Reducing Blood Culture Contamination Rates: Experiences of Four Hospital Systems

Blood cultures (BCs) are one of the most common tests performed for the evaluation of patients with suspected bloodstream infections. Numerous studies show that the false positivity rate of BCs, i.e., contaminated BCs, varies across institutions, ranging from 0.6–12.5% [1]. False-positive BCs may have negative consequences for patients including delayed diagnosis, unnecessary use of antimicrobial agents, increased length of hospitalization, additional laboratory testing, and increased overall healthcare costs [2‐6]. Similar issues are apparent in the pediatric population with high BC contamination (BCC) rates and downstream effects [7]. Even though there have been several studies and meta-analyses highlighting interventions that have successfully reduced false-positive results [1, 8‐17], institutions continue to face unacceptable BCC rates. Here, we report experiences of four major US hospital systems that successfully reduced their high rate of BCC with the introduction of a multidisciplinary change team, and comprehensive and creative educational programs, along with data sharing, training, retraining, and a plan to sustain reduced BCC rates.

Results of BCC interventions at Hospital A and C have been published in part [18‐21].

Four hospital systems (A–D) independently planned an intervention(s) to reduce BCC that was specific for their facility based on assessment of historic BC surveillance data, review of their processes, and compliance with their hospital policies. These plans were spearheaded by a collaborative, multidisciplinary team of stakeholders to lower their pre-intervention BCC rates. Per each institution’s BC policy, 2% chlorhexidine product and 70% isopropyl alcohol were used for skin and BC bottle septum disinfection, respectively, followed by collection of two or more BC sets (i.e., one aerobic and one anaerobic bottle per set) from separate peripheral venipuncture sites, newly inserted IV catheters, or line draws when clinically indicated. Hospital C used a diversion tube along with skin disinfection when collecting BCs. Blood culture diversion tubes divert the first 1–2 ml of blood to remove potential skin contaminants from entering the BC bottle [22]. All institutions used BD BACTEC™ Blood Culture media (BD, Sparks, MD), and inoculated BC bottles were incubated and monitored using the automated BD BACTEC™ FX system. All hospitals complied with the College of American Pathologists certification requirement to perform BCC surveillance and determine their contamination rates [8, 23]. A standard definition of a contaminant due to skin flora was used at each institution, i.e., coagulase-negative staphylococcus, Bacillus species, not B. anthracis., Corynebacterium spp., Cutibacterium spp., viridans group streptococcus, and Micrococcus spp. in a single BC bottle or set, out of two or more sets within 24 h of collection [8, 17, 23]. At least two sets (i.e., 4 bottles) had to be obtained to define BCC. Hospital D also included saprophytic Neisseria sp. and Moraxella sp. in their definition of a contaminant. The institutions’ BCC rate was determined by the number of contaminated cultures during a given time divided by the total number of cultures performed during the same given time. Hospitals A and B were able to identify individual collectors using codes or names to establish who needed retraining because of repeat BCC. Hospitals C and D monitored contamination by location where the BCs were drawn. BC surveillance data were acquired through their information technology (IT) system and shared on a monthly basis with key stakeholders (e.g., Infection Control, Pharmacy & Therapeutic and Antimicrobial Stewardship committees, Emergency Department (ED), and phlebotomy manager and staff except for Hospital B who collected data manually and Hospital C who shared information on a quarterly basis.

Table 1 lists hospitals A–D, their demographics, phlebotomy staff, and annual number of BCs processed.

Table 2 identifies the elements of each phase of their intervention led by a multidisciplinary team. Initially, the leadership team assessed historical BCC surveillance data, their current process, where the intervention should occur, and, at some institutions, other issues such as staffing and length of the intervention. Subsequently, they developed an action plan for education and training based on their hospital’s approved BC collection policy. Finally, they reviewed results comparing their pre- and post-intervention data, key factors that contributed to a successful intervention, and what worked and what did not as part of their sustainment plan.

For statistical analysis, Fisher’s exact test was used to compare BCC rates from one time period to another (GraphPad Prism version 7, GraphPad Software, San Diego, CA).

Laboratories are challenged to provide a value-based service that includes accurate, rapid, and clinically meaningful results that lead to improved patient care while supporting their antimicrobial stewardship program. Several studies and meta-analyses have described successful interventions using dedicated phlebotomy teams, sterile gloves and processes, collection kits, and diversion devices to decrease BCC rates [1, 5, 8‐10, 12, 14‐17, 24]; however, we still do not have one intervention or combination of interventions that has been universally accepted to decrease BCC rates [10, 11, 14]. Perhaps we need national regulations by the Center for Medicare and Medicaid Services (CMS) as part of their Quality Measurement Program to develop a requirement for all healthcare facilities involved in BC collection to develop a BC Stewardship Program [25].

What is an acceptable BCC rate? Many institutions use ≤ 3.0% BCC as their benchmark for an acceptable BCC rate, although there does not appear to be documentation as to where or how this level was derived [5, 8, 26]. It is clear from the results obtained from our four hospital systems and from the literature [14] that BCCs of much less than 3% are achievable and sustainable by both laboratory and nursing employees collecting BC samples. Based on our results, we propose a new achievable and sustainable BC contamination rate benchmark of 1.5 to < 2%.

Our report is based on results obtained from four independent studies performed by major healthcare systems representing > 166,774 BCs per year collected predominantly from adults by nurses and phlebotomists. Although several intervention options, e.g., collection kits and sterile gloves, were introduced early on by Hospital A to lower their contamination rates, they did not experience sustained success until they utilized a multidisciplinary team approach to lower rates based upon education, feedback, accountability, and sustainable training to maintain rates significantly < 0.35–1.19% [20, 21].

Another option that might have been helpful is the use of the TeamSTEPPS™ evidenced-based program developed by the Department of Defense and the Agency for Healthcare Research and Quality (AHRQ) and introduced in 1996 by CMS to provide guidance for successful interventions [27]. TeamSTEPPS™ has been implemented by healthcare professionals throughout the USA and internationally to: improve patient safety and health care teamwork skills. The program provides a toolkit for introducing a readiness assessment, detailed plan for training and implementation of an intervention, and sustainment of successes. Although the hospitals reported here did not use the TeamSTEPPS™ toolkit, aspects of each phase of this program were used as in a previously reported study [16].

A key to the success of an improvement program is the development of a multidisciplinary change team as recommended in the TeamSTEPPS™ program comprised of (1) an executive leader who provides the clout to bring about change and authority to allocate resources, motivate, and support the team, (2) clinical and technical champions who are knowledgeable, understand processes, have an interest in driving change, and can serve as instructors and coaches, and (3) front-line leaders who understand the organizational detail, can effect change, and oversee data collection and assure changes are measured [28]. Each of the four hospitals presented here developed their own plan based on resources and needs assessment for decreasing BCC, but all of them used a multidisciplinary team approach. An assessment of historical pre-intervention BCC surveillance data provided the necessary information for each hospital to set a goal to decrease contamination rates as low as possible, target where the intervention would occur, i.e., the ED or hospital-wide, and confirm the readiness of their target site based on staffing and other activities that might side track the intervention. Several publications have targeted the ED where BCC is frequently highest [3, 9, 16, 24, 29]. Two of the four reporting hospitals also targeted the ED (Hospital C and D), while the other hospitals took a whole-hospital approach. Although we focused our attention on reducing BCC rates for peripherally obtained BCs, one of the centers, Hospital D, also addressed line draw BCCs (see Hospital D results above).

Although there are no guidelines for the determination of line- or catheter-associated BCC, Hospital D was able to determine which BCs collected were from peripheral or line access. They used the same definition of blood culture contamination for both processes. After education, feedback, and limiting line draws, the contamination rates for line collection fell from > 7 to 1.2% and were maintained at levels ≤ 2%. In a meta-analysis performed by Snyder et al. [1], they found that typically, the contamination rates are much higher in line (catheter) collection than in venipuncture.

Often the collection through catheters offers advantages including reduced needle sticks, ease of collection, and patient comfort; also, for difficult collections, it offers a method to rapidly obtain BCs [30]. Recommendations for collections of line cultures include a collection of a second culture from a venipuncture site to compare growth to aid in determining true infections from contaminants [31]. The Infectious Disease Society of America supports this recommendation when collecting BCs from central lines [32]. The evaluation of critically ill and immunosuppressed patients is difficult. Clearly the specificity of line draws is lower than that of peripheral collections, and additional BCs are needed to determine a true bacteremia from contamination or line colonization [10, 33]. Care must be taken in evaluating BC results that contain organisms associated with contamination. Upon reviewing results from BCs with coagulase-negative staphylococci by a team of infectious disease specialists, they concluded that as much as 85% of these isolates were contaminants [10, 32].

All locations were deemed ready for an intervention initiative to accomplish their goal. Each hospital followed an action plan for the implementation of their intervention using an approved BC collection policy as the foundation for their educational and training programs. Intervention success was measured by comparing pre- and post-intervention data.

Whereas many studies highlight the use of collection kits, diversion devices, sterile gloves, processes, dedicated phlebotomy teams, etc., the successful experiences presented here by four major hospital systems are based on just a few key elements for changing the tide in each of their hospital systems without additional staff. We conclude by using continuous monitoring, appropriate feedback, accountability of collectors, and continued education, well-trained nurses and laboratory phlebotomists alike can achieve low BCC rates. The last and perhaps most important phase of implementing a successful intervention, and in the opinion of the authors the phase most often neglected, is the development of a plan for sustainment. Often hospitals experience success, albeit not long-lived. Without continual training, retraining, and updating the intervention, nurse and laboratory phlebotomists may become disengaged because of high work volumes and changes that overshadow their willingness to follow the BC policy without exception.

Hospitals A–D all engaged in independent PI interventions based on their unique needs that reflect real-world experiences rather than participating in a single study at four sites. The results and recommendations refer only to peripherally drawn BCs and contamination rates.

We report the steps used by each of four hospital systems based on their resources and needs assessment to decrease their high BCC rates. From this information, we extracted aspects of each plan that were common to most if not all hospitals to establish a list of key factors contributing to a successful and sustained intervention. We propose a new benchmark for BCC of 1.5 to < 2%, which is achievable and sustainable based on our experiences. Other healthcare facilities may find the plans and list of key factors useful in developing their own unique plan to achieve similar successes.