Blood Culture Incubation Period – A QI Project
Submitted by Dr. Johan Delport, Program Head Microbiology
Every winter, our microbiology laboratory experiences a surge in blood culture specimens. This poses a capacity challenge to our incubators which detect positive cultures. To meet this demand without purchasing new equipment, the microbiology team under the leadership of Dr. Almutawa explored a more efficient approach to blood culture incubation. Traditionally, a five-day incubation period is recommended, but recent studies indicate that a four-day protocol may be sufficient.
As part of a quality improvement project, we analyzed over 70,000 blood cultures from 2022 to assess whether we could safely shorten the incubation period. Our analysis revealed that more than 99% of positive cultures were detected within the first four days, with an average detection time of 23 hours. Blood cultures that flagged positive on the fifth day were typically repeat positives with the same organism or contaminants that did not affect patient care. Based on these findings, we implemented the four-day protocol in 2024.
Eight months later, a review of the data showed no significant differences in positivity rates or average time to detection. The shorter protocol offers potential benefits for patient care by reducing unnecessary treatments for contaminants, minimizing repeat cultures, and supporting timely discharges. Additionally, this change reduces lab costs associated with processing cultures that are not clinically significant and improves overall efficiency, enabling us to continue delivering high-quality care during peak seasons.
