CLN - Bench Matters
Blood culture contamination (BCC) remains one of the most persistent preanalytical challenges in clinical microbiology. It directly affects patient outcomes, antimicrobial stewardship, and healthcare costs (1, 2). Even small increases in contamination rates can result in misdiagnosis of bloodstream infections, unnecessary antibiotic exposure, and prolonged hospital stays (2, 3). National benchmarks recommend contamination rates of ≤3%, with ≤1% considered optimal in high-performing laboratories (1). This article describes a process improvement initiative implemented by our laboratory team at Baptist Memorial Health Care aimed at reducing BCC through staff education, workflow standardization, and reinforcement of evidence-based collection practices. The intervention highlights the role of laboratory leadership in strengthening diagnostic stewardship and improving preanalytical quality.
Blood cultures remain the gold standard for diagnosing bacteremia and sepsis. However, their clinical utility is highly dependent on proper specimen collection technique (2). BCC occurs when skin flora or environmental organisms are introduced into the culture bottle during collection, producing false-positive results that may be misinterpreted as true infection (3). Contaminated blood cultures lead to unnecessary antimicrobial therapy, additional diagnostic testing, and increased length of hospital stay (2, 4). These outcomes negatively affect patient safety and increase healthcare costs (4). The Clinical and Laboratory Standards Institute (CLSI) and the Centers for Disease Control and Prevention emphasize that most contamination events happen because of preventable preanalytical errors (1, 5).
Additionally, studies demonstrate that contamination rates above 3% are associated with significant clinical and financial burden, which reinforces the need for continuous quality improvement and standardized collection practices (1, 4).
Internal quality monitoring at our institution identified BCC rates that exceeded institutional targets. A gap analysis revealed inconsistent collection techniques, variability in skin antisepsis practices, and differences in competency across personnel responsible for specimen collection. The improvement initiative that we subsequently undertook led to sustained BCC reduction, with the facility consistently maintaining BCC rates below 1% and reaching a low of 0.36%.
Key contributing factors to BCC included:
These findings are consistent with national literature, which identifies decentralized blood culture collection systems as a major contributor to elevated contamination rates.
The laboratory team implemented an intervention plan to address increased contamination rates. The plan included three key parts.
Following implementation of the intervention bundle, BCC rates demonstrated a sustained downward trend over subsequent reporting periods. Observed outcomes included:
Beyond quantitative improvements, staff demonstrated increased awareness of preanalytical quality and its impact on patient outcomes.
BCC is a preventable, system-level patient safety issue rather than an isolated laboratory error (2, 4). The majority of contamination originates during specimen collection, which makes preanalytical intervention the most effective control point (3). Evidence supports bundled interventions combining education, antiseptic optimization, and performance feedback as the most effective strategy for sustained improvement (4, 6). Single interventions alone rarely produce long-term change. From a leadership perspective, laboratory managers play a central role in diagnostic stewardship by aligning clinical collection practices with laboratory quality standards.
Strengthening interdisciplinary communication ensures consistent expectations and accountability across departments (4). Reducing contamination also supports antimicrobial stewardship by preventing unnecessary antibiotic exposure, minimizing resistance risk, and improving diagnostic accuracy in suspected sepsis cases (2, 4).
Sustained reduction in BCC requires a structured, multifaceted approach involving education, standardization, and continuous feedback. This project demonstrates that laboratory-led quality improvement initiatives can significantly improve preanalytical performance and patient safety outcomes. Ongoing monitoring and reinforcement are also essential to maintaining gains and ensuring long-term success in diagnostic stewardship.
Interested in learning more? Attend the ADLM 2026 roundtable, “Blood culture contamination rates: Collaboration for sustainable improvements,” on Monday, July 27 in Anaheim, California.
I’Esha Bowens, MHA, MLS (AMT), is a laboratory manager at Baptist Memorial Health Care in Oxford, Mississippi. +Email: [email protected]