Blood cultures are used to detect infections in the bloodstream. It is a critical test where blood is injected into bottles containing culture media to grow any microorganisms present. It is important to collect blood cultures properly using sterile technique to avoid contamination. The optimal method is to draw at least 10ml of blood from a vein and inject equal amounts into aerobic and anaerobic bottles. It is also important to label the cultures properly and provide relevant patient information.

1. COLLECTION OF BLOOD FOR
CULTURING
Dr.T.V.Rao MD
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2. 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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3. 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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4. 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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5. Blood culturing most important
and life saving Investigation
Needs optimal Methods for
Diagnosis of Blood Borne Pathogens
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6. 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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7. 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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8. 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
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9. 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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10. 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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11. 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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12. 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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13. 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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14. The requisitions form should be completely filled
out, and the requisition must indicate the tests
ordered.
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15. Self Protection
A few ways to make sure your
role in the collection process is
carried out with
efficiency, orderliness and safety
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16. 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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17. 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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18. . Barrier protection for the phlebotomist
consists of the latex gloves.
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19. 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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20. 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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21. 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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22. The vein is anchored and the needle
is inserted.
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23. The vacutainer tube is depressed into the
needle to begin drawing blood
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24. 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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25. When the final tube is being drawn, release the tourniquet.
Then remove the tube, and remove the needle.
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26. After the needle is removed from the vein, apply firm pressure
over the site to achieve haemostasis.
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27. Apply a bandage to the area.
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28. 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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29. 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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30. 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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31. Label the tubes, checking the requisition for the proper
identification.
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32. 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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33. Document the Medical Records
• Document the
following in the
medical record:
• –Date & time
specimen obtained
• –Site of specimen
collection
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34. 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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35. 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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36. 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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37. 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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38. Visit me for more articles of interest in
Medicine and Health care please visit…
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39. • The programme created by Dr.T.V.Rao
MD as Technical Series for
Microbiologists in the Developing World
• Email
• doctortvrao@gmail.com
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