Reducing Blood Culture Contamination; a Quality Improvement Project in Emergency Department
Authors: Gupta Itisha , Codd Jane 
Published: November 2020

Background: Blood culture is an important investigation in diagnosing sepsis. Positive culture helps to tailor therapy and is crucial in antimicrobial stewardship (AMS). However, positive blood culture does not always denote a bloodstream infection. Sometimes, false-positive results occur because of contamination from organisms outside the bloodstream, leading to significant negative consequences to patient treatment decisions and financial implications. Rates of blood culture contamination vary widely (0.6%–6%) between organizations, and although it is very difficult to eliminate contamination, it can be minimized. Our hospital group has multiple sites including emergency departments (EDs). We have been intermittently monitoring blood culture contamination rates since 2008, which decreased from 6.8% to 4.8% in 2009 but remained static when audited in 2010, 2012, and 2015. Objectives: To reduce our blood culture contamination rate further by targeting 2 busy EDs and by introducing continuous surveillance of blood culture contamination across 3 hospitals beginning in April 2016. Methods: In 2015, for the first time, blood culture contamination rates for both EDs, based in 2 different hospitals, were calculated. The ED results were communicated to the healthcare workers (HCWs), who agreed to establish a continuous surveillance of blood culture contamination and to participate in a reduction plan. Competency training was conducted according to training needs analysis. For example, phlebotomists were trained to ensure the use of the appropriate blood culture kit and educational sessions were tailored to staff groups. The blood culture contamination rate was monitored from April 2016 to March 2019 for 3 hospitals and both EDs to determine the impact of various measures introduced during this time. Results: In 2015, contamination rate of the 3 hospitals was 4.07%, and 10.2% of total blood cultures flagged positive. Also, 25% of blood cultures were requested from Eds, but these samples comprised 54% of the total contamination. The contamination rates for EDs A and B were 7.4% and 10.6%, respectively, which were significantly higher than the overall rate. From April 16 to March 19, there was 22% increase in total blood cultures performed. Results were analyzed quarterly. In total, 8,525 blood culture sets were received in January–March 2019; of these, the EDs contributed 2,799 sets (32.8%). The total blood culture contamination rate in January–March 2019 decreased to 3.1%. Both EDs A and B showed decreases in their contamination rates to 5.5% and 7.4%, respectively, in 2018–2019. The quarterly decreases were 5.2% and 4.9% in January–March 2019. Conclusions: The emphasis on the sepsis pathway probably led to year-on-year increases in total blood culture sets. Both ED blood culture contamination rates decreased. Consistent efforts in education, training, ensuring competency to various HCW groups, and provision of adequate blood culture kits are important for sustaining these improvements.

Funding: None

Disclosures: None