Standard Operating Procedure for Blood Culture Sampling in Adults  

• Aims
• Background and indications for standard operating procedure/protocol
• Protocol A. Using a needle safe vacuum-assisted blood collection system
• Protocol B. Technique for blood culture sampling via a vascular access devices
• Labelling and transport
• Documentation

Aims

• To standardise and optimise the blood culture technique for sampling from a peripheral vein in adults.
• To standardise and optimise blood culture technique for diagnosis of intravascular catheter-related bloodstream infection.

Back to top

1. Background and indications for standard operating procedure/protocol

The clinical features of bloodstream infection are varied and are not confined to a febrile illness. Blood cultures should only be taken when the results will directly affect patient management and may not be appropriate in some situations; for example patients on the end of life care pathway.

Blood samples for culture should be obtained whenever bloodstream infection is clinically suspected:

1. If there are symptoms or signs of systemic infection (e.g. fever, new acute confusion, rigors, new onset pain using CVAD etc).
2. Prior to starting any intravenous antibiotic treatment course.

Please complete the Sepsis Screening Tool found in PPM+ if NEWS>5 or 3 in one category and infection is a possible cause.  For advice on how to identify and appropriately respond to sepsis, including when to take blood cultures please see (link to sepsis guidelines and Neonatal Sepsis Guidelines)

Correct results of blood cultures (and hence, patient care and safety) rely on the person carrying out this test doing it properly; the test can fail to find microbes when they are present (false negative) or find bacteria that were not in the bloodstream (false positives) if it is not done correctly. False positives result in patients receiving antibiotics they don’t need, and false negatives can result in patients not receiving antibiotics they do need.

Back to top

2. Protocol A. Using a needle safe vacuum-assisted blood collection system

Procedure method (step by step)

Blood culture technique for sampling from a peripheral vein in adults.

Before you begin:

• Do not use existing peripheral cannula or sites immediately above peripheral cannulae.
• Do not routinely use a newly inserted cannula. This should only be considered appropriate if a risk assessment has concluded that further peripheral venepuncture is not a suitable alternative e.g. needle phobia, patient non-compliance, etc.
• If following assessment the patient is considered to be restless, agitated or confused, gain assistance from a second person for the procedure.

Patient and equipment preparation for all blood samples.

• Wash hands with soap and water, in accordance with the LTHT Hand Hygiene policy
• Identify correct patient e.g. check name band and verbally confirm identity, explain the procedure and obtain verbal consent where appropriate.
• Clean the dedicated IV procedure trolley from top to bottom with detergent wipes and allow to dry, it is the drying process which kills the bacteria.
• Ensure you have all the equipment you will require. Check expiry dates and that packaging is intact.
• With each blood culture bottle held upright, mark where the liquid in the bottle comes to and, using the graded markers on the side of the bottle, also mark where it should be filled to in order to add 10ml of blood. (Figure 1)

Figure 1. Marking the blood culture bottle to guide filling volume.

Skin preparation

• Perform hand hygiene in accordance with LTHT Hand Hygiene policy and put on apron, ensure you are wearing appropriate face and eye protection. (see Standard Infection Prevention and Control Precautions)
• Open a dressing pack carefully ensuring only the corners are touched with your un-gloved hands to create a sterile field on the trolley. Secure yellow waste bag ready for use. Carefully open the safety collection device and drop onto the sterile field.
• Select a venepuncture site (NB Use the femoral vein only if venepuncture is not possible at other sites). If using femoral site clean the skin with soap and water, dry prior to decontamination; a 3ml SEPP will be required to clean the groin area.)
• Position the patient comfortably so selected site is easily accessible. Clean the venepuncture site using the Chloraprep Sepp. Apply with a cross hatch technique for at least 30 seconds. Allow to air dry (the drying process kills the bacteria).
• Perform hand hygiene.
• To avoid cross contamination from the collectors fingers it is important not to re-palpate the site once it has been disinfected.

Sample collection

1. Disinfect the non-sterile rubber tops of blood culture bottles using a swab containing 2% chlorhexidine gluconate in 70% alcohol (sani-cloth CHG 2%) (or alternative if patient has an allergy to Chlorhexidine). and place bottles to the side of the sterile field, not on it.
2. Apply a single patient use tourniquet at this point if required. Ensure you do not re-palpate your disinfected venepuncture site with ungloved hands.
3. Perform hand hygiene in accordance with LTHT Hand Hygiene in policy.
4. Put on sterile gloves.
5. Perform venepuncture ensuring asepsis is maintained as per LTHT aspesis policy  and secure butterfly needle to the patient’s skin with clean tape to ensure two hands are free to collect the sample. At this point your gloves are no longer sterile so do not touch venepuncture site or bottle tops.
6. With the blood culture bottle held upright insert the aerobic bottle first into the tube holder of the safety blood collection set. Blood will be sucked into the bottle by the vacuum, watch the level of liquid rise in the bottle and fill up to the mark you made to guide filling volume. Once the sample has reached the mark remove the bottle and repeat with the anaerobic bottle.
7. Remove tourniquet.
8. Place a swab over the venepuncture site and activate the safety feature of the safety blood collection set whilst applying gentle pressure to the puncture site. Press firmly over the venepuncture site until bleeding has ceased; the patient can be asked to do this if appropriate. Discard the needle into a sharps bin and remaining sterile pack in to clinical waste appropriately.
9. Remove apron and gloves, dispose into clinical waste bag, peform hand hygiene.
10. Clean trolley and return to dedicated storage area ensuring it is restocked if required.
11. If you were not able to fill the bottle with the planned volume*, estimate the volume of blood inoculated using the 5ml gradations (Figure 1) and record the volume of blood inoculated into each blood culture bottle, the time inoculated and label the request form and blood culture bottles as “peripheral”.

*If it is not possible to fill one or both bottles with at least 5ml of blood, repeat the above procedure at a different venepuncture site. If sterility is compromised at any stage during the procedure dispose of sample and repeat. A potentially contaminated sample must never be used to direct antimicrobial therapy.

Back to top

3. Protocol B. Technique for “paired” blood culture sampling to diagnose vascular catheter infection.

Before you begin:

• Sample blood via a peripheral vein as in Protocol A
• As soon as possible (within 30 minutes) of collecting the peripheral blood sample collect “through line” samples following this Protocol (B). Ensure the same volume of blood (that was inoculated into the peripheral set) is inoculated into the through-line sets and that the aerobic bottle is inoculated first.
• Stop all infusion/perfusion pumps and close all infusions, unless discontinuing an infusion is contra-indicated, for example inotropes or TPN within critical care.
• For long term lines (e.g. tunnelled lines, where infected line salvage may be attempted) obtain “through line” blood samples from every lumen wherever possible unless contra-indicated.
• For short term lines (intended use less than 2 weeks, e.g. Central Venous Catheters on ICU) please sample only from the most frequently accessed lumen.
• Record the volume of blood inoculated into each blood culture bottle, the time inoculated and label both request form and blood culture bottles as “Catheter [indicate lumen by colour]”.
• Please note: discard all rubbish into yellow bag or bottom of the trolley, never onto the top of trolley or sterile field.

You will need:

• At your designated IV preparation area draw up the required number of 0.9% sodium chloride flushes (10ml) using a Aseptic Non Touch Technique (ANTT) and place in dedicated clean tray. See guidelines for (Accessing an peripheral venous cannula to administer IV medication or accessing a central venous catheter to administer IV medication). For more information on ANTT please see Asepsis Policy.

“Through line” sample collection

1. Wash hands as per LTHT Hand Hygiene policy and put on apron.
2. Open a dressing pack/sterile dressing towel carefully ensuring only the corners are touched with your un-gloved hands to create a sterile field on the trolley. Secure yellow waste bag ready for use.
3. Carefully open all equipment onto sterile field, ensuring sterility is not compromised.
4. Wipe the rubber bungs of each blood culture bottle with the Sani-cloth CHG 2% and place on top of the trolley, away from other equipment.
5. Sanitize hands in accordance with LTHT Hand Hygiene policy
6. Put on clean gloves; these do not need to be sterile.
7. Holding the line up with one hand scrub the hub of the lumen with a 2.0 % chlorhexidine gluconate in 70% isopropyl alcohol wipe  - (Sani-cloth CHG 2%) for 15 seconds. Keep holding the hub while you allow 30 seconds for it to dry.
8. Do not draw and discard from the line prior to sampling. It is not necessary to discard the initial fluid in the lumen unless it is likely to contain an antibiotic.
   8a) If the patient has a line lock insitu, using the 10ml syringe to aspirate off the amount of lock insitu and no more. For example, if the lock is 2mls then only aspirate off 2mls of blood. Do not aspirate more than the line lock as this blood is essential for testing.
9. Attach a sterile in-situ line collection system (e.g. vacuette) to the decontaminated needle free hub using an aseptic non-touch technique. Be careful not to touch the tip of the collection device.
10. With the blood culture bottle held upright first insert the aerobic bottle into the collection device. Once the sample has reached the pre-marked fill level remove the bottle and repeat with the anaerobic bottle. If unable to bleed line please see techniques at the bottom of these instructions.
11. Using a non-touch technique flush the line with 10mls 0.9% sodium chloride.
12. Holding the line up with one hand scrub the hub of the lumen with a 2.0 % chlorhexidine gluconate in 70% isopropyl alcohol wipe again (Sani-cloth CHG 2%) for 30 seconds. Keep holding the hub while you allow 30 seconds for it to dry.
13. Repeat process for each of the lumen being sampled (if the patient has a long term line, see above).
14. Discard the collection systems into a point of use sharps bin and dispose of clinical waste appropriately.
15. Remove gloves and perform hand hygiene in accordance with LTHT Hand Hygiene policy.
16. Clean trolley and return to dedicated storage area ensuring it is restocked if required.

If unable to obtain blood from the CVAD use these techniques and repeat steps 7-12 before taking culture:

• Observe for kinks or damage on the line.
• Ask the patient to raise their arm slowly (the side of the CVAD).
• Ask the patient to lie flat.
• Ask the patient to cough.
• Flush the line with 2-3mls of sodium chloride 0.9% using the push/pause technique.

Back to top

Back to top

Documentation

Blood culture sampling, site, time and indication should be recorded in a clinical note on PPM or via the Sepsis Screening Tool.

Ensure that any subsequent positive results communicated by the microbiology department are accurately documented in the patient’s notes or on PPM+ and advice is acted on.