Reducing False-Positive Blood Cultures in Adult A&E using a Initial Specimen Diversion Device

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Jane Hodson, James Stebbing, Catherine Graham and Siobhan O’ Donnell
Guy’s and St. Thomas’ NHS Foundation Trust, London, England

Introduction
Blood cultures are the gold standard for obtaining important diagnostic information to enable detection of the presence of a bacteraemia. The Clinical and Laboratory Standards Institute recommend that hospitals achieve a contamination rate of   <3%1 though rates are estimated to range from 2% to over 10%. Economically false positive blood culture results are estimated to cost between £2,000 – £4,200 and have a significant negative impact on patients1. These costs include delays in diagnosis, unnecessary administration of intravenous antibiotics, increased risk of complications related to unnecessary intravenous cannulation, unplanned removal of central venous access devices, additional laboratory testing, and delayed discharge by 2 days2 resulting in an overall increase in the cost of hospitalisation. Additionally, there are time and costs pressures associated with the manpower required to investigate each false positive blood culture. In our trust the contamination rate of blood cultures has consistently averaged 6% for many years despite prior quality improvement projects that included the introduction of blood culture collection packs and refresher training on how to take a blood culture at every new doctor induction. The highest number of contaminated specimens are associated with A & E. The use of a cannula for blood culture sampling is associated with increased risk of contamination1 and against our Trust intravenous access guideline. Despite this, we are aware, through bacteraemia investigations, that in A & E, blood cultures are taken from cannulae. Our project was to determine if the introduction of an initial specimen diversionary device (ISDD) that automatically side-line’s the first flash of blood during the routine process of drawing a blood culture will reduce the number of false positives in this department.

Methods

  • The diversionary device was introduced into our central London A & E that sees 400 -450 patients / day.
  • Introduction and training on the use of the device was provided at weekly early morning educational sessions by the company
  • The ISDD diverts the first 0.15 ml of blood that may contain skin contaminants and “locks” it into a small chamber is available in two versions: a traditional style butterfly needle and an extension set that attaches to an intravenous cannula (Images 1 and 2)
  • The ISDD was the only change in practice implemented for the duration of the study
  • The PDN and 2 research nurses provided ongoing support and promotion of the project
  • All A & E staff members were involved in the study
  • The current phlebotomy equipment was removed from the cannulation trolleys located across the adult A & E
  • Bags containing all the equipment required for blood culture collection were prepared by the department research nurses and centrally located at the staff desk in Majors
  • Data collection was totally anonymised with the only question asked, on a form included in the bag, was if the blood culture was taken from a cannula or using a butterfly
  • Staff members collected a bag prior to taking a blood culture then returned the completed form to a box co – located with the equipment
  • The completed forms were collected weekly and the data reviewed to determine the number of contaminated samples
  • The project is reaching its conclusion and the final results will be reviewed by a Trust microbiologist, an A & E research consultant and the Lead IV Practitioner representing Infection Prevention and Control

Results

  • The project has run over 5 months, May -Sept 2021
  • Data has been collected on approximately 500 specimens using the ISDD
  • The initial calculation demonstrates that the current contamination rate is <2%
  • An overall reduction of 66%
  • There was no difference in the rate of false positive results between the cultures taken from a cannula and those done from a direct stab using a butterfly.

Discussion
The project has demonstrated a significant reduction in the number of false – positive blood cultures using the ISDD.  The staff in A & E embraced the project. They found the ISDD very simple to use as it required no change in their current practice. The results of the weekly data collection was fed back to the A & E research nurses to share with the department. The project made clear despite a cannula being used regularly for blood culture collection, use of the ISSD mitigated the increased risk of contamination. The decrease in false positives encouraged A & E staff to continue to use the ISDD.  All current stock has been used and they are eager to continue using the product.  A report on the project will be presented at the next Trust Infection Control Committee with a view to endorse adoption of the ISDD Trust – wide.  Initial plans for roll out are in the early stages.  Following on from A & E the adult intensive care unit will be the next department to adopt use of the device.  Further roll out to specialist areas will then follow.  Currently the ISDD is not available in a blood culture pack which is our current practice.  Plans are in place to include it in a pack as our usage increases. The ISDD as a stand alone item is expensive so the project was slow to start. Based on the estimated costs of a false – positive blood culture, savings are estimated to be £28 – 72K for this initial sample.  This has been an exciting project for all of those involved.  The reduction in contamination rates were evident from the beginning.  The ISDD has the potential to not only reduce false – positive blood culture contamination rates and thus generate savings for the Trust but also to have a positive impact for our patients in their hospital journey.

REFERENCES:
1 Dempsey C, Skoglund E, Muldrew KL, Garey KW Economic health care costs of blood culture contamination: A systematic review. American Journal of Infection Control 47 (2019) 963 -967
2 Geisler BP, Jilg N, Patton RG, Pietzsch JB Model to evaluate the impact of hospital hospital-based interventions targeting false-positive blood cultures on economic and clinical outcomes. Journal of Hospital Infection 102 (2019) 438 -444

Prospective Trial of Passive Diversion Device to Reduce Blood Culture Contamination

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Sami Arnaout MD1, Richard T Ellison III, MD FIDSA, FSHEA1, Thomas C Greenough MD1, Azalea Wedig BS, CIC1, Michael J Mitchell, MD1, Lauren St. John, B.Math2, and Shannon Stock Ph.D.2
1UMass Chan Medical School, Worcester, MA; 2College of the Holy Cross. Worcester, MA.

Researchers with the University of Massachusetts Chan Medical School documented a clinical study of Kurin blood culture collection sets at UMass Memorial Medical Center. The study summarized the trial data in two ways: when the product was intended to be used and when it was actually used, thereby estimating the role of clinician compliance in the device’s efficacy.

UMass Memorial Medical Center is a three-campus facility with two separate Emergency Departments (ED) based at the two campuses with inpatient units. One campus has a higher level of patient acuity and therefore historically has had much higher rates of blood culture contamination. Both ED sites were involved in the trial, with one ED using Kurin for ten weeks, while the other used their standard collection technique. After a wash out period, the two EDs switched roles.

Approximately 5600 cultures were collected during the trial and about half of those were drawn using a Kurin set. The “observed” contamination rate was reduced from 3% to 1.1% when Kurin was used, representing a 63% decrease. As would be expected, there was no change in true positive rates.

The researchers applied an estimated cost of $7,000 per contaminated culture, yielding a cost savings calculation of $1.8M attributable to the drop in the “observed” rate. Likewise, they reported an increased length of stay of 1.3 days per contaminated culture, which translated to 343 avoided hospital days per year.

Passive Engineering Controls Result in Sustained 66% Reduction in Blood Culture Contamination

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Monica Baxter, Carolyn Cook and Angie James from St. Mary’s Regional Medical Center, Russellville, AR.

Background
Blood culture testing is an important diagnostic tool in identifying the presence of microbes in the bloodstream. Tests are frequently contaminated, leading to false-positive results. Blood culture contamination can result in unnecessary antibiotic treatment, extended hospital length of stay, and patient exposure to hospital-acquired conditions.

Methods
St. Mary’s Regional Medical Center (SMRMC) in Russellville, Arkansas, struggled with blood-culture contamination rates, with an average of 6.8% from 2014 to 2018. Ongoing staff education yielded a reduction to an average of 5%. In an effort to reduce the contamination rates, our facility elected to try a novel specimen diversion device. Laboratory and emergency department (ED) staff were educated on the diversion device prior to the initiation of the trial period. Compliance with the diversion device averaged 70%–75% during the trial period. Monitoring of contaminations was added to our daily safety huddle to provide a quick turnaround time for false-positive education to specific clinical staff.

Results
The results were significant, with a decrease in contamination rates from 4.93% to 1.66%—a 66% reduction. Improved blood culture testing has several advantages: best practice for patient care is first and foremost, along with other financial benefits for the facility. Several articles have estimated the cost of a contaminated culture to be $3,000–$10,000 per event; SMRMC has adopting an estimated cost of $4,000. The number of cultures at our hospital averages ~4,400 per year, and these results suggest a savings of >$500,000 per year (as contaminations on an annual basis fell from 217 to 73). With this intervention, 144 patients were spared from receiving unnecessary antibiotics as a result of a false-positive blood culture testing.

Conclusions
We conducted a brief analysis to determine whether there was any obvious change in length of stay for patients with a false-positive blood culture compared to those with true negative results. In analyzing data for 3 different months, patients with contaminated cultures spent an average of 3.97 additional days in the facility. In conclusion, the implementation of this specimen diversion device significantly lowered our contamination rates, was integrated into practice, and has provided clinical and financial benefits.

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Preventing Blood Culture Contamination using a Novel Engineered Passive Blood Diversion Device

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Jared Sutton, MPH, CIC; Paula Fritsch, MPH, MT, CIC; Marybeth Moody, MT(ASCP), SM; Kesha Dinaro, MSN, RN, CEN; Clinton Holder, MD. Bayfront Health St. Petersburg, St. Petersburg, FL

Introduction
Blood culture contaminants lead to increased empirical antibiotics usage, contributing to antibiotic associated colitis, multi-drug resistant bacteria, and increased risks for drug interactions. Quality improvement programs have led to complex costly blood culture collection bundles, including sterile kits, blood diversion tubes, and advanced skin preps, all with the goal of reducing blood culture contaminants. Despite current interventions contamination continues to occur because bacteria reside deep in the dermis where antiseptics cannot penetrate. This study investigates the efficacy of an engineered passive blood diversion device in preventing blood culture contaminates.

Methods
This quasi-experimental study focused on blood cultures collected by phlebotomy and the emergency department between January and September 2017 (Pre: Jan – April, Post: May – September). The ratio of contamination was evaluated using a chi-square test at a 0.05 alpha level. The intervention was only indicated for vacutainer draws during the study period, but stratifying the pre-intervention data for vacutainer collections was not possible. For this reason, this study focuses on total blood culture contaminants, and not just vacutainer collections. Without stratification, the mentioned results are what a user could expect to reproduce in a “real world” scenario.

Results
Results from 4220 blood cultures were analyzed. The pre- intervention period included 1953 cultures with a contamination rate of 0.025, 95% CI [0.019, 0.033]. The post-intervention period included 2267 cultures and a contamination rate of 0.012, 95% CI [0.008, 0.017]. A chi-square statistic was calculated to examine if the intervention reduced blood culture contamination. The test was found to be statistically significant, X2(1, N = 2852) = 10.979, p < 0.05.

Intervention Design Variations

Blood Culture Contaminant Control Chart

Intervention Cost Analysis

Conclusion
The results suggest that there is a relationship between the proportion of a blood culture contaminants and the type of device used. This may be more apparent given that the intervention was not indicated for all types of blood draws during the study period. It appears that this product can potentially reduce blood culture contaminants, but more research is required.

Study Limitations

  • The studied intervention is not indicated for use for all types of blood draws.
  • Intervention was utilized in 50% of blood draws during the post intervention period.
  • During the first 3 months of post Intervention period, the trial device was not indicated for use in 8 out of 9 contaminated cultures.
  • In the post study period, the device was redesigned to allow for different types of blood cultures (ex. draws from a freshly placed IV).

Download a PDF of this study.

References:
Bekeris, Leonas G., et al. “Trends in blood culture contamination: A College of American Pathologists Q-Tracks study of 356 institutions.” Archives of Pathology and Laboratory Medicine 129.10 (2005): 1222-1225.

Garcia, Robert A., et al. “Multidisciplinary team review of best practices for collection and handling of blood cultures to determine effective interventions for increasing the yield of true-positive bacteremias, reducing contamination, and eliminating false-positive central line–associated bloodstream infections.” American journal of infection control 43.11 (2015): 1222-1237.

Hall, Keri K., and Jason A. Lyman. “Updated review of blood culture contamination.” Clinical microbiology reviews 19.4 (2006): 788-802.

Self, Wesley H., et al. “Cost analysis of strategies to reduce blood culture contamination in the emergency department: sterile collection kits and phlebotomy teams.” Infection Control & Hospital Epidemiology 35.8 (2014): 1021-1028.

Not Your “Average” ED: A CNS-Led Project That Reduced Blood Culture Contaminations in One Emergency Department to Below Expected Levels

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Michael Allain, MS, RN, ACNS-BC, CCRN, Crouse Hospital

At the 2018 National Association of Clinical Nurse Specialists Conference, Michael Allain, MS, RN, ACNS-BC, CCRN, emergency services clinical nurse specialist at Crouse Hospital in Syracuse, New York, presented results related to the use of a novel FDA-cleared blood culture collection device that diverts the initial aliquot of blood to help hospitals in their efforts to reduce contaminated blood cultures (CBCs)

According to Allain, contamination makes interpreting results difficult and can cost millions of dollars. To address the issue at Crouse, Allain, in conjunction with the hospital’s phlebotomy manager, implemented strategies to reduce contamination in 2012. They provided department-wide education, limited who drew blood cultures, and closely monitored compliance on monthly basis. The overall contamination rate from 2013-2016 ranged from 2.1% to 1.6%.

In January 2017, the CNS for the emergency department re-evaluated the current state of blood culture collection at the hospital and revised its evidence-based protocol. At the same time, Crouse began using Kurin®, a blood culture collection set with an automated specimen diversion device that diverts skin microbes. Allain reported significant reductions in contaminated blood culture rates and associated costs post intervention. Accounting for the cost of the Kurin device, Allain calculated that the hospital would save more than $185,000 per year.

Allain concluded the abstract acknowledging that even a hospital operating at the acceptable CBC benchmark rate, can further lower their CBC rate with this process improvement inclusive of education, compliance monitoring, and the use of Kurin blood collection device with automated specimen diversion.

In 2018, the National Association of Clinical Nurse Specialists (NACNS) received 267 abstracts for consideration. Every abstract underwent blind peer review by 3 reviewers and their scores were averaged. This abstract was among the highest scoring abstracts submitted to the conference.1

Download a PDF of this study.

1 Horner SD. Top Scoring Abstracts From the 2018 National Association of Clinical Nurse Specialists Annual Conference. Clinical Nurse Specialist. May/June 2018