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Introduction ⬇

Blood cultures are collected whenever there is reason to suspect bacteremia or septicemia. Although mild transitory bacteremia is a frequent finding in many infections, a persistent, continuous, or recurrent bacteremia indicates a more serious condition that may require immediate treatment. The expeditious detection and identification of pathogens (bacteria, fungi, viruses, and parasites) in the blood may aid in making a clinical and etiologic diagnosis.

  1. Bacteremia

  2. Septicemia

  3. Shock

  4. Unexplained postoperative shock

  5. Postoperative shock after genitourinary tract manipulation or surgery

  6. Unexplained fever with a duration of several days

  7. Chills and fever in patients with:

    1. Infected burns

    2. Urinary tract infection (UTI)

    3. Rapidly progressing tissue infection

    4. Postoperative wound sepsis

    5. Indwelling venous or arterial catheter

  8. Debilitated patients receiving:

    1. Antibiotic drugs

    2. Corticosteroids

    3. Immunosuppressives

    4. Antimetabolites

    5. Parenteral hyperalimentation

  9. Following body piercing (nose, tongue, nipples, penis, umbilicus) with signs of infection and bacteremia

Procedure ⬆ ⬇

Procedure for Blood Culture

During venipuncture, because of the high potential for infecting the patient, aseptic technique must be used. Key points are listed as follows:

  1. Observe standard precautions. Perform hand hygiene and don gloves.

  2. Scrub the proposed puncture site with an antiseptic agent such as chlorhexidine. Allow to dry for 1–2 minutes.

  3. Cleanse the rubber stoppers of culture bottles with chlorhexidine and allow to air-dry.

  4. Perform venipuncture with a sterile syringe and needle; avoid contamination of the cleansed puncture site.

  5. Withdraw about 10–30 mL of blood into a 20-mL syringe or directly into the culture tubes. Because of the danger of accidental needle sticks, the practice of changing needles to transfer the specimen into blood culture bottles has been replaced by direct injection with the original phlebotomy needle.

  6. If two culture bottles are to be inoculated (one anaerobic and one aerobic), first inoculate the aerobic bottle with the optimal, manufacturer-recommended volume and then inoculate the anaerobic bottle with the remaining, being careful not to overinoculate. Be certain to inoculate each bottle with the optimum blood volume.

  7. Mix both bottles gently.

  8. Remove and discard gloves. Perform hand hygiene.

  9. Label specimens with the patient’s name, date, and tests ordered and immediately transfer them to the laboratory.

Procedural Alert

  1. Handle all blood specimens according to standard precautions.

  2. After disinfection, do not palpate the venipuncture site unless sterile gloves are worn. Palpation is the greatest potential cause of blood culture contamination.

  3. Specimens can be drawn from two or three different sites to exclude a skin-contaminating organism.

  4. Collection of more than three blood cultures in a 24-hour period does not improve the detection of bacteria.

  5. It is recommended to draw blood below an intravenous line (if possible) to prevent dilution of the sample.

Clinical Implications ⬆ ⬇

  1. Negative cultures: If all cultures, subcultures (if performed), and Gram-stained smears are negative, the blood culture may be reported as no growth after 5–7 days of incubation.

  2. Positive cultures: Pathogens most commonly found in blood cultures include:

    1. Bacteroides spp.

    2. Brucella spp.

    3. Enterobacteriaceae

    4. Pseudomonas aeruginosa

    5. Haemophilus influenzae

    6. Listeria monocytogenes

    7. Streptococcus pneumoniae

    8. Enterococcus spp.

    9. Staphylococcus aureus, Staphylococcus epidermidis

    10. Streptococcus spp. including beta-hemolytic streptococci

    11. Candida albicans

    12. Clostridium perfringens

Interventions ⬆ ⬇

Pretest Patient Care

  1. Explain purpose of and procedure for culture. Obtain and document pertinent history of signs and symptoms of infection.

  2. Follow guidelines in Chapter 1 for safe, effective, informed pretest care.

Posttest Patient Care

  1. Review test results; report and record findings. Modify the nursing care plan as needed. Monitor for bacteremia, septicemia, and other febrile illness. Counsel the patient appropriately about treatment (triple antibiotic therapy).

  2. Follow guidelines in Chapter 1 for safe, effective, informed posttest care.

Clinical Alert

The healthcare provider should be notified immediately about positive culture results so that treatment and isolation precautions are appropriate.

Interfering Factors ⬆ ⬇

Blood cultures are subject to contamination, especially by skin bacteria. These skin organisms should be identified if possible.

Reference Values ⬆

Normal

Negative for pathogens