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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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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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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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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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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