A Comprehensive Update on the Problem of Blood Culture Contamination and a Discussion of Methods for Addressing the Problem

Doern GV, Carroll KC, Diekema DJ, Garey KW, Rupp ME, Weinstein MP, Sexton DJ.
Clin Microbiol Rev. 2019 Oct 30;33(1).
University of Iowa Carver College of Medicine, Iowa City, Iowa.

  • Multiple studies show an increased use of unnecessary antibiotics with Blood Culture Contamination (BCCs) (34-41% of patients) for approximately ~7 days after the contamination.
  • BCCs result in delays in obtaining the correct diagnosis and initiating appropriate therapy.
  • All six of the cohort studies evaluated demonstrate consistently increased hospital costs or charges associated with blood culture contamination.
  • The authors conclude, “It is our opinion, however, that overall institutional rates of <1% are now achievable, and therefore, consideration should be given to the establishment of a new universal threshold value of <1%.”

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Antibiotic Resistance Threats in United States 2019

The Centers for Disease Control and Prevention

  • More than 2.8M antibiotic resistant infections occur in the US each year, and more than 35,000 people die as a result. This means, on average, someone gets an antibiotic resistant infection every 11 seconds and someone dies of this infection every 15 minutes.
  • One of the three important measures cited is: Slowing the development of resistance through improved antibiotic use.
  • C. diff is related to antibiotic use and antibiotic resistance, and contributes 224,000 cases and 12,800 deaths each year.

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Assessment of Cost, Morbidity, and Mortality Associated with Blood Culture Contamination

Davis KA, Painter J, Lakkad M, Dare RK
Open Forum Infectious Diseases, 6 (2): S676. October 2019.

  • This is the largest known study evaluating the clinical and financial impact of blood culture contamination (BCC) with inclusion of 1,102 cases and 11,266 controls during a 5-year period.
  • The study is the first reporting increased mortality associated with BCC. It also shows a correlation with increased length of stay (2 days), unnecessary exposure to antibiotics (1.3 days of treatment) and procedures, development of antibiotic-associated adverse events, and higher hospital charges.
  • Clinical outcome measures were significantly higher in patients with false positive test results.
    • Clinical Measure
    • Vancomycin ordered
    • ID consult
    • In-hospital mortality
    • Hospital charges
    • With false positives results
    • 81.3%
    • 16%
    • 8%
    • $36,008
    • With negative results
    • 64.9%
    • 12.9%
    • 4.6%
    • $28,875
  • The authors concluded that the implementation of innovative strategies to reduce contamination should be pursued. Antimicrobial stewardship programs should prioritize identification of contaminants and rapid de-escalation of inappropriate antibiotics to improve patient care.

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Multidisciplinary team review of best practices for collection and handling of blood cultures to determine effective interventions for increasing the yield of true-positive bacteremia, reducing contamination, and eliminating false-positive central line-associated bloodstream infections

Garcia RA, Spitzer ED, Beaudry J, Beck C, Diblasi R, Gilleeny-Blabac M, Haugaard C, Heuschneider S, Kranz BP, McLean K, Morales KL, Owens S, Paciella ME, Torregrosa E
Am J Infect Control. 2015 Nov 1;43(11):1222-37.
Stony Brook University Hospital, Stony Brook, NY

  • Skin, however, cannot be sterilized during antisepsis procedures because approximately 20% of bacteria are imbedded within deep layers of the epidermis and dermis.
  • Blood cultures should be obtained prior to starting antibiotic therapy to optimize the recovery of pathogens.
  • Estimated up to 50% of all blood cultures originate in the ED. Crowding in EDs is correlated with higher rates.
  • Improper collection of blood cultures is associated with suboptimal treatment of patients, increased financial burdens, and potential over-reporting of CLABSI.
  • Costs of a false positive blood culture range from $4500-$10,000.

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Impact of blood cultures drawn by phlebotomy on contamination rates and health care costs in a hospital emergency department

Gander RM, Byrd L, DeCrescenzo M, Hirany S, Bowen M, Baughman J
J Clin Microbiol. 2009 Apr;47(4):1021-4.
University of Texas Southwestern Medical Center, Dallas, Texas

  • Demonstrated the value of phlebotomists in reducing rates of false positive blood cultures.
  • Phlebotomists had a false positive blood cultures rate of 3.1 which was better than the non-phlebotomists (5.6 and 7.4).
  • Comparison of median patient charges between negative and false-positive episodes ($18,752 versus $27,472) showed a $8,720 difference while the median length of stay increased from 4 to 5 days.
  • By utilizing phlebotomists to collect blood cultures in the ED, contamination rates were lowered to recommended levels, with projected reductions in patient charges of approximately $4.1 million per year

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A national survey of interventions and practices in the prevention of blood culture contamination and associated adverse health care events

Garcia RA, Spitzer ED, Kranz B, Barnes S
Am J Infect Control. 2018 May;46(5):571-576. Epub 2017 Feb 1.
Stony Brook University Hospital, Stony Brook, NY

  • 80% of respondents report a blood culture contamination rate less than 3%.
  • 90% of hospital protocols emphasize direct venipuncture.
  • About 60% report that hospitals likely submit CLABSI data to NHSN attributable to blood culture contamination.

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Blood culture use in the emergency department in patients hospitalized for community-acquired pneumonia

Makam AN, Auerbach AD, Steinman MA.
JAMA Intern Med. 2014 May;174(5):803-6.
University of Texas Southwestern Medical Center, Dallas, Texas

  • The proportion of cultures collected in the ED during these visits increased from 10% in 2002 to 20% in 2010.
  • The proportion of cultures collected in patients hospitalized with community-acquired pneumonia (CAP) increased from 29% in 2002 to 51% in 2010, a 76% relative increase.
  • One potential explanation for increasing culture rates is that the JCAHO/CMS core measure (PN-3b) announced in 2002 mandated that if a culture is collected in the ED, it should be collected prior to antibiotic administration. This encouraged providers to reflexively order cultures in all patients admitted with CAP for whom antibiotic administration is anticipated.

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Updated Review of Blood Culture Contamination

Hall and Lyman
Clin Microbiol Rev. 2006 Oct; 19(4): 788–802.
University of Virginia School of Medicine, Charlottesville, Virginia

  • Rates vary widely from 0.6% to over 6%.
  • Rates have been on the increase.
  • Not everyone follows the recommendation of having two samples.
  • Positive predictive value goes up if two of two blood cultures were positive and both taken from the vein.
  • Skin antisepsis cannot entirely prevent the contamination of blood cultures

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Analysis of strategies to improve cost effectiveness of blood cultures

Zwang O, Albert RK.
J Hosp Med. 2006 Sep;1(5):272-6.
Denver Health Med Center, Denver CO

  • Positive predictive value of a positive blood culture was only 53%.
  • A 50% reduction in false positives would save approximately twice as much as a 50% reduction in false negatives.
  • Although only 6% of the blood cultures represented contaminants, their associated cost was more than twice that associated with the 87% that were true negatives.

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Reducing blood culture contamination in the emergency department: an interrupted time series quality improvement study

Self WH, Speroff T, Grijalva CG, McNaughton CD, Ashburn J, Liu D, Arbogast PG, Russ S, Storrow AB, Talbot TR.
Acad Emerg Med. 2013 Jan;20(1):89-97.
Vanderbilt University School of Medicine, Nashville, TN

  • The study objective was to develop and evaluate the effectiveness of a quality improvement (QI) intervention for reducing blood culture contamination in an ED.
  • The QI intervention involved changing the technique of blood culture specimen collection from the traditional clean procedure, to a new sterile procedure, with standardized use of sterile gloves and a new materials kit containing a 2% CHG skin antisepsis device, a sterile fenestrated drape, a sterile needle, and a procedural checklist.
  • During the baseline period, (4.3%) cultures were contaminated, compared to (1.7%) during the intervention period.

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