Shortening Blood Culture Incubation Times Evaluation of Optimal Incubation Time for a Fully Automated Blood Culture System in the Clinical Laboratory

The increased sensitivity of blood culture monitoring systems to detect growth has played an increasingly important role in the time to detection over the past few decades. The objective of this study was to determine the optimal incubation duration that, while maintaining sensitivity, might reduce false positive blood culture occurrences and shorten the total incubation time. We retrospectively reviewed data on positive blood cultures from the BACT/ALERT VIRTUO Microbial Detection System between January 2021 and December 2021. True positive and contaminant blood cultures were identified by reviewing the patient data from the laboratory information system. Based on the time to detection, the true positives and contaminants recovered from day 1 through day 5 were sorted, and the percentage for each day was calculated. During the study period, 977 (8.8%) out of 11,102 loaded bottles were flagged positive. On day 4, the contamination rate (2.6%) was higher than that of the true positive (0.89%). The true positives and the contaminants recovered on day 4 (P < 0.05) were significantly lower than on day 3. As no isolates were recovered on day 5, reducing the incubation time to 4 days would not affect the clinical decision making.