Official reprint from UpToDate®
www.uptodate.com ©2016 UpToDate®

Blood cultures for the detection of bacteremia

Gary V Doern, MD
Section Editor
Stephen B Calderwood, MD
Deputy Editor
Elinor L Baron, MD, DTMH


Blood is one of the most important specimens received by the microbiology laboratory for culture, and culture of blood is usually the most sensitive method for detection of bacteremia or fungemia. Issues related to types of bacteremia, indications, and technique for blood cultures will be reviewed here. Issues related to specimen transport and Gram stain interpretation are discussed in detail separately. (See "Microbiology specimen collection and transport" and "Approach to Gram stain and culture results in the microbiology laboratory".)


Blood cultures should be obtained (prior to initiation of antimicrobial therapy) for any patient in whom there is suspicion of bacteremia or fungemia, including hospitalized patients and selected outpatients with fever and leukocytosis or leukopenia [1]. However, a normal white blood cell count does not rule out bacteremia [2,3]. Circumstances in which blood cultures are especially important include known or suspected sepsis, meningitis, osteomyelitis, arthritis, endocarditis, peritonitis, pneumonia, and fever of unknown origin.

Indications for follow-up blood cultures are discussed below. (See 'Follow-up blood cultures' below.)


In general, adult patients with bacteremia are likely to have low quantities of bacteria in the blood, even in the setting of sepsis. In addition, bacteremia in adults is generally intermittent. For this reason, multiple blood cultures, each containing large volumes of blood, are required to detect bacteremia. Prior to initiation of antimicrobial therapy, at least two sets of blood cultures taken from separate venipuncture sites should be obtained [4]. The technique, number of cultures, and volume of blood are more important factors for detection of bacteremia than timing of culture collection; these are discussed further in the following sections.

Technique — Careful technique is critical to avoid contamination of the blood culture media by normal skin flora during the process of collection. This is important because normal bacterial skin flora can also cause systemic disease, such as infective endocarditis, and in some circumstances blood culture contamination can make it difficult to distinguish between false-positive results and true infection. Measures to reduce contamination include effective disinfection of the venipuncture site and avoiding blood culture collection through existing intravenous lines [5-9].


Subscribers log in here

To continue reading this article, you must log in with your personal, hospital, or group practice subscription. For more information or to purchase a personal subscription, click below on the option that best describes you:
Literature review current through: Sep 2016. | This topic last updated: Sep 13, 2016.
The content on the UpToDate website is not intended nor recommended as a substitute for medical advice, diagnosis, or treatment. Always seek the advice of your own physician or other qualified health care professional regarding any medical questions or conditions. The use of this website is governed by the UpToDate Terms of Use ©2016 UpToDate, Inc.
  1. Coburn B, Morris AM, Tomlinson G, Detsky AS. Does this adult patient with suspected bacteremia require blood cultures? JAMA 2012; 308:502.
  2. Seigel TA, Cocchi MN, Salciccioli J, et al. Inadequacy of temperature and white blood cell count in predicting bacteremia in patients with suspected infection. J Emerg Med 2012; 42:254.
  3. Fu CM, Tseng WP, Chiang WC, et al. Occult Staphylococcus aureus bacteremia in adult emergency department patients: rare but important. Clin Infect Dis 2012; 54:1536.
  4. Weinstein MP. Current blood culture methods and systems: clinical concepts, technology, and interpretation of results. Clin Infect Dis 1996; 23:40.
  5. Little JR, Murray PR, Traynor PS, Spitznagel E. A randomized trial of povidone-iodine compared with iodine tincture for venipuncture site disinfection: effects on rates of blood culture contamination. Am J Med 1999; 107:119.
  6. Strand CL, Wajsbort RR, Sturmann K. Effect of iodophor vs iodine tincture skin preparation on blood culture contamination rate. JAMA 1993; 269:1004.
  7. Mimoz O, Karim A, Mercat A, et al. Chlorhexidine compared with povidone-iodine as skin preparation before blood culture. A randomized, controlled trial. Ann Intern Med 1999; 131:834.
  8. Schifman RB, Pindur A. The effect of skin disinfection materials on reducing blood culture contamination. Am J Clin Pathol 1993; 99:536.
  9. Tafuro P, Colbourn D, Gurevich I, et al. Comparison of blood cultures obtained simultaneously by venepuncture and from vascular lines. J Hosp Infect 1986; 7:283.
  10. Tamma PD, Aucott SW, Milstone AM. Chlorhexidine use in the neonatal intensive care unit: results from a national survey. Infect Control Hosp Epidemiol 2010; 31:846.
  11. Chapman AK, Aucott SW, Milstone AM. Safety of chlorhexidine gluconate used for skin antisepsis in the preterm infant. J Perinatol 2012; 32:4.
  12. Archibald LK, Pallangyo K, Kazembe P, Reller LB. Blood culture contamination in Tanzania, Malawi, and the United States: a microbiological tale of three cities. J Clin Microbiol 2006; 44:4425.
  13. Norberg A, Christopher NC, Ramundo ML, et al. Contamination rates of blood cultures obtained by dedicated phlebotomy vs intravenous catheter. JAMA 2003; 289:726.
  14. Boyce JM, Nadeau J, Dumigan D, et al. Obtaining blood cultures by venipuncture versus from central lines: impact on blood culture contamination rates and potential effect on central line-associated bloodstream infection reporting. Infect Control Hosp Epidemiol 2013; 34:1042.
  15. Lee A, Mirrett S, Reller LB, Weinstein MP. Detection of bloodstream infections in adults: how many blood cultures are needed? J Clin Microbiol 2007; 45:3546.
  16. Patel R, Vetter EA, Harmsen WS, et al. Optimized pathogen detection with 30- compared to 20-milliliter blood culture draws. J Clin Microbiol 2011; 49:4047.
  17. Cockerill FR 3rd, Wilson JW, Vetter EA, et al. Optimal testing parameters for blood cultures. Clin Infect Dis 2004; 38:1724.
  18. Mirrett S, Weinstein MP, Reimer LG, et al. Relevance of the number of positive bottles in determining clinical significance of coagulase-negative staphylococci in blood cultures. J Clin Microbiol 2001; 39:3279.
  19. Connell TG, Rele M, Cowley D, et al. How reliable is a negative blood culture result? Volume of blood submitted for culture in routine practice in a children's hospital. Pediatrics 2007; 119:891.
  20. Schelonka RL, Chai MK, Yoder BA, et al. Volume of blood required to detect common neonatal pathogens. J Pediatr 1996; 129:275.
  21. Isaacman DJ, Karasic RB, Reynolds EA, Kost SI. Effect of number of blood cultures and volume of blood on detection of bacteremia in children. J Pediatr 1996; 128:190.
  22. Brown DR, Kutler D, Rai B, et al. Bacterial concentration and blood volume required for a positive blood culture. J Perinatol 1995; 15:157.
  23. Kaditis AG, O'Marcaigh AS, Rhodes KH, et al. Yield of positive blood cultures in pediatric oncology patients by a new method of blood culture collection. Pediatr Infect Dis J 1996; 15:615.
  24. Baron EJ, Miller JM, Weinstein MP, et al. A guide to utilization of the microbiology laboratory for diagnosis of infectious diseases: 2013 recommendations by the Infectious Diseases Society of America (IDSA) and the American Society for Microbiology (ASM)(a). Clin Infect Dis 2013; 57:e22.
  25. Ilstrup DM, Washington JA 2nd. The importance of volume of blood cultured in the detection of bacteremia and fungemia. Diagn Microbiol Infect Dis 1983; 1:107.
  26. Mermel LA, Maki DG. Detection of bacteremia in adults: consequences of culturing an inadequate volume of blood. Ann Intern Med 1993; 119:270.
  27. Riedel S, Bourbeau P, Swartz B, et al. Timing of specimen collection for blood cultures from febrile patients with bacteremia. J Clin Microbiol 2008; 46:1381.
  28. Doern GV, Brueggemann AB, Dunne WM, et al. Four-day incubation period for blood culture bottles processed with the Difco ESP blood culture system. J Clin Microbiol 1997; 35:1290.
  29. Petti CA, Bhally HS, Weinstein MP, et al. Utility of extended blood culture incubation for isolation of Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, and Kingella organisms: a retrospective multicenter evaluation. J Clin Microbiol 2006; 44:257.
  30. Baron EJ, Scott JD, Tompkins LS. Prolonged incubation and extensive subculturing do not increase recovery of clinically significant microorganisms from standard automated blood cultures. Clin Infect Dis 2005; 41:1677.
  31. Karen C. Carroll, Melvin P. Weinstein. Manual and Automated Systems for Detection and Identification of Microorganisms. In: Manual of Clinical Microbiology, 9th, Patrick R. Murray. (Ed), ASM Press, Washington, D.C. 2007. p.192.
  32. Banerjee R, Teng CB, Cunningham SA, et al. Randomized Trial of Rapid Multiplex Polymerase Chain Reaction-Based Blood Culture Identification and Susceptibility Testing. Clin Infect Dis 2015; 61:1071.
  33. Vincent JL, Brealey D, Libert N, et al. Rapid Diagnosis of Infection in the Critically Ill, a Multicenter Study of Molecular Detection in Bloodstream Infections, Pneumonia, and Sterile Site Infections. Crit Care Med 2015; 43:2283.
  34. Richter SS, Beekmann SE, Croco JL, et al. Minimizing the workup of blood culture contaminants: implementation and evaluation of a laboratory-based algorithm. J Clin Microbiol 2002; 40:2437.
  35. Pien BC, Sundaram P, Raoof N, et al. The clinical and prognostic importance of positive blood cultures in adults. Am J Med 2010; 123:819.