Blood Culture Collection Protocols Quiz

Specimen Collection for Microbiological Studies

• Blood cultures are ordered when a patient's condition necessitates evaluating for bacteremia or septicemia.

• Poor aseptic technique or inappropriate specimen handling can result in either sterile or contaminated blood cultures.

• Known or suspected conditions like sepsis, meningitis, osteomyelitis, arthritis, endocarditis, peritonitis, pneumonia, or fever of unknown origin often require blood cultures.

• Blood cultures are a crucial diagnostic tool for identifying bacteremia or fungemia.

• The quality of blood specimens submitted for analysis significantly impacts accurate results.

• Bacteremia in adults is typically intermittent.

Important Considerations

• Blood specimens are critical for microbiological analysis.

• Blood culture is a highly sensitive method for identifying bacteremia or fungemia.

• Proper collection techniques and decontamination procedures are vital for accurate results.

• Initial collection protocol includes optimal collection and appropriate antiseptic precautions (standard decontamination methods).

• Decontamination involves using 70-95% alcohol, 2% chlorhexidine, or 1-2% tincture of iodine (TIO/Betadine) on the skin, with a 2-minute contact time.

• Multiple blood cultures (each with substantial blood volume) are necessary for detecting bacteremia. At least two sets of cultures from different venipuncture sites are ideal before administering antimicrobial therapy.

• The technique, number of cultures, and volume of blood are more crucial for accurate bacteremia detection than the exact timing of specimen collection.

• Skin flora can contaminate blood cultures and lead to false positives which can lead to misdiagnosis.

• Disinfection and avoiding existing intravenous lines diminish contamination, improving accuracy of results.

Technique

• Sterile technique is critical to prevent contamination of blood culture media by skin flora during collection.

• Skin flora can cause systemic disease; inaccurate results occur where blood cultures are contaminated.

• Proper disinfection of the venipuncture site and avoiding existing intravenous lines is essential to minimizing blood culture contamination.

• Apply a tourniquet, locate the phlebotomy site, and use a chlorhexidine solution or 2-3 alcohol swabs to clean the area. Allow to dry for at least 30 seconds.

• Wear sterile gloves. Use a firm scrubbing motion for 30 seconds to disinfect the 10 cm area of skin. Allow to dry again at least 30 seconds before venipuncture.

• Povidone-iodine swabs are more effective than chlorhexidine alone for skin decontamination.

• Avoid touching the venipuncture site after preparation. If palpation is needed, apply sterile gloves.

• Withdraw appropriate blood volume.

• Draw blood cultures before other blood samples.

• Keep hands sterile (especially the dominant hand). Alcohol pads should be removed from the top of the culture bottles immediately.

• Inoculate culture bottles (8-10 ml per bottle), using properly marked indicator lines. Volumes are different for pediatric samples compared to adult samples.

• Remove the tourniquet and butterfly needle, cover with gauze dressing, and apply pressure as needed.

• Label the bottles in the patient's presence, avoiding covering bar-coded areas.

• Fill out the Microbiology-routine lab slip.

• Indicate suspected diagnosis.

• Document date and time of collection.

• Document cultures obtained on the correct nursing form and send to the lab as soon as possible.

• Do not refrigerate blood cultures.

Suspected Catheter Sepsis

• Two sets of blood cultures. One from the suspected catheter and one from a separate peripheral site.

• Time of collection should be documented for each specimen.

• Remove a section of catheter (about 1 inch).

• Send the catheter section and concomitant blood cultures to the microbiology lab in a dry sterile container.

Acute Endocarditis

• Draw 2-3 blood cultures from separate sites within 30 minutes. Samples should be drawn before initiating antibiotic therapy.

• Begin antibiotic therapy after obtaining cultures.

Subacute Endocarditis

• Draw 2-3 blood cultures on Day 1, spaced 30-60 minutes apart.

• Additional sets can be drawn on Days 2 and 3 (maximum 4 sets in 24 hours) if negative, as help to document continuous bacteremia.

• Immediate antibiotics are less important than confirming the specific microbial diagnosis

Fungal Cultures

• Follow routine procedure for bacterial cultures if fungal cultures are ordered.

Bone Marrow

• Wear the appropriate personal protective equipment during bone marrow collection.

• Prepare the skin as for blood cultures.

• Aspirate the marrow percutaneously using a sterile needle and syringe, and transfer 3-5 ml into a separate blood culture bottle.

• Do not place the bone marrow sample in a heparin tube. Instead, send AFB and fungal cultures separately in separate mycobacteria/fungal blood culture bottles.

• Transport immediately at ambient temperature.