BLOOD CULTURE

• Systemic signs indicate bloodstream infection
• systemic inflammatory response syndrome, severe sepsis or septic shock
• rigors or new confusion with or without evidence of localised infection
• Patients with severe sepsis, especially the elderly or immunocompromised, may not have a fever
• do not restrict blood culture specimens to patients who ‘spike a fever’ (>38°C)
• If secondary infection with a new pathogen suspected or if antimicrobials seem ineffective, repeat blood cultures

How many sets?

• Collect blood culture specimens before starting antimicrobial drugs

Sepsis

• 2 sets of blood culture specimens in first hour before starting antimicrobials
• remember to start empiric antibiotic treatment immediately after blood cultures are taken

Suspected endocarditis

• 3 sets of blood culture specimens at different times in 24 hr
• interval depending on the urgency to start empiric antibiotic treatment (e.g. SBE: 8 hr; acute IE: 20 min). See Infective Endocarditis

• Hand wash
• Disposable apron
• Gloves
• Disposable tourniquet
• Injection tray (blue plastic tray)
• 2 Clinell cleansing wipes (2% chlorhexidine in 70% isopropyl alcohol)
• 1 for skin and 1 for top of blood culture bottles
• Sterile gauze
• Sticking plaster/tape
• Sharps bin
• Microbiology laboratory request form

Blood collection equipment

• Blood culture bottles
• each set of blood cultures comprises 2 bottles – 1 aerobic and 1 anaerobic
• If available, use vacuum-assisted blood collection system to reduce risk of needle-stick injury
• One winged butterfly with extension tube to draw blood directly into blood culture bottles
• mark each blood culture bottle for 10 mL volume to ensure correct amount of blood goes into bottle
• If venous access difficult, use a minimum 20 mL sterile syringe and needle to obtain sample and inoculate blood culture bottles using the same needle
• If IV central line present, obtain blood culture from both peripheral venous access and central line
• In rare instances, where no peripheral venous access available, sample from IV central line(s) only
• use a syringe for drawing blood
• attach a sterile needle to inoculate blood sample into blood culture bottles

• If not competent in procedure, organise supervision by a clinician experienced in the procedure

Patient

• Consider any pre-existing medical condition and current medication

Consent

• Identify patient
• Explain procedure
• Obtain and record consent – see Consent guideline

Collect equipment

• Take equipment (listed above) to patient’s bedside

Procedure

• Wash hands with soap and water and dry with disposable paper towel. See Hand hygiene guideline
• Put on apron

Prepare blood culture bottles

• Check expiry date
• If using winged butterfly system, to avoid false positive results, mark bottles to ensure 10 mL of blood not exceeded
• Flip off plastic lids
• Use a Clinell wipe to clean septum of each bottle
• allow alcohol to fully evaporate/dry before inoculation of blood

Select sampling site

• Select venepuncture site
• percutaneous peripheral vein (non-cannula) blood samples are the best source of contamination-free cultures
• use femoral vein only if venepuncture not possible at other sites
• use cannula (e.g. arterial line, central line) samples for blood culture ONLY when no other option or for evaluation of line sepsis
• Inspect and palpate the site without or with a tourniquet
• if tourniquet applied, remove it and re-apply when commencing procedure

Prepare skin

• Cleanse hands
• Put on gloves
• Apply disposable tourniquet
• Cleanse patient’s skin with cleansing wipe from blood culture pack following manufacturer’s instructions
• up/down and side to side over intended puncture site for a minimum of 30 sec
• allow to dry for a minimum of 30 sec to kill bacteria on the skin
• Do not palpate the vein again after skin cleansing

Prepare equipment

• Vacutainer^® [winged needle with extension tube (butterfly)] with extension tube and vacutainer needle holder attached is the preferred and safest method
• secondary choice is syringe and needle method
• Remove sheath from needle

• Fill blood culture bottles first before collecting blood samples for any other tests
• reduces risk of contamination from non-sterile containers

Safety needle (straight or butterfly)

• Ensure bevel edge of needle is in upward position
• Anchor the vein by applying manual traction a few centimetres below proposed needle insertion site
• Insert needle smoothly at approximately 30° angle

Using vacutainer

• Ensure vacutainer set is stabilised and held safely
• Draw 8–10 mL of blood directly into aerobic bottle first, followed 8–10 mL into anaerobic bottle
• this avoids an exchange of air from the vacutainer extension line into the anaerobic bottle
• If sample insufficient, put 8-10mL of blood into the aerobic bottle and rest into the anaerobic bottle
• 98% of septicaemias are caused by aerobic or anaerobic organisms that can tolerate aerobic environments but an inadequate sample can give a false negative result
• Take any other blood tests

Using syringe

• Draw a minimum of 20mL blood into the syringe
• Transfer blood from syringe and needle, 8–10 mL of blood directly into aerobic bottle first, followed 8–10 mL into anaerobic bottle
• With remaining blood sample, fill the other blood bottles for additional tests

After blood collection

• Remove/release tourniquet
• Remove needle
• Apply pressure with gauze to puncture site
• If still oozing, apply hypoallergenic sticking tape over the sterile gauze

• Remove and safely dispose of sharps and equipment
• Remove apron and gloves
• Wash hands

Label and sign

• Blood culture bottles immediately at bedside
• patient name, NHS number and/or hospital number, date of birth, date and time sample taken, ward and consultant
• Sign label
• Remove any peel-off bar code labels from blood culture bottles and affix to lab request form
• do not stick any labels over remaining bar codes on blood culture bottles
• Complete pathology request form
• clinical data and details of antimicrobial therapy, date, time and site of sample, patient name, NHS number and/or hospital number
• Sign form

Transport

• Place bottles in microbiology request bag with completed laboratory request form
• Arrange transport of sample to microbiology laboratory
• do not use a pneumatic tube system to send blood culture bottles
• if there is likely to be a delay in transporting samples, keep the bottles at room temperature
• Document in medical notes, indication for sample, and that blood cultures have been taken, include:
• time and date sample taken and sent
• blood culture bottle bar codes
• sample site
• name and signature of person who took sample

Advice

• For treatment of sepsis, see Sepsis, severe sepsis and septic shock guideline
• For clinical advice on a septic patient, contact the duty consultant microbiologist