 10.6 h, and 11.3 h in the baseline (N=268), 1st (N=454), and 2nd period (N=370), respectively (P＜0.001). The final identification report was available within two days of bottle entry for 12.3%, 30.6% and 15.1% of bottles in the three different periods, respectively (P＜0.001). Conclusion: Collecting an adequate blood volume is critical to reduce TTD. The preincubation of blood culture bottles at 37oC during the night shift might enable earlier final reports than storage at RT for samples with the same collected blood volume. (Ann Clin Microbiol 2014;17:14-19)