Background:

Properly obtained blood cultures are important to identify organisms and to ensure proper antimicrobial/antifungal coverage while minimizing false positive results.

Principle

Preparation of the skin for venipuncture is important to prevent contamination of blood cultures by bacteria that normally lie on the skin and to prevent introduction of these bacteria into the patient's bloodstream.

Patient Identification:

Follow the HFHS Patient Identification Policy (HFHS Administrative Policies - Clinical Practice) to properly identify the patient. Follow the Department of Pathology specimen labeling policy to properly label each bottle with patient identification and collect time and date before the blood is drawn.

Specimen Logistics

Blood cultures should be drawn prior to initiation of antimicrobial therapy.

Preparation of skin prior to blood culture collection is important to prevent contamination of sample.

At least two (2) sets of blood cultures should be obtained (each set includes one (1) aerobic and one (1) anaerobic bottle).

Each set of blood cultures are to be drawn from two separate venipuncture sites at approximately 15 minutes apart.

If two separate venipunctures are not able to be drawn, the provider must be notified, and collaboration should be done to determine if two sets are necessary.

Central lines (includes dialysis lines and Mediports) and Peripherally Inserted Central Catheters (PICCs) should not be used to obtain blood cultures due to the high probability of colonization and the likelihood of false positive results.

Central lines from outside facilities may be cultured for up to two (2) calendar days (as opposed to 48 hours), after admission by provider order only for a positive blood culture to be considered present on admission.

Blood culture volume is essential. There is a 3% increase in sensitivity for every extra mL collected. Blood culture bottles require 8- 10 mLs. to be accurate.

After positive blood cultures have been identified wait at least 48 hours to draw any additional blood cultures.

Surveillance blood cultures should not be routinely done.

KEY POINT: Neutropenic (ANC < 1500 µL) or thrombocytopenic (Platelets < 30,000 µL) patients suspected of having a blood stream infection are to have peripheral blood culture attempted twice before considering drawing a blood culture from a central line or PICC. It is imperative that cultures in these patients are drawn within an hour of suspected infection has been identified.

Do not send catheter tips for culture.

Escalation order of blood culture sites, General Practice Unit:

1. Peripheral venipuncture
2. Hospital Expert/IV team
3. Arterial puncture by Rapid Response team (if available)
4. Notify provider.

Escalation order for blood culture sites, Intensive Care Unit:

1. Peripheral venipuncture
2. Arterial Puncture
3. Unit Expert
4. Arterial line
5. Hospital Expert/IV team
6. Notify provider.

Procedure:

Gather equipment:

• Tourniquet
• 70% alcohol swab
• 2% Chlorhexidine with 70% isopropyl alcohol applicator
• Aerobic and anaerobic blood culture bottles
• Vacuette
• Butterfly set
• Clean Gloves
• Dressing
• Pen
• Labels

Prepare the blood culture bottles:

1. Remove cap and scrub the top of each blood culture bottle with a separate alcohol swab for 30 seconds
2. Allow to air dry
   • Do not fan or blow on tops once scrubbed.
   • Do not touch tops once scrubbed.

Patient preparation

1. Explain the procedure to the patient
2. Perform hand hygiene
3. Place tourniquet
   • Tourniquet should not remain on patient for longer than 1 minute
4. Palpate and select site prior to cleansing skin
5. Remove tourniquet

Obtain the Culture: Collect using butterfly set and vacuette

1. Assemble blood culture drawing equipment and arrange supplies needed.
2. Perform hand hygiene.
3. Put on clean gloves.
4. Place tourniquet.
5. Cleanse skin with 2% Chlorhexidine with 70% isopropyl alcohol applicator for 30 seconds using back and forth scrubbing technique
   • Allow to dry for at least 30 seconds (skin must be dry prior to venipuncture).
   • Do not fan or blow on skin once cleansed.
   • Do not palpate site once cleansed.
6. Perform venipuncture. Venipuncture should be performed using butterfly set and vacuette.
7. Fill aerobic bottle first then anaerobic bottles (Appendix A for correct volume appropriateness).
8. Fill until 10mLs is obtained in each bottle. Watch volume as bottle may overfill.
9. Remove tourniquet.
10. Hold pressure and place dressing.
11. Remove gloves.
12. Perform hand hygiene.
13. Label cultures with bedside labeling device or handwrite the site of draw on label while at the patient’s bedside. (See Appendix B).
14. Send to lab per operational unit policy.

Drawing Blood Cultures from vascular access device (VAD):

Blood should not be drawn from a VAD unless line related sepsis is suspected. Confirm that MD's order for blood culture specifies a line draw. Blood cultures drawn from lines are more likely to be contaminated therefore adequate precautions should be taken to avoid contamination. If drawing a blood culture from a VAD, it should always be accompanied by a blood culture from peripheral site.

See appropriate nursing guidelines for drawing blood from VADs. Follow instructions for bottle preparation and blood culture volume as outlined previously. Use alcohol prep to scrub hub connection with 70% alcohol and allow to air dry. Bottle cannot be drawn directly without the use of an adapter.  Contact laboratory is assistance is needed.

If unable to obtain peripheral blood culture and a culture from an IV line needs to be done, these steps must be followed for drawing blood cultures from peripheral IVs, Central Lines and PICCs:

1. Remove needleless connector and place a new sterile one
   • Never draw from an old connector
2. Scrub the hub with 70% alcohol swab for at least 30 seconds and allow to dry
   • Do not fan or blow on connector once cleansed
3. Contact lab for any additional adapters as bottle cannot be drawn directly from site.
4. Do not draw more than one set from this access
5. If another set is needed wait 15 minutes change needless connector and repeat the process

Number and Timing of Blood Cultures

Condition	Recommendations
Suspected acute primary bacteremia or fungemia, meningitis, osteomyelitis, arthritis, or pneumonia	Obtain 2 sets at the same time by separate venipuncture immediately following the clinical events that precipitate the blood culture.
Fever of unknown origin	Obtain 2 to 3 blood culture sets initially at the same time by separate venipuncture.  Then, 24 to 36 hours later, obtain two more sets of cultures immediately before the expected (usually afternoon) temperature elevation.
Suspected bacteremia or fungemia with persistently negative blood cultures	Consider alternative blood culture methods designed to recover rare or fastidious microorganisms (e.g. Isolator tube)
Infective endocarditis	Obtain 4 blood culture sets during the first 1-2 hours of evaluation.  If all are negative 24 hours later, obtain 4 more sets.  From patients who have received antimicrobial agents within 2 weeks prior to admission, obtain two separate blood cultures on each of three successive days.  Request extended incubation if Brucella or Bartonella is suspected.

Transport to the Lab

Pneumatic tube: To send blood culture bottles by pneumatic tube, place each bottle in a biohazard bag.  Seal the bags and place the requisition slips (if not preordered) in the outside pocket of one of the bags. Place the bottles in the carrier so that the bottoms of the bottles are end to end in the center of the carrier and the necks of the bottles face outward.  Other specimen tubes may be placed in the carrier with the blood culture bottles as room permits.

Regular courier: Use two specimen bags.  Wrap one bottle snuggly with a plastic specimen transport bag and insert the wrapped bottle in another plastic transport bag. Place the second bottle of the set in the bag.  Seal the bag and place requisition slips (if not pre-ordered) in the outside pocket. 

Instructions for local laboratory sending blood cultures to Core Microbiology laboratory

If there is no scheduled courier within 4 hours of blood culture receipt in the laboratory, contact A1 cab for transport to core laboratory. This may require calling A1 cab more than once per day for blood cultures particularly during large gaps between scheduled courier runs. Use of A1 cab for specimen transport can be minimized by strategically scheduling A1 use (example: schedule A1 cab to arrive in the middle of an 8 hour gap between scheduled courier runs). If A1 is contacted to pickup blood culture specimens, any additional microbiology specimens pending transport should also be sent along with batch list.

Reference(s)/Source(s):

Clinical Key “Blood specimen collection: Blood cultures” accessed 7/12/18.

Wiggers JB, Xiong W, Daneman N. Sending repeat cultures: is there a role in the management of bacteremic episodes? (SCRIBE study). BMC infectious diseases. 2016 Dec; 16(1):286.

Wilson ML, Mitchell M, Morris AJ, Murray PR, Reimer LG, Reller LB, Towns M, Weinstein MP, Wellstood SA, Dunne JW, Jerris RC. Principles and procedures for blood cultures; approved guideline. CLSI document M47-A. Clinical and Laboratory Standards Institute, Wayne, PA. 2007.