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COLLECTION OF BLOOD FOR CULTURING

Dr.T.V.Rao MD

What is a Blood Culture?

• A blood culture is a laboratory test in which blood is injected into bottles with culture media to determine whether microorganisms have invaded the patient’s bloodstream.

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Need for Blood Culture?

No microbiological test is more essential to

the clinician than the blood culture. The

finding of pathogenic microorganisms in a

patient’s bloodstream is of great importance

in terms of diagnosis, prognosis, and therapy.” - L. Barth Reller, Clin. Infect. Diseases, 1996

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Blood Culture is done to Detect Infectious Diseases

• Blood culture is a microbiological culture of blood. It is employed to detect infections that are spreading through the bloodstream (such as bacteremia, septicemia amongst others). This is possible because the bloodstream is usually a sterile environment

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Blood culturing most important and life saving Investigation

Needs optimal Methods for Diagnosis of Blood Borne Pathogens

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Blood Collection

• Aseptic collection procedure is critical Amount of blood– 1:10 ratio of

blood to broth– Younger than 10

years – 1 ml of blood for every year of life

– Over 10 years – 20 ml

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Blood Collection

• Frequency of Collection– Depends if bacteremia

is transient, intermediate or continuous

– Number of cultures collected are usually inversely related to the type of bacteremia

– Usually x3 from different body sites

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Blood Culture Methods• Conventional Broth Systems

–One aerobic bottle and one anaerobic bottle per blood collection–Aerobic broth contains soybean casein digest broth, Tryptic or trypticase soy broth, Brucella agar or Columbia broth base–Anaerobic broth is usually the same as aerobic with addition of 0.5% cysteine in an aerobic environment–Must be subcultured and gram stained manually

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Venipuncture• Venipuncture is the process of obtaining

intravenous access for the purpose of intravenous therapy or obtaining a sample of venous blood. This procedure is performed by medical laboratory scientists, medical practitioners, some EMTs, paramedics phlebotomists and other nursing staff. Venipuncture is one of the most routinely performed invasive procedures and is carried out for two reasons, to obtain blood for diagnostic purposes or to monitor levels of blood components (Lavery & Ingram 2005).

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Phlebotomy Definition

• phle·boto·my (fli) noun the act or practice of bloodletting as a therapeutic measure

• Phlebotomy from Greek words, phlebo, relates to veins, tomy, relates to cutting.

• Opening a vein to collect blood

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LABELING THE SAMPLE

– Properly labelled sample is essential so that the results of the test match the patient. The key elements in labelling are:• Patient's surname, first and middle.• Patient's ID number.• NOTE: Both of the above MUST match the

same on the requisition form.• Date, time and initials of the phlebotomist

must be on the label of EACH tube.

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Principles for Collection

• Gloves will be worn in accordance with standard precautions.

• •Appropriate verification of the patient's identity, by means of an armband or area specific procedure, will occur before the specimen collection.

• •Cultures should be drawn before administration of antibiotics, if possible. ???

• Blood cultures should not be drawn from lines, but should be drawn viavenipuncture.

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What Materials We need• Chlorhexidine swabs (1-2 packages)• Alcohol swabs• Blood culture bottles (2 bottles per set)• 2 syringes (adult: 20 cc, paediatric: 5 cc)• 2 needles (adult: 22 gauge or preferably larger butterfly

or standard needle; pediatric: 25 or 23 gauge butterfly or standard needle)

• Gloves (sterile &nonsterile)• Tourniquet• Sterile gauze pad• Adhesive strip or tape• Self-sticking patient labels• Plastic zip lock specimen bags

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The requisitions form should be completely filled out, and the requisition must indicate the tests ordered.

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Self Protection

A few ways to make sure your role in the collection process is carried out with efficiency, orderliness and

safety

Steps 1 – 3, Check, Explain, Wash

• 1.Identify the patient • 2.Explain the

procedure to the patient.

• 3.Wash hands with soap and water with friction for 15 seconds or use alcohol based hand rub

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Materials• Chlorhexidine swabs (1-2 packages)• Alcohol swabs• Blood culture bottles (2 bottles per set)• 2 syringes (adult: 20 cc, paediatric: 5 cc)• 2 needles (adult: 22 gauge or preferably larger butterfly or

standard needle; pediatric: 25 or 23 gauge butterfly or standard needle)

• Gloves (sterile &nonsterile)• Tourniquet• Sterile gauze pad• Adhesive strip or tape• Self-sticking patient labels• Plastic zip lock specimen bags

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. Barrier protection for the phlebotomist consists of the latex gloves.

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Obtaining Blood • Locate the vein• Prep kit

– Alcohol 5 sec. Dry 30-60 sec ( resource poor conditions )– Ideal to collect with alcohol swabs containing 2% Chlorhexidine

and 70% isopropyl alcohol

• Remove caps, clean with alcohol• Put on gloves• Without palpating, draw 20 ml and put 10

in anaerobic and 10 in aerobic bottle• Dispose of syringe in sharps container• Label bottles and send to lab

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Method of Blood Collection• A minimum of 10 ml of blood is taken

through venipuncture and injected into two or more "blood bottles" with specific media for aerobic and anaerobic organisms.

• The blood is collected using clean technique. This requires that both the tops of the culture bottles and the venipuncture site of the patient are cleaned prior to collection with alcohol swabs containing 2% Chlorhexidine and 70% isopropyl alcohol.

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The area of skin is cleaned with a disinfectant, or an alcohol swab.

• Using sterile gloves, do not wipe away the surgical solution, touch the puncture site, or in any way compromise the sterile process. It is vital that the procedure is performed in as sterile a manner as possible as the persistent presence of skin commensals in blood cultures could indicate endocarditis but they are most often found as contaminants

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The vein is anchored and the needle is inserted.

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The vacutainer tube is depressed into the needle to begin drawing blood

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Additional vacutainer tubes can be utilized. Determine what tests are ordered and what tubes will be necessary BEFORE you begin to draw

blood, and determine the order of draw for the tubes. .

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When the final tube is being drawn, release the tourniquet. Then remove the tube, and remove the needle.

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After the needle is removed from the vein, apply firm pressure over the site to

achieve haemostasis.

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Apply a bandage to the area.

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Preparation of Cap before Injecting Blood

• Prep the rubber cap of the blood culture bottles with an alcohol pad in a circular motion. Allow the alcohol to dry.

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Inject the Blood …..• Inject the blood

into the Selected Media

• Gently rotate the bottles to mix the blood & the broth (do not shake vigorously).

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Follow the universal precautions when disposing

Needle

• Dispose of needle in sharps container and dispose of other waste in proper container

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Label the tubes, checking the requisition for the proper

identification.

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Give the all possible Medical Information

• Patient’s name• • Hospital number (Patient ID)• • Patient’s location (room and bed #)• • Date and time of collection• • Collector’s initials• • Site of venipuncture• • Or other information as per facility• Include you Mobile Contact No – A vital information

can be delivered any time

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Document the Medical Records

• Document the following in the medical record:

• –Date & time specimen obtained

• –Site of specimen collection

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Frequency of Collection

• Frequency of Collection– Depends if bacteremia is

transient, intermediate or continuous

– Number of cultures collected are usually inversely related to the type of bacteremia

– Usually x3 from different body sites

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Second Set

• If 2 or more sets of blood cultures have been ordered, obtain the second set in the same manner as the first, making a new venipuncture at a different site.

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Newer Blood Culture Methods

• Newer Blood Culture Systems– Biphasic Broth-Slide System

• Agar “paddles” attached to top of bottle• Closed system

– Continuous Monitoring Blood Culture Systems• BacTec – measures 14CO2• BacTec 9000 Series – measures CO2• ESP – measures consumption of gases• BacT-Alert – measures change in pH

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The Contaminated Blood Culture

• If the skin is not adequately cleansed before drawing blood for culture, bacteria on the skin will be injected into the bottle, producing a false positive blood culture

• It is difficult for the physician to determine whether the bacteria growing in the blood culture is a real pathogen causing bloodstream infection or whether bacteria on the skin have contaminated the culture. This can lead to excess use of antibiotics and prolongation of hospital stay.

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