Evaluation of a four-day incubation protocol for blood cultures: a quality improvement project

Blood cultures are critical in diagnosing bloodstream infections and guiding the treatment of sepsis, which carries a significant mortality risk. Traditional blood culture protocols often recommend a five-day incubation period to ensure the recovery of clinically significant pathogens. However, recent evidence suggests that a shorter incubation period may be sufficient, potentially reducing laboratory workload and the recovery of contaminants. Methods This quality improvement project was conducted to evaluate the performance of a four-day incubation protocol using the BD BACTEC automated blood culture system in a large academic center with over 1,000 beds, processing more than 70,000 blood culture requests annually. A retrospective analysis was performed on 71,862 blood cultures processed in 2022. Results Results indicated that 99.2% of all positive cultures, including those in pediatric cases, were detected within four days, with a mean time to positivity of 23.97 h. Only 0.8% of blood cultures flagged positive after the four-day mark, and these were predominantly cases with previous positive cultures or repeat cultures that did not alter patient management. Conclusion We conclude that a four-day incubation period is sufficient for the detection of clinically significant pathogens using the BD BACTEC system. This change not only optimizes laboratory operations by increasing capacity and reducing waste but also supports timely clinical decision-making.