Collection of Blood Cultures

Collection of Blood Cultures

Blood Cultures are taken to identify patients with bacteraemia.  It is imperative that blood cultures are taken correctly to avoid contamination of the specimen from skin flora which may result in a positive blood culture that may not be clinically significant.  There are many signs and symptoms in a patient which may suggest bacteraemia and clinical judgement is required, but the following indicators (which may be subtle in the very young, the elderly, those on steroids or immuno-compromised) should be taken into account when assessing a patient for signs of bacteraemia or sepsis:

  • Pyrexia >38ºC
  • Focal signs of infection
  • Abnormal heart rate (raised), blood pressure (low or raised or respiratory rate (raised)
  • Chills or rigors
  • Raised or very low white blood cell count
  • New or worsening confusion

 

Please note: signs of sepsis may be minimal or absent in the very young and the elderly.

 

Only take blood for culture when there is a clinical need to do so and not as routine

Blood cultures should be taken after identification of possible bacteraemia or sepsis and before the administration of antibiotics.  If a patient is on antibiotics, blood cultures should ideally be taken immediately before the next dose and using a “Fan” aerobic bottle, with the exception of paediatric patients

All blood cultures should be documented in the patient’s medical notes. Documentation should include date, time, site (peripheral, central line, lumen, etc.), indication for blood culture and the name and bleep number of the person performing the procedure.

Blood Culture Collection Procedure

Step 1: Gather and prepare all materials required before beginning the procedure

Equipment required for blood culture collection:

  • Clean procedure tray with integrated sharps bin
  • Disposable tourniquet
  • Sterile needles, syringe and blood culture bottles, other blood bottles if required
  • Clinell wipe, or equivalent, *(2% chlorhexidine in 70% isopropyl alcohol impregnated swab)
  • Latex or Nitrile gloves
  • PPE – Plastic Apron/Goggles/Mask (required if risk of blood splash)
  • Appropriate sterile dressing  
  • Alcohol hand rub
  • Blood culture bottles. Ensure bottles are fully intact and within date.

-         Adult -  Use both an aerobic (blue top) and an anaerobic (purple top) bottle unless patient is already on antibiotics in which case  replace aerobic bottle with Fan (green top) bottle.

-         Child –use Paediatric (yellow top) bottle.

* Prevention of Intravascular Catheter-related Infection in Ireland.  SARI Prevention of Intravascular Catheter-related Infection Sub-Committee.  Health Protection Surveillance Centre.  December 2009

Step 2: Prepare bottles for  inoculation

 

  • Wash hands with soap and water and dry or use alcohol hand rub on visibly clean hands
  • Remove the plastic ‘flip-caps’ from the blood culture bottle, avoid touching rubber septum, disinfect the tops of culture bottles (septum) for 15 seconds with a 2% chlorhexidine in 70% isopropyl alcohol impregnated swab (Clinell or equivalent). Allow the bottle tops to dry in order to fully disinfect. Use a fresh swab for each bottle.

Step 3:  Prepare venepuncture site

 

  • Confirm patient’s identity
  • Clean any visibly soiled patient’s skin with soap and water, then dry
  • Apply adisposable tourniquet and palpate to identify vein
  • Disinfect the skin for 30 seconds with a 2% chlorhexidine in 70% isopropyl alcohol impregnated swab (Clinell or equivalent) and allow to dry.  Do not palpate the site again after disinfection to prevent contaminating puncture site
  • If a culture is being collected from a central venous catheter, disinfect the access port with a 2% chlorhexidine in 70% isopropyl alcohol impregnated swab (Clinell or equivalent) and allow to dry

Step 4:  Sample collection using a needle and syringe

 

  • Wash and dry hands again or use alcohol hand rub and apply clean latex/nitrile gloves (sterile gloves are not necessary)
  • Insert needle into vein.  Do not palpate the site again after disinfection
  • Collect sample and release tourniquet.  (Up to 10ml for eachadult bottle. Up to 4 ml for paediatric.)
  • If blood is being collected for other tests, always inoculate the blood culture bottles first
  • Inoculate blood into culture bottles (already disinfected as in step 2 above). Do not change the needle between sample collection and inoculation.  Inoculate anaerobic culture first
  • Discard needle and syringe into the sharps container immediately after use. Dispose of blood stained items into clinical waste bag and decontaminate tray according to department practice
  • Cover the puncture site with an appropriate sterile dressing
  • Remove gloves and decontaminate hands
  • Record the procedure with indication for culture, time, site of venepuncture and any complications in the patient’s record along with name and bleep number of person who performed procedure

Step 5:  Sample management

 

  • Label bottles with appropriate patient information or use hospital addressograph label.  Ensure that barcodes on the bottles are not covered by additional labels.
  • Do NOT cover or remove peel-off barcode labels. These are vital for Laboratory use only
  • Complete microbiology request form giving the patient’s details to ensure compliance with the Patient Specimen and Request Form Identification Criteria, please supply clinical details and any antibiotics currently in use.  State on bottles and form if blood is from a peripheral vein or a central line
  • Place blood culture bottles in a sealed plastic specimen bag with the request form in the pouch

 

Blood cultures should be transported to the laboratory as soon as possible after collection