Commentary: Blood Culture Contamination: A Clinical and Financial BurdenAuthor(s): Peter H. Gilligan, PhD, D(ABMM), F(AAM)Source: Infection Control and Hospital Epidemiology, Vol. 34, No. 1 (January 2013), pp. 22-23Published by: The University of Chicago Press on behalf of The Society for Healthcare Epidemiologyof AmericaStable URL: http://www.jstor.org/stable/10.1086/668771 .

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infection control and hospital epidemiology january 2013, vol. 34, no. 1

c o m m e n t a r y

Blood Culture Contamination: A Clinical and Financial Burden

Peter H. Gilligan, PhD, D(ABMM), F(AAM)1

(See the article by Washer et al, on pages 15–21.)

Affiliation: 1. Clinical Microbiology-Immunology Laboratories and Phlebotomy Services, University of North Carolina Hospitals, Chapel Hill, NorthCarolina; and University of North Carolina School of Medicine, Chapel Hill, North Carolina.

Received September 20, 2012; accepted September 20, 2012; electronically published November 26, 2012.� 2012 by The Society for Healthcare Epidemiology of America. All rights reserved. 0899-823X/2013/3401-0003$15.00. DOI: 10.1086/668771

The study by Washer et al1 in this issue of the journalreminds us of the clinical and financial burden that contam-inated blood cultures represent. Washer and colleagues ask afairly simple question: of the 3 antiseptics most widely usedto cleanse venipuncture sites prior to collection of blood forculture, which results in the lowest rate of contaminatedblood cultures? The answer that none is superior is consistentwith a recent Centers for Disease Control and Prevention(CDC) Laboratory Best Practices Guideline on practices thatreduce blood culture contamination.2 Besides the finding thatthe type of antiseptic used does not influence blood culturecontamination rates, 2 other practices are associated withreduced blood culture contamination rates: having blood cul-tures drawn by phlebotomists whose main duty is drawingblood and having blood drawn by venipuncture rather thanfrom intravenous catheters are strongly associated with re-duced rates of contamination.

The finding that the type of disinfectant used does notinfluence the contamination rate may be at odds with theresults of some previous studies,3,4 but the CDC’s systematicreview of the data suggests otherwise. One of the key strengthsof the study by Washer and colleagues is the use of a dedicatedphlebotomy team. It is likely that training a small group ofindividuals to properly apply antiseptics with different dwelltimes contributes to the impressively low contamination rateof less than 1% regardless of antiseptic used. This rate issuperior to that reported in many studies3-9 and is significantlybelow the American Society for Microbiology’s and Collegeof American Pathologists’ benchmark for contaminated bloodcultures, which is between 2.5% and 3%.4,10 Why are rateslower for phlebotomists than for other healthcare provid-ers?6,11,12 Simply put, it is because of training, practice, re-sources, and professionalism. At our institution, phleboto-mists routinely have a monthly blood culture contaminationrate of less than 1%, as was seen in the study of Washer andcolleagues. The training they receive includes one-on-one in-struction by a senior phlebotomist during their initial seriesof blood culture collection and retraining if their individual

contamination rates rise above 2%. This is not done with anyother healthcare provider in a systematic manner in our in-stitution. Phlebotomists draw the bulk of blood cultures ob-tained by venipuncture, so they are more practiced at thismethod. This is particularly key when drawing blood culturesfrom patients with poor venous access, who may require ve-nipuncture of hand or foot veins, something that trainedphlebotomists are comfortable doing, whereas many otherhealthcare providers are not. Phlebotomists also have all thesupplies at hand on individual carts that travel with them,unlike other professionals, who may have to scrounge aroundfor appropriate supplies. Finally, they take great pride in hav-ing contamination rates that are lower than those of any otherprofessional who draws blood cultures at our institution. Itis a benchmark of their worth to the institution, somethingof which they are well aware.

Why is reducing blood culture contamination rates im-portant? Simply put, contaminated blood cultures are ex-pensive and put patients at risk for significant iatrogenic com-plications. The seminal work by Bates et al13 was the first toquantify the cost of a contaminated blood culture, at $4,500.This cost was due to increased length of stay, typically of 1day; use of unnecessary antimicrobial therapy; and diagnostictesting. Subsequent studies have put this cost as high as$10,000.4,14 Let us use an illustration to understand the annualcost of contaminated blood cultures. Say that hospital A does20,000 blood cultures annually and has a 2.5% contaminationrate, while hospital B does 30,000 with a 1% contaminationrate. The cost of a contaminated blood culture at each in-stitution is $5,000. Hospital A, even though it does two-thirdsthe number of blood cultures, has an annual excess expensedue to contaminated blood cultures of $2,500,000, while hos-pital B has a cost of $1,500,000. In addition, hospital A has200 more hospital-days when a bed is not available comparedwith hospital B because of the increased length of stay of 1day. In hospitals that have a chronic shortage of beds, thoseextra 200 hospital bed–days would be highly useful.

The clinical impact of contaminated blood cultures is also

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burden of blood culture contamination 23

clear. Patients with contaminated blood cultures are just aslikely to receive antimicrobials as patients who have true bac-teremia,15 putting them at risk for complications associatedwith inappropriate antimicrobial treatment. These include al-teration of the microbiota; increased rates of colonizationwith multidrug-resistant organisms, including vancomycin-resistant enterococcus and methicillin-resistant Staphylococ-cus aureus; increased risk of Clostridium difficile infection; andallergic reactions to antimicrobials. Contaminated blood cul-tures complicate the interpretation of positive blood cultures.In some studies, as many as 50% of positive blood culturesare contaminants.4,13,15 The most prominent blood culturecontaminant is coagulase-negative staphylococci, which maybe responsible for as many as 75% of contaminated cul-tures.4,15 However, it may also be a true positive in approx-imately 10% of episodes in which it is recovered.15 Deter-mining whether it is a true positive or a contaminant maybe difficult, leading physicians to err on the side of cautionand overtreat patients with coagulase-negative staphylococci,especially those with indwelling central venous intravascularlines in place, the leading source of bacteremia and funge-mia.15

What strategies are proven to reduce contaminated bloodcultures? First, using any of the three antiseptics (properlyapplied) studied by Washer et al.1 Second, having a dedicatedphlebotomy team to collect blood cultures. Third, avoidingthe use of blood drawn for culture from intravascular linesor, if venous access is poor, having at least one culture col-lected by venipuncture at the time of the line draw. Fourth,avoiding the use of single blood cultures, if possible, becauseof the difficulty in interpreting the isolation of organismssuch as coagulase-negative staphylococci and viridians strep-tococci, which are common causes of blood culture contam-ination but at the same time may be clinically significant inthe appropriate clinical settings.4,13,15 And fifth, providingfeedback and education to those who collect contaminatedblood cultures at a rate above a specific benchmark5,7,12 toimprove this process in the future.

acknowledgments

Potential conflicts of interest. All authors report no conflicts of interest rel-evant to this article. All authors submitted the ICMJE Form for Disclosureof Potential Conflicts of Interest, and the conflicts that the editors considerrelevant to this article are disclosed here.

Address correspondence to Peter H. Gilligan, PhD, D(ABMM), F(AAM),Clinical Microbiology-Immunology Laboratories, CB 7600, UNC Hospitals,Chapel Hill, NC 27514 (pgilliga@unch.unc.edu).

references

1. Washer LL, Chenoweth C, Kim H-W, et al. Blood culture con-tamination: a randomized trial evaluating the comparative ef-fectiveness of 3 skin antiseptic interventions. Infect Control HospEpidemiol 2013;34(1):15–21(in this issue).

2. Snyder SR, Favoretto AM, Baetz RA, et al. Effectiveness of prac-tices to reduce blood culture contamination: a Laboratory Med-icine Best Practices systematic review and meta-analysis. ClinBiochem 2012;45(13–14):999–1011.

3. Suwanpimolkul G, Pongkumpai M, Suankratay C. A random-ized trial of 2% chlorhexidine tincture compared with 10%aqueous povidone-iodine for venipuncture site disinfection: ef-fects on blood culture contamination rates. J Infect 2008;56(5):354–359.

4. Hall KK, Lyman JA. Updated review of blood culture contam-ination. Clin Microbiol Rev 2006;19(4):788–802.

5. Youssef D, Shams W, Bailey B, et al. Effective strategy for de-creasing blood culture contamination rates: the experience of aVeterans Affairs medical centre. J Hosp Infect 2012;81(4):288–291.

6. Gander RM, Byrd L, DeCrescenzo M, et al. Impact of bloodcultures drawn by phlebotomy on contamination rates andhealth care costs in a hospital emergency department. J ClinMicrobiol 2009;47(4):1021–1024.

7. Roth A, Wiklund AE, Palsson AS, et al. Reducing blood culturecontamination by a simple informational intervention. J ClinMicrobiol 2010;48(12):4552–4558.

8. Archibald LK, Pallangyo K, Kazembe P, et al. Blood culturecontamination in Tanzania, Malawi, and the United States: amicrobiological tale of three cities. J Clin Microbiol 2006;44(12):4425–4429.

9. Calfee DP, Farr BM. Comparison of four antiseptic preparationsfor skin in the prevention of contamination of percutaneouslydrawn blood cultures: a randomized trial. J Clin Microbiol 2002;40(5):1660–1665.

10. Bekeris LG, Tworek JA, Walsh MK, et al. Trends in blood culturecontamination: a College of American Pathologists Q-Tracksstudy of 356 institutions. Arch Pathol Lab Med 2005;129(10):1222–1225.

11. Norberg A, Christopher NC, Ramundo ML, et al. Contami-nation rates of blood cultures obtained by dedicated phlebotomyvs intravenous catheter. JAMA 2003;289(6):726–729.

12. Weinbaum FI, Lavie S, Danek M, Sixsmith D, Heinrich GF, MillsSS. Doing it right the first time: quality improvement and thecontaminant blood culture. J Clin Microbiol 1997;35(3):563–565.

13. Bates DW, Goldman L, Lee TH. Contaminant blood culturesand resource utilization: the true consequences of false-positiveresults. JAMA 1991;265(3):365–369.

14. Alahmadi YM, Aldeyab MA, McElnay JC, et al. Clinical andeconomic impact of contaminated blood cultures within thehospital setting. J Hosp Infect 2011;77(3):233–236.

15. Pien BC, Sundaram P, Raoof N, et al. The clinical and prognosticimportance of positive blood cultures in adults. Am J Med 2010;123(9):819–828.

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