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:
Escalation order for blood culture sites, Intensive Care Unit:
Procedure: Gather equipment:
Prepare the blood culture bottles:
Patient preparation
Obtain the Culture: Collect using butterfly set and vacuette
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:
Number and Timing of Blood Cultures
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. |