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The phlebotomist's role in the collection phase of a blood culture.

The person who must train phlebotomists sometimes faces difficulty in conveying the importance of the phlebotomist's role in the collection of a blood culture. Many new employees are in the healthcare setting for the first time, or they have had little or no microbiology exposure. The following article discusses how to collect a quality blood culture sample and why certain procedures are vital.

The phlebotomist's role in the collection phase of a blood culture is critical to a quality specimen and the release of pertinent results by the bacteriology department.

At our institution, a dedicated team of phlebotomists collects blood specimens for several clinical laboratories. For the educator and trainer of the phlebotomists, conveying the importance of the phlebotomist's role is sometimes difficult. Many of the new employees I train in phlebotomy are new to the healthcare setting. Others have had limited exposure either in high schools or post-secondary classes, or no exposure at all. Terms such as "skin flora," "pathogenic," "antiseptic," "sterile," "disinfectant," "bacteremia," "septicemia," "contamination," and "false positive blood cultures" are a foreign vocabulary.

My dilemma is how to impress on the new phlebotomists the impact they have on the quality of the results the laboratory releases. The phlebotomist's goal is to collect a quality specimen by the safest means possible -- for both the patient and the phlebotomist.

We preface any discussion of procedures with the importance of patient identification, as well as safety. Without correct patient identification, the collected specimens have no value and could lead to serious consequences for the patients involved. As an instructor, I believe it is important for phlebotomists to know not only "how" to collect a quality blood culture sample, but the "why" of what they do. The phlebotomy students might know the definitions of the above terms, but could they really apply these terms to their work?

Before we began our discussion of the collection process for blood cultures, the class examined background material and definitions. We defined "bacteremia" as the presence of microorganisms in the blood and "septicemia" as the systemic disease associated with the presence of pathogenic microorganisms, or their toxins, in the blood.

We defined "skin flora" as the naturally occurring bacteria found on the human skin. Microorganisms capable of causing a disease under the right circumstances are then defined as "pathogenic."

The terms "aseptic" and "sterile" were also explored. Could we "sterilize" the skin in preparation for a blood culture collection, or did we achieve "aseptic" conditions? "Aseptic" was defined as free of microorganisms capable of causing infection or contamination. "Sterile" was defined as free of all living organisms. Inanimate objects (instruments, equipment, etc.) can be sterilized or disinfected, but the best we can do with human skin is to create an aseptic field.

The final terms discussed were "blood culture," "true positive blood culture," and "false positive culture." A "blood culture" was defined as an aseptically collected blood sample from a single venipuncture inoculated to media that will support microbial growth. A "positive blood culture" was defined as a blood culture in which an organism's presence at the time of collection is supported by convincing clinical evidence. A "false positive culture" was defined as a blood culture that did not have clinical evidence to support the organism's presence, and possible evidence suggesting the organism did not come from the patient's blood.

After terms were defined, we looked at the common sources of bacteremia. I asked the students to identify the most common culture they transported to the clinical laboratory. Their answer was a urine specimen for culture and susceptibilities. This supported the statistics that 25% of bacteremia sources are from the genitourinary tract system (Washington (1982), Hindler (1997)). The respiratory tract, abscesses, surgical wounds, other known sites, and the biliary tract account for approximately 50% of bacteremia sources (Washington (1982), Hindler (1997)). The remaining sources of 25% of bacteremia are unknown. (Washington (1982), Hindler (1997)) I asked the phlebotomists to consider whether our collection process/technique could contribute to the remaining 25%.

The next issue examined by the class was why blood cultures are collected, and what are some critical factors that determine the collections. The students and I looked at four factors: number of cultures to be collected, the volume to be collected, timing of cultures, and site preparation.

Number of cultures

From studies done at our institution several years back on more than 5,000 cultures, and more recent studies in the literature, the recovery rate with the collection of one blood culture was determined to be approximately 80% (Washington (1975), Mermel (1993)). When a second culture is collected, the recovery rate goes up to 90% (Washington (1975), Mermel (1993)). With a third collection, the recovery rate goes up to 99% (Washington (1975), Mermel (1993)). After these statistics were presented, the students asked, why not keep collecting more blood to reach 100% recovery in a 24-hour time frame? It was explained that we would never be assured of 100% possibility of recovery. With this, the students learned a new term: "iatrogenic anemia." Iatrogenic anemia occurs when too much blood has been collected from a patient, causing additional medical problems.

Volume of blood collected

The second factor discussed was the volume of blood to be collected per culture. The volume collected is of primary importance for recovery of microorganisms from the blood. Taking into account iatrogenic effects and the recommendations from the literature, 10mL is considered the lower limit and 20-30mL as the optimal amount for recovery sensitivity on the adult patient (Ilstrup (1983), Washington (1991)). Collecting more than 30mL per culture provides no added value and could subject the patient to iatrogenic problems.

Timing of cultures

The third factor discussed was the timing for collection of the blood cultures, because the new phlebotomy student usually wants a definite time interval to remember. This resulted in a discussion of the clinical patterns of bacteremia -- transient, intermittent, and continuous.

In the healthy population, when there is a sudden influx of bacteria into the blood due to manipulation of infected tissue (due to dental work, catheters, phlebotomy, etc.) this bacteria is cleared out of the blood, within a time frame ranging from a few minutes up to hours, by the liver and spleen. This was an example of a "transient bacteremia."

An "intermittent bacteremia" is commonly known as "fever of undetermined origin." Intermittent bacteremia can involve a wide variety of abscesses, which shed bacteria into the blood at irregular times.

The third pattern is the "continuous bacteremia," in which the body sheds bacteria directly into the blood stream (example: intravascular foci of infection, acute or subacute bacterial endocarditis). After the discussion of the three clinical patterns, the students had a better understanding of why it is the physician who specifies at what intervals we are to collect the cultures.

The next question was: If nothing is written on the patient's order forms, when do we collect the second culture? In that case, in our institution, the phlebotomist will go back to collect the second culture within 30-60 minutes.

Site preparation

The final factor discussed with the phlebotomy students was site preparation or skin antisepsis, and the importance of our established standard operating procedure for blood culture collections. I explained to the phlebotomy students that the clinical bacteriology laboratory's goal is to keep the percent of false positive cultures very low because of both cost and workload issues. Bates (1991), Weinbaum (1997), Gibbs (1997), and Schifman (1998) have done studies on the issues of contaminated blood culture collections. The study done by Bates and Weinbaum illustrated that with a false positive blood culture, the cost to the patient could be an additional $4,000-5,000. This cost included the additional days of stay in the hospital, additional pharmacy charges, and additional laboratory charges.

I devised the concept of our study while conducting a lecture/lab on blood cultures collection. At the end of the lecture, I posed two questions: How can we best serve the patient when collecting blood culture specimens? Will deviation from the standard procedure affect the phlebotomist's service to the patient? The students in turn posed their own question to me: "What is 'normal flora' and/or skin flora and how does that relate to the cleansing procedure for blood culture collections?"

As adult learners, we understand and retain concepts if we can visualize a concept rather than try to memorize a term or idea. I wanted to find a means to illustrate normal flora and the impact on the blood culture collection. To help understand the concept of normal flora, I devised a study with the help of my phlebotomy students and staff. We named our study "A Picture is Worth 1,000 Words."

At the time of the study, povidone iodine was the disinfectant being used for cleansing sites for blood culture collection at our institution. Because we were conducting evaluations on tincture of iodine as a possible substitute for povidone iodine, we decided to use both solutions to see which was most effective.

The study

The experiment was set up to culture skin prior to disinfection to illustrate the presence of normal flora on the skin. Another culture of the skin was done after the antiseptic scrub to illustrate that organisms capable of contaminating blood cultures were no longer present. A third skin prep involved a "sloppy" or "quick scrub," which was not done according to the established procedures.

The three collections were done in duplicate using povidone-iodine and tincture of iodine preparation. Becton Dickinson Rodac [TM] plates were used because their raised surface is ideal for such activity.

A plate was inoculated before and after skin cleaning for each method and solution, using the established protocol for each. The plates were incubated for 24 hours at the appropriate temperature. Three sets of agar plates were used: the first and third sets were inoculated from the arms of phlebotomists and phlebotomy students working in an outpatient setting. The second set of agar plates was inoculated from a hospitalized patient.

Before the collection site was cleansed, a sterile Rodac plate was touched to the site. The site was then cleansed with a povidone-iodine following our established procedure. Immediately before performing the venipuncture procedure, a second sterile Roclac plate was touched to the prepared site. The same procedure was repeated on another phlebotomist using a tincture of iodine preparation.

The second set of plates was used in an inpatient setting. With the patient's permission, plates were inoculated before and after skin cleansing according to the same protocol, utilizing both povidone-iodine and tincture of iodine solutions.

The phlebotomists has not seen the results of the 24-hour incubation and remained skeptical of the outcome of our study. One student asked the question: "Is the length of time specified in the procedures really that critical?" Was the time of two minutes for povidone-iodine and one-minute contact time for tincture of iodine important? If a "quick" scrub were done, would some of the normal flora still be present on the skin? A third set of plates was inoculated from a student's arm in the phlebotomy classroom to demonstrate a "sloppy" or "quick" scrub.

What was learned?

We all have normal flora growing on our skin. The students were amazed at what was cultured from a normal individual's skin.

The hospital patient's skin culture provided three lessons:

* We can't always tell by visual inspection if a surface is contaminated with pathogenic organisms.

* The culture plates demonstrated the importance of NCCLS guidelines on washing hands after every patient before going on to the next patient.

* Established antiseptic contact time in the procedure is essential.

A pure culture of Staphylococcus aureus was isolated from the hospitalized patient's arm. The comment was made that the arm of this patient looked "normal." The students observed that if the phlebotomist had touched the arm before donning gloves and didn't wash after the gloves were removed, and then had gone on to the next patient without washing hands, the phlebotomist could have transmitted a nosocomial infection.

The third lesson learned was the effect a "sloppy scrub" has on blood cultures. The Rodac plate was touched to the skin to include an area where iodine was in contact with the skin for less than the acceptable minimum time for effective site preparation. The students could see that organisms remained capable of contaminating a blood culture.

By following the established skin cleansing procedures for the collection of a blood culture, proper skin antisepsis is obtained. The phiebotomist must make the intended puncture site free of microorganisms capable of causing contamination. The plates inoculated before cleansing in the three sets showed growth of normal flora in two out of three sets. The plates inoculated after cleansing with either antiseptic showed no growth of bacteria.

The plates inoculated after a "quick" scrub showed growth of normal flora, but the growth was inhibited. However, the inhibited organisms could still cause a false positive culture.

Providone iodine and tincture of iodine gave comparable results, provided the established collection procedure for each was adhered to.


A similar study using blood agar plates and sterile swabs was recently conducted with the Phlebotomy Technician students at Rochester Community and Technical College (RCTC). In this study, a sterile swab (moistened with sterile water) was rolled across the site and used to inoculate the blood agar plate. The same procedure was conducted after the skin was prepared with tincture of iodine for the blood culture following established protocol on a second blood agar plate. The results were similar to ours. The same principles of proper site preparation were easily demonstrated.


The study turned out to be a learning tool for the students and our staff phlebotomist. A poster of the study and accompanying photos from the study were displayed at our annual skills fair for Laboratory Services (Phle botomy) that is held each January. The study has been easily replicated using blood agar plates. The blood agar plates will be less costly and easier to obtain than the environmental culture media. With the cooperation of the bacteriology laboratory, this is a relatively simple study to conduct with the potential of being an excellent teaching tool for students and staff.


All the plate pictures were taken of 24-hour-old cultures with the exception of the "quick" scrub plates. These were photographed using 72-hour-old culture plates.

Ruth Jacobsen is Vascular Access Education Coordinator -- Laboratory Services (Phlebotomy) and Phlebotomy Technician Program Director at the Mayo School of Health Sciences in Rochester, MN. The studies described were done in cooperation with Hiltor Desk C phlebotomy staff, Charlton phlebotomy staff, and Mayo phlebotomy students at Mayo Clinic, as well as students in the Phlebotomy Technician Program at Rochester Community & Technical College in Rochester, MN. The original study was conducted December 1997-January 1998, and follow-up studies were conducted spring and fall semesters, 2000, and spring (March), 2001.

Suggested Readings

Bates, D. W., Goldman, L., & Lee, T. H. (1991). Contaminant Blood Cultures and Resource Utilization: The True Consequences. JAMA. 265(3), 365-369.

Becton Dickinson Rodac package insert (88-0894-1) Revised: January 1999.

Garza, D. & Becan-McBride, K. (1996). Phlebotomy Handbook (4th ed.). Stamford, Connecticut: Appleton & Lange.

Gibb, A. P., Hill, B., Chorel, B., & Brant, R. (1997). Reduction in Blood Culture Contamination Rate by Feedback to Phlebotomists. Arch. Pathol. Lab Med. 121. 503-507.

Hindler, J. (Coordinating Ed.). (1997). Blood Culture III, Cumitech IB, American Society for Microbiology.

Ilstrup, D. M. & Washington II, J. A.(1983). The Importance of Volume of Blood Cultured in the Detection of Bacteremia and Fungemia. Diagn Microbiol Infect Dis. 1. 107-110.

Isenberg, H. D. (Ed.). (1998). Essential Procedures for Clinical Microbiology. Washington D.C.: ASM Press. 58-62.

McCall, R. E. & Tankersley, C. M. (1998). Phlebotomy Essentials (2nd ed.). Philadelphia: Lippincotte.

Mermel, L. A. & Maki, D. G. (1993). Detection of Bacteremia in Adults: Consequences of Culturing an Inadequate Volume of Blood. Annals of Internal Medicine. 119(4). 270-272.

Procedure for the Collection of Diagnostic Blood Specimens by Venipuncture, 4th ed. (1998). H3-A4. NCCLS. 18(7).

Protection of Laboratory Workers from Instrument Biohazards and Infectious Disease Transmitted by Blood, Body Fluids, and Tissue. (1997).NCCLS M29

Ringel, M. (1995). For Reliable Culture Results, Take Multiple Specimens. CAP Today.

Schifman, R.B. & Pindur, A. (1993). The effect of Skin Disinfection Materials on Reducing Blood Culture Contamination. American Journal of Clinical Pathology. 99(5). 536-538.

Schifman, R.B., Strand, C. L. (1993) Blood Culture Contamination Data Analysis and Critique. College of American Pathologists: Q-Probes.

Schifman, R.B., Strand, C. L., Meier, F. A. & Howanitz, P. J. (1998). Blood Culture Contamination. Arch Pathol Lab Med. 122. 216-221.

Strand, C. L., Wajsbort, R. R., & Sturman, K. (1993). Effects of Iodophor vs Iodine Tincture Skin Preparation on Blood Culture Contamination Rates. JAMA. 269(8). 1004-1006.

Washington, J. A. II (1975.). Blood Culture: Principles & Techniques. Mayo Clinic Proceedings. 50. 91-95.

Washington, J. A. II (1994). Collection, Transport, & Processing of Blood Cultures. Clinics in Laboratory Medicine. 14(1). 59-68.

Washington, J. A. II(1991). Issues in the Laboratory Diagnosis of Septicemia. Lab Notes: A Newsletter From Becton Dickinson Vacutainer Systems. 2(2).

Washington, J. A. II( Editor). (1985). Laboratory Procedures in Clinical Microbiology. New York: Springer-Verlag.

Washington, J. A. II(Coordinating Editor). (1982). Blood Culture II. Cumitech 1A, American Society for Microbiology.

Weinbaum, F. I., Lavie, S., Danek, M., Sixsmith, D., Heinrich, G. F., & Mills, S. S. (1997). Doing it right the First Time: Quality Improvement and the Contaminant Blood Culture. Journal of Clinical Microbiology. 35(3). 563-565.
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Author:Jacobsen, Ruth
Publication:Medical Laboratory Observer
Article Type:Brief Article
Geographic Code:1USA
Date:Aug 1, 2001
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