Blood Culture Collection Guidelines

  1. INDICATIONS
    1. Blood cultures are indicated for a sudden relative increase in patient's pulse rate and temperature, change in sensorium or blood pressure, chills, or prostration.
    2. Prolonged or intermittent and mild fever in association with heart murmur is also an appropriate indication.
    3. In general, any time bacterial, fungal, or mycobacterial sepsis is suspected, with the possible exception of minor mucocutaneous infections or of lower urinary tract infections.

II.    RECOMMENDATIONS

  1. Obtain cultures prior to initiation of antimicrobial therapy if possible.
  2. For bacterial or fungal sepsis, two cultures per patient collected by separate venipuncture is the standard for all adults and children, except in unusual circumstances (e.g., neonates). For mycobacterial sepsis, three cultures collected on separate days is recommended.
  3. Numerous studies have been published regarding both the appropriate volume and numbers of blood cultures. The consensus of experts is that, except in very unusual cases, no more than four sets of blood cultures should be collected in one 24-hour period. If all four sets are negative after 24 hours and sepsis is still suspected, more cultures may be collected.
  4. No more than four sets of blood cultures are to be accepted for culture by the laboratory each 24 hours (calendar day).
  5. Separate venipunctures are required for each set of cultures. Exceptions may occur, such as in the case of a patient having poor veins or a bleeding problem. In these cases, the blood cultures may be collected with a single venipuncture; however, this should be avoided if at all possible. In addition, for young pediatric patients, two cultures may be collected from one venipuncture if specifically requested by the attending clinician. The two separate volumes should still be collected as for two separate venipunctures.
  6. Severe life-threatening septicemia: Two cultures, taken by separate venipuncture, should be collected immediately before starting treatment. There is no benefit for delaying a second venipuncture by 30 minutes when taking two blood cultures. We require that the blood cultures be obtained in duplicate from two separate venipunctures at the same sitting; however, as previously noted, no more than four total cultures should be collected in a 24-hour period.
  7. Suspected SBE or low-grade intravascular infection: Four cultures should be taken within the first 24 hours at intervals. Timing is not critical. In other situations, timing is difficult because bacteremia may precede the onset of fever or chills.
  8. A larger number of cultures may have to be collected from persons already receiving antimicrobics. Cultures should be taken immediately before the next dose of parenteral antimicrobial agent.
  9. Infants and small children: Two blood cultures usually are sufficient (one may suffice in the neonate).

III.BLOOD CULTURES: DESCRIPTION AND OPTIONS

  1. One blood culture consists of a FAN (Fastidious Antibiotic Neutralization) aerobic and a FAN anaerobic bottle. For patients < 13 kg, either one FAN aerobic bottle or one Pediatric FAN bottle is used (see table).
  2. FAN aerobic bottle = 30 mL BacT Alert bottle (green cap).
    FAN anaerobic bottle = 40 mL BacT Alert bottle (orange cap).
    FAN pedatric bottle = 20 mL BacT Alert bottle (yellow cap)
  3. There are two routine methods of blood culturing:
    1. Routine blood culture: This is used for culture of both bacteria and yeast: Two BacT Alert bottles (FAN aerobic and FAN anaerobic).
    2. Isolator blood cultures (these should be collected by phlebotomists if possible):
      1. Routine isolator blood culture needs.
      2. Fungal isolator blood cultures are used for detection of dimorphic fungi (primarily Histoplasma).
  4. Legionella is routinely cultured by the Isolator method.
  5. AFB is cultured using the MB BacT blood culture bottle. If unavailable, collect in SPS or sodium heparin blood collection tube.
  6. Viral blood cultures: Lavender-top tube containing 7-10 ml of blood (EDTA anticoagulant).

IV.    COLLECTION OF ROUTINE BLOOD CULTURES

  1. Materials needed:
  1. BacT Alert Blood Culture Bottles
  2. Chlorhexadine scrubbing device (chlorhexaprep)
  3. Needle and syringe (one 20 ml syringe is sufficient per each adult blood culture set) or butterfly apparatus and 20 ml syringe
  4. Exam gloves

B. Procedure for the collection of routine blood cultures:

  1. Phlebotomist will don exam gloves.
  2. Apply a tourniquet and palpate arm for suitable vein.
  3. Release tourniquet.
  4. Prepare the blood culture bottles by applying labels and cleaning the tops with Chlorhexadine Sepp. Allow to air dry.
  5. Scrub the patient’s arm with a Chlorhexadine one-step Frepp applicator for 30 seconds. Use the three P’s technique (pinch, press, and prep).
  6. Allow the arm to dry for 60 seconds.
  7. Venipuncture using syringe.
    1. Remove syringe from package. Holding empty syringe, move plunger/barrel out and then push in as far as possible. This will serve to:
      1. Make it easier to draw plunger back when actually drawing blood, and
      2. Remove any excess air from the syringe.
    2. Place needle on syringe.
    3. Collect 20 ml of blood (if pediatric patient, volume of blood is determined by patient weight; refer to table). For mycobacteriology (AFB) cultures, collect 3-5 ml of blood.
    4. Remove needle and apply pressure.
    5. Without allowing needle to become potentially contaminated by touching bedding, etc., place syringe directly into one blood culture bottle. For routine blood cultures, distribute 10 ml into each bottle. If less than 20 ml and greater than 5 ml of blood is collected from an adult, distribute evenly between the two bottles. If 5 ml or less is collected from an adult, place the entire amount in the green aerobic bottle. Record the amount collected on the requisition slip.
    6. Discard needle and syringe in an appropriate manner.
    7. Bandage arm. Clean the top of the blood culture bottles with an alcohol wipe to remove any residual blood.
    8. Invert bottles so that clots will not form.
  8. Venipuncture using butterfly and syringe.

    The preferred method for collecting blood is the syringe method described above. In situations where other blood work is ordered, a butterfly apparatus may be used. Great care must be taken to ensure that no blood drips or splatters from the butterfly port.

  1. Insert butterfly needle into arm.
  2. Place 20 ml syringe on port. Collect 20 ml of blood (if pediatric patient, volume of blood is determined by patient weight. Refer to table).
  3. Remove syringe from butterfly. Place needle on syringe.
  4. Place syringe directly into one blood culture bottle. Distribute 10 ml into each bottle. If less than 20 ml and greater than 5 ml of blood is collected from an adult, distribute evenly between the two bottles. If 5 ml or less is collected from an adult, place the entire amount in the green aerobic bottle. Record total amount collected on the requisition slip.
  5. Clean the top of the blood culture bottles with an alcohol wipe to remove any residual blood.
  6. Proceed with any other blood drawing through the butterfly.
  1. Blood collection from Mediport and Broviac.
  1. Mediport: Clean and disinfect the skin as for a venipuncture and proceed to draw blood accordingly.
  2. Broviac:
    1. Clean the port with an alcohol wipe.
    2. Disinfect the port using Chlorosept applicator. Do not allow Chlorosept to pool in the stopper.
    3. Allow Chlorosept to dry for one minute and collect the specimen.
  1. Write the time of collection, date, type of stick (straight or butterfly) and your tech code on the requisition form. Blood cultures will not be accepted by the Microbiology laboratory unless all of this information is provided

C. Volume of blood to be collected for routine blood cultures:

  1. Adults: 20 ml of blood should be collected by syringe and equally divided between each BacT Alert bottle. If this amount cannot be obtained, a lesser amount may be used and equally divided between the bottles. (If 5 ml or less is collected, place the entire amount in the green aerobic bottle.) Notify the laboratory if this occurs by writing amount collected on the laboratory requisition form.
  2. Pediatrics: Collect as follows:
Weight
kg (lb)
Total Volume to Collect
Divide Among the Following
   

FAN BacT   Alert
(Aerobic) or
Pediatric Bottle

FAN BacT Alert (Aerobic)

FAN BacT Alert (Anaerobic)

< 1.5 (3.3)

1.0

X

   
< 4.0 (8.8)

1.0

X

   
4-13 (8.8-28.6)

3.0

X

   
13-25 (28.6-55.0)

10.0

 

X

X

> 25.0 (55)

20.0

 

X

X

3. Deliver bottles to the laboratory immediately so that incubation can be initiated. Be sure that the tech code of the phlebotomist is located on the requisition form. NOTE: Due to the critical importance of these culture results, every effort should be made to deliver inoculated blood culture bottles on the same day they are collected; however, if this is not possible, bottles must be kept at room temperature and delivered to the lab within 24 hours of collection.

V.    COLLECTION OF ISOLATOR BLOOD CULTURES

  1. This test is available from 0700 to 2300 hours daily.
  2. Isolator Specimen Collection
  1. General Information:
    Isolator blood culture tubes will be supplied when necessary.
  2. If patient weighs < 13 kg (28.6 lb), use pediatric Isolator. If patient weighs >13 kg, use adult Isolator tube.
  3. Blood should be collected directly into the Isolator tube. To avoid clotting, do not collect via butterfly needle if possible. A butterfly may be used when collecting Isolators when other blood work is ordered. Collect the Isolator first in this case.
  4. STRICT ASEPTIC TECHNIQUE is necessary for collection.
  5. CAUTION:Do not allow the contents of the tube to touch the yellow stopper in order to prevent the possibility of back flow of reagents from the tube which may cause an adverse patient reaction.
  6. CAUTION: The Isolator tube reagent can cause eye irritation if it contacts the eyes. If contact occurs, flush the eyes with water and seek medical attention.
  1. Materials Required:    Isolator tube - adult or pediatric
                                    Alcohol swab
                                    2% tincture of iodine
                                    Venipuncture supplies (Vacutainer)
  2. Collection Procedure (Adult and Pediatric):
    1. Prepare arm according to procedure for the collection of routine blood cultures (Section IV.B1.-B5).
    2. Disinfect stopper of the tube with a Chlorhexadine Prep Sepp.
    3. Collect blood using a vacutainer setup. Allow tube to fill completely. The patient's arm should be lowered so that the tube is lower than the needle to allow for complete fill.

      NOTE: Any tubes not completely filled must be approved by Microbiology. Lack of blood volume may cause EDTA toxicity and decrease recovery of some organisms.

    4. Invert the tube 4-5 times to prevent clotting and allow the red blood cells to be lysed.
    5. Label the tubes and request cards appropriately, making sure to record the time of collection and your tech code on the request card. Do not apply identification stickers to the Isolator tube. Write the patient information on the existing label.
    6. Transport to the lab as soon as possible. Use of the pneumatic tube system is NOT allowable as it may cause hairline cracks in the glass, which may lead to breakage during the high-speed centrifugation process used to process these tubes.

    4.    Rejection Criteria

    1. Isolator tubes that contain less than a full tube (10 ml of blood for adults; 1.5 ml of blood for pediatrics) may not be processed. Microbiology may reject the specimens depending on the circumstances.
    2. Extended delay in transport that would not allow processing within 16 hours of collection time will merit rejection.

    5.    Blood Culture Requests (examples of options available)

Test Requested

May Be Requested By

Please Collect Order and Chart As
Blood Culture Any physician BacT Alert Set Blood Culture (BLC)
Isolator Blood Culture2

Infectious Disease Service

1 Isolator Tube Blood Culture (BLC) Source: Isolator Blood
Fungus, Blood, for Histoplasmosis Infectious Disease Service 1 Isolator Tube Fungus Culture- Blood (FCB)
AFB Blood Culture Any physician MB BacT Blood Culture Bottle AFB Culture (AFBC)
Legionella Blood Culture Any physician 1 Isolator Tube Legionella Culture (LC)

1For pediatric patient weighing less than 13 kg (28.6 lb), collect single aerobic BacT Alert or Pediatric Isolator, as appropriate.

2This will usually be ordered along with routine (BacT Alert) Blood Cultures but should be a separate request.

VI.   HANDLING OF CULTURES

A. Storage of blood culture bottles:

  1. Clients may store limited amounts of blood culture bottles.
  2. Store the blood culture bottles in a cabinet in a secure, low-traffic area separate from storage of other nursing items. The outside of the cabinet must be labeled with identification of contents.

B. All BacT Alert bottles must be incubated at 35°C upon receipt in the testing laboratory.

C. Blood cultures are usually incubated for five days. Some organisms such as Brucella and certain streptococci may take longer than five days to grow. Brucella blood cultures are incubated for 21 days.

References:

Reller LB, Murray PR, and MacLowry JD. 1982. Cumitech IA: Blood Cultures II.. American Society for Microbiology, Washington DC.

Biomerieux. Durham, NC. BacT Alert Culture Bottle product insert, September 2003.

Biomerieux. Durham, NC. BacT Alert PF bottle product insert, October 2004.

Dupont. Wilmington, DE. Dupont Isostat Microbial System Resource Guide. 1987.

Washington, JA: 1985, p 27. Laboratory Procedures in Clinical Microbiology, 2nd ed. Springer Verlag, Princeton.