BLOOD CULTURE
A key investigation for
diagnosis of bloodstream infections
INTRODUCTION
Dr Susan M. Novak-Weekley
Ph.D. D(ABMM), S(M)ASCP
Vice-President, Medical Aff airs,
Qvella, Carlsbad, CA, USA
Wm. Michael Dunne, Jr.
Ph.D. D(ABMM), F(AAM, CCM, IDSA, PIDJ)
Senior Fellow, Clinical Microbiology, Data Analytics Group,
bioMérieux, Inc., Durham, NC, USA
Adjunct Professor of Pathology and Immunology,
Washington University School of Medicine,
St. Louis, MO, USA
Adjunct Professor of Pediatrics,
Duke University School of Medicine,
Durham, NC, USA
for their helpful advice and comprehensive review
of this booklet.
OUR SPECIAL THANKS GO TO
The laboratory detection of bacteremia and fungemia using blood cultures
is one of the most simple and commonly used investigations to establish the
etiology of bloodstream infections.
Rapid, accurate identification of the bacteria or fungi causing
bloodstream infections provides vital clinical information required to
diagnose and treat sepsis.
Sepsis is a complex inflammatory process that is largely underrecognized as a major cause of morbidity and mortality worldwide. There are
an estimated 19 million cases worldwide each year,(2) meaning that sepsis
causes 1 death every 3-4 seconds. (3)
Early diagnosis and appropriate treatment make a critical diff erence when
it comes to improving sepsis patient outcomes. Chances of survival go down
drastically the longer initiation of treatment is delayed. If a patient receives
antimicrobial therapy within the fi rst hour of diagnosis, chances of survival
are close to 80%; this is reduced by 7.6% for every hour after. Yet, if a patient
initially receives inappropriate antimicrobial treatment, they are fi ve times
less likely to survive. (4)
This booklet aims to:
answer key questions commonly asked in relation to blood culture
provide practical recommendations for routine blood culture procedures
off er an illustrated step-by-step guide to best blood culture collection
practices.
This booklet is intended to be a useful reference tool for physicians, nurses,
phlebotomists, laboratory personnel and all other healthcare professionals
involved in the blood culture process.
“…the laboratory detection of bacteremia and fungemia remains
one of the most important functions of clinical microbiology
laboratories... A positive blood culture establishes or confi rms that
there is an infectious etiology of the patient’s illness. Moreover,
it provides the etiologic agent and allows antibiotic susceptibility
testing for optimization of therapy.“ (1)
DEFINITIONS TABLE OF CONTENTS
Bacteremia: the presence of bacteria in the blood. It may be transient,
intermittent or continuous.
Blood culture: blood specimen submitted for culture of microorganisms.
It enables the recovery of potential pathogens from patients suspected of
having bacteremia or fungemia.
Blood culture series: a group of temporally related blood cultures that are
collected to determine whether a patient has bacteremia or fungemia.
Blood culture set: the combination of blood culture bottles (one aerobic and
one anaerobic) into which a single blood collection is inoculated.
Bloodstream Infection (BSI): an infection associated with bacteremia or
fungemia.
Contaminant: a microorganism isolated from a blood culture that was
introduced during specimen collection or processing and is not considered
responsible for BSI (i.e. the isolates were not present in the patient’s blood
when the blood was sampled for culture).
Contamination: presence of microorganisms in the bottle that entered
during sampling but were not actually circulating in the patient’s bloodstream.
Fungemia: the presence of fungi in the blood.
Sepsis: life-threatening organ dysfunction caused by a dysregulated host
response to infection. (5)
Septicemia: clinical syndrome characterized by fever, chills, malaise,
tachycardia, etc. when circulating bacteria multiply at a rate that exceeds
removal by phagocytosis. (6)
Septic episode: an episode of sepsis or septic shock for which a blood culture
or blood culture series is drawn.
Septic shock: a subset of sepsis in which underlying circulatory and cellular
metabolism abnormalities are profound enough to substantially increase
mortality. (5)
Source: Wayne, P.A. Principles and procedures for Blood Cultures; Approved Guideline, CLSI document M47-A. Clinical and
Laboratory Standards Institute (CLSI); 2007 unless otherwise specified.
2 3
BLOOD CULTURE ESSENTIALS p. 2
1 What is a blood culture? p. 4
2 Why are blood cultures important? p. 4
3 When should a blood culture be performed? p. 5
4 What volume of blood should be collected? p. 6
5 How many blood culture sets should be collected? p. 8
6 Which media to use? p. 10
7 Timing of blood cultures p. 11
8 How to collect blood cultures p. 12
9 How many days of incubation are recommended? p. 14
10 Is it a contaminant or a true pathogen? p. 15
SPECIAL TOPIC :
INFECTIVE ENDOCARDITIS p. 18
PROCESSING POSITIVE
BLOOD CULTURES p. 20
INTERPRETATION OF RESULTS p. 22
BLOOD CULTURE/
SEPSIS GUIDELINES p. 24
LIST OF ABBREVIATIONS p. 26
RECOMMENDATIONS
FOR BLOOD CULTURE COLLECTION p. 30
1
2
3
4
5
1 What is a blood culture?
A blood culture is a laboratory test in which blood, taken from the patient,
is inoculated into bottles containing culture media to determine whether
infection-causing microorganisms (bacteria or fungi) are present in the
patient’s bloodstream.
v Blood cultures are intended to:
Confi rm the presence of microorganisms
in the bloodstream
Identify the microbial etiology of
the bloodstream infection
Help determine the source of
infection (e.g. endocarditis)
Provide an organism for
susceptibility testing and optimization
of antimicrobial therapy
2 Why are blood cultures important?
Blood culture is the most widely used diagnostic tool for the detection of
bacteremia and fungemia. It is the most important way to diagnose the
etiology of bloodstream infections and sepsis and has major implications for
the treatment of those patients.
A positive blood culture either establishes or confi rms that there is an
infectious etiology for the patient’s illness. (3) A positive blood culture also
provides the etiologic agent for antimicrobial susceptibility testing, enabling
optimization of antibiotic therapy. (3) Sepsis is one of the most signifi cant
challenges in critical care, and early diagnosis is one of the most decisive
factors in determining patient outcome. Early identifi cation of pathogens in
the blood can be a crucial step in assuring appropriate therapy, and beginning
3 When should a blood culture be
performed?
Blood cultures should always be requested when a bloodstream infection or
sepsis is suspected.
v Clinical symptoms in a patient which may lead to
a suspicion of a bloodstream infection are:
undetermined fever (≥38°C) or hypothermia (≤36°C)
shock, chills, rigors
severe local infections (meningitis, endocarditis, pneumonia,
pyelonephritis, intra-abdominal suppuration…).
abnormally raised heart rate
low or raised blood pressure
raised respiratory rate
eff ective antibiotic therapy as early as possible can have a signifi cant impact
on the outcome of the disease. (8, 9)
v Providing adequate antibiotic therapy within
the fi rst 24-48 hours leads to: (10-14)
Decreased infection-related mortality (20-30%)
Earlier recovery and shorter length of hospital stay
Less risk of adverse eff ects
Reduced risk of antimicrobial resistance
Cost reduction (length of stay, therapy, diagnostic testing)
3 MAIN AIMS OF
BLOOD CULTURE *:
• Confi rm infectious etiology
• Identify the etiological agent
• Guide antimicrobial
therapy
0
Total patients (%)
Time to antibiotics
Patient survival rate (%)
Patients with eective antibiotic therapy
20
0 hours 1 2 3 4 5 6 9 12 24 36
40
60
80
100
Figure 1: Fast eff ective antimicrobial therapy increases survival chances
Adapted from Kumar A, et al. Crit Care Med. 2006;34(6):1589-96. (15)
* Adapted from ESCMID (European Society of Clinical
Microbiology and Infectious Diseases) guidelines, 2012. (7)
4 5
BLOOD CULTURE
ESSENTIALS
BLOOD CULTURE ESSENTIALS
1
vBlood cultures should be collected:
as soon as possible after the onset of clinical symptoms;
ideally, prior to the administration of antimicrobial therapy (16).
If the patient is already on antimicrobial therapy, recovery of microorganisms may be increased by collecting the blood sample immediately
before administering the next dose and by inoculating the blood into bottles
containing specialized antimicrobial neutralization media.
4 What volume of blood should be
collected?
The optimal recovery of bacteria and fungi from blood depends on culturing
an adequate volume of blood. The collection of a sufficient quantity of blood
improves the detection of pathogenic bacteria or fungi present in low quantities.
This is essential when an endovascular infection (such as endocarditis) is
suspected.
The volume of blood that is obtained for each blood culture
set is the most significant variable in recovering microorganisms from patients with bloodstream infections. (17, 18)
Blood culture bottles are designed to accommodate the recommended bloodto-broth ratio (1:5 to 1:10) with optimal blood volume. Commercial continuously
monitoring blood culture systems may use a smaller blood-to-broth ratio
(< 1:5) due to the addition of sodium polyanetholesulfonate (SPS) which
inactivates inhibitory substances which are present in blood. (3)
vAdults
For an adult, the recommended volume of blood to be obtained per
culture is 20 to 30 ml. (3, 16)
Since each set includes an aerobic and an anaerobic bottle, each bottle
should be inoculated with approximately 10 ml of blood. This volume is
recommended to optimize pathogen recovery when the bacterial/fungal
burden is less than 1 Colony Forming Unit (CFU) per ml of blood, which is
a common finding.
It is also generally recommended that two or three bottle sets (two bottles
per set) are used per septic episode, meaning, for adults, 40 to 60 ml of blood
collected from the patient for the 4 to 6 bottles, with 10 ml per bottle.
For each additional milliliter of blood cultured, the yield of microorganisms
recovered from adult blood increases in direct proportion up to 30 ml. (19) This
correlation is related to the relatively low number of CFU in a milliliter of adult
blood. (3)
vPediatric
The optimal volume of blood to be obtained from infants and children is less
well prescribed, however, available data indicate that the yield of pathogens
also increases in direct proportion to the volume of blood cultured. (16, 20)
The recommended volume of blood to collect should be based on the weight
of the patient (see Table 1), and an aerobic bottle should be used, unless an
anaerobic infection is suspected. (21)
Specially formulated blood culture bottles are commercially available for use
in children <2 years of age. They are specifically designed to maintain the
usual blood-to-broth ratio (1:5 to 1:10) with smaller blood volumes, and have
been shown to improve microbial recovery. (3)
Weight
of patient
Patient’s
total blood
volume
(ml)
Recommended
volume of blood
for culture (ml)
Total
volume for
culture
(ml)
%
of patient’s
total blood
volume
kg lb Culture
no.1
Culture
no.2
≤1 ≤2.2 50-99 2 2 4
1.1-2 2.2-4.4 100-200 2 2 4 4
2.1-12.7 4.5-27 >200 4 2 6 3
12.8-36.3 28-80 >800 10 10 20 2.5
>36.3 >80 >2,200 20-30 20-30 40-60 1.8-2.7
6 7
Table 1: Blood volumes suggested for cultures from infants
and children (20)
Adapted from Kellogg et al. Frequency of low-level bacteremia in children from birth to fifteen years of age.
J Clin Microbiol. 2000; 38:2181-2185.
BLOOD CULTURE ESSENTIALS BLOOD CULTURE ESSENTIALS
5 How many blood culture sets
should be collected?
Since bacteria and fungi may not be constantly present in the bloodstream,
the sensitivity of a single blood culture set is limited.
Using continuous-monitoring blood culture systems, a study investigated the
cumulative sensitivity of blood cultures obtained sequentially over a 24-hour
time period. It was observed that the cumulative yield of pathogens from
three blood culture sets (2 bottles per set), with a blood volume of 20 ml in
each set (10 ml per bottle), was 73.1% with the fi rst set, 89.7% with the fi rst
two sets and 98.3% with the fi rst three sets. However, to achieve a detection
rate of >99% of bloodstream infections, as many as four blood culture sets
may be needed. (22)
A contaminant will usually be present in only one bottle of a set of blood
culture bottles, in contrast to a true bloodstream infection, in which multiple
blood culture bottles/sets will be positive.
Therefore, guidelines recommend to collect 2, or preferably 3,
blood culture sets for each septic episode. (3, 7, 16)
If 2 to 3 sets are taken and cultures are still negative after 24-48 hours
incubation, and the patient is still potentially septic, 2 to 3 additional cultures
may be collected, as indicated in the following diagram. (16)
100%
90%
80%
70%
89.7%
20 ml 40 ml 60 ml
Detection sensitivity
73.1%
98.3%
A single blood culture bottle or set should never be drawn
from adult patients, since this practice will result in an inadequate volume of blood cultured and a substantial number
of bacteremias may be missed. (3, 22)
If culture is negative
after 24-48 h incubation
and patient is still
potentially septic without
an identifi ed source
Collect 2 to 3 sets
of bottles
(aerobic + anaerobic)
for each septic episode
Collect 2 to 3
additional sets of bottles
(aerobic + anaerobic)
Repeat protocol
if necessary
Prolong
incubation
Investigate
non-microbial
etiology
8 9
BLOOD CULTURE ESSENTIALS BLOOD CULTURE ESSENTIALS
Figure 2: Cumulative sensitivity of blood culture sets (22)
Adapted from Lee et al. Detection of Bloodstream Infections in Adults: How Many Blood Cultures Are Needed? J
Clin Microbiol. 2007; 45:3546-3548
Figure 3: Recommended number of blood culture sets
Adapted from Baron, E.J., et al. Cumitech 1C, Blood Cultures IV. Coordinating ed., E.J. Baron. ASM Press,
Washington, D.C. 2005
If culture is negative
after 24 h incubation
6 Which media to use?
Microorganisms causing bloodstream infections are highly varied (aerobes,
anaerobes, fungi, fastidious microorganisms…) and, in addition to nutrient
elements, may require specific growth factors and/or a special atmosphere.
In cases where the patient is receiving antimicrobial therapy, specialized
media with antibiotic neutralization capabilities should be used. Antibiotic
neutralization media have been shown to increase recovery and provide
faster time to detection versus standard media. (23-26)
7 Timing of blood cultures
Studies have shown that the time interval between collecting two blood
culture samples is not considered to be a critical factor as the diagnostic yield
remains the same. (7)
Guidelines recommend that the first two/three sets (2 bottles/set) of
blood culture be obtained either over a brief time period (e.g. within
1 hour) or as a single sample taken at one time. (3, 7, 16) The possible impact
that the blood culture collection method used (e.g. single or multiple
venipunctures, winged collection set or needle and syringe) may have on
contamination rates should be considered. (7)
Drawing blood at spaced intervals, such as 1 to 2 hours apart, is only
recommended to monitor continuous bacteremia/fungemia in patients with
suspected infective endocarditis or other endovascular (i.e. catheter- related)
infections. (16)
Two to three additional blood culture sets can be performed if the
first 2-3 blood cultures are negative after 24-48 hours incubation in cases
of severe infection or in order to increase detection sensitivity (in cases
of pyelonephritis for example). This also depends on the microorganisms
involved: while sensitivity is relatively good for organisms like Escherichia coli
or Staphylococcus aureus, it is lower for Pseudomonas aeruginosa, streptococci
or fungi. (28)
It is recommended that each adult routine blood culture set
include paired aerobic and anaerobic blood culture bottles.
The blood drawn should be divided equally between
the aerobic and anaerobic bottles.
If an anaerobic bottle is not used, it should always be replaced
by an additional aerobic bottle to ensure that a sufficient
volume of blood is cultured. (27)
vA blood culture medium must be:
sensitive enough to recover:
- a broad range of clinically relevant microorganisms, even the most
fastidious (Neisseria, Haemophilus…)
- microorganisms releasing small amounts of CO2 (Brucella,
Acinetobacter…)
versatile: able to provide a result for all types of sample collection
(adults, infants, patients receiving antibiotic therapy, sterile body fluids…)
vWhich bottle should be inoculated first?
If using a winged blood collection set, then the aerobic bottle should be
filled first to prevent transfer of air in the device into the anaerobic bottle.
If using a needle and syringe, inoculate the anaerobic bottle first to avoid
entry of air.
If the amount of blood drawn is less than the recommended volume*
, then
approximately 10 ml of blood should be inoculated into the aerobic bottle first,
since most cases of bacteremia are caused by aerobic and facultative bacteria.
In addition, pathogenic yeasts and strict aerobes (e.g. Pseudomonas) are
recovered almost exclusively from aerobic bottles. Any remaining blood should
then be inoculated into the anaerobic bottle. (8)
* For recommended volumes, see page 6 “What volume of blood should be collected?
10 11
BLOOD CULTURE ESSENTIALS BLOOD CULTURE ESSENTIALS
8 How to collect blood cultures
Sample collection is a crucial step in the blood culture process. Standard
precautions must be taken, and strict aseptic conditions observed
throughout the procedure. Compliance with blood culture collection
recommendations can significantly improve the quality and clinical value of
blood culture investigations and reduce the incidence of sample contamination
and “false-positive” readings.
1 Prior to use, examine the bottles for evidence of damage, deterioration
or contamination. Do not use a bottle containing media which exhibits
turbidity or excess gas pressure, as these are signs of possible
contamination.
2 Check the expiry date printed on each bottle. Discard bottles that
have expired.
3 Strictly follow the collection protocol in use in the healthcare setting,
including standard precautions for handling blood at the bedside.
4 Blood culture bottles should be clearly and correctly labelled,
including patient identification, date and collection time, puncture site
(venipuncture or intravascular device).
5 Each blood culture set should include an aerobic and an anaerobic
bottle.
6 Blood for culture should be drawn from veins, not arteries.
(30)
7 It is recommended to avoid drawing blood from a venous or arterial
catheter, since these devices are often associated with higher
contamination rates. (31)
12 13
BLOOD CULTURE ESSENTIALS BLOOD CULTURE ESSENTIALS
8 Carefully disinfect the skin prior to collection of the sample using an
appropriate disinfectant, such as chlorhexidine in 70% isopropyl
alcohol or tincture of iodine in swab or applicator form. (3)
9 Transport the inoculated bottles and the completed blood culture
request to the clinical microbiology laboratory as quickly as possible,
preferably within 2 hours per CLSI. (3)
Any delay in testing the inoculated bottles may potentially lead to
an increased risk of false negative results. If delays are expected, it is
important to refer to the manufacturer’s Instructions for Use (IFU)
for guidance.
As an example for guidance regarding delays, the ESCMID guidelines
recommend that blood culture bottles for testing in continuous
monitoring systems should be stored temporarily at room temperature,
whereas bottles for manual testing should be incubated as soon as
possible. (32) Again, refer to the manufacturer’s IFU for guidance.
The use of vacuum tube transport systems can facilitate the rapid
transmission of bottles to the microbiology laboratory. However these
systems should be used with caution if using glass bottles. (33)
10 All blood cultures should be documented in the patient’s notes,
including date, time, collection site and indications.
10 Key Steps to Good Sample Collection:
For an illustrated step-by-step, see page 30.
A properly collected sample, that is free of contaminants,
is key to providing accurate and reliable blood culture results.
It is recommended that blood cultures should be collected only by members
of staff (medical, nursing, phlebotomist or technician) who have been fully
trained and whose competence in blood culture collection has been assessed. (29)
9 How many days of incubation
are recommended?
The current recommendation, and standard incubation period,
for routine blood cultures performed by continuous-monitoring
blood systems is fi ve days. (34)
However, published data suggest that three days may be adequate to recover
over 97% of clinically signifi cant microorganisms.
A study by Bourbeau, et al. (JCM, 2005) showed the number of signifi cant
microorganisms isolated per day for 35,500 consecutive blood cultures
collected over 30 months, of which 2,609 were clinically signifi cant isolates
and 1,097 were contaminants. (35)
These results demonstrate that 97.4% of clinically signifi cant isolates were
recovered within the first 3 days of incubation and 93.8% within
2 days of incubation.
vIncubation of Fastidious Microorganisms
Another study by Cockerill, et al. (CID, 2004) demonstrated that, when using
a continuous-monitoring blood culture system, 99.5% of non-endocarditis
bloodstream infections and 100% of endocarditis episodes were detected
within 5 days of incubation. (19) This data suggests that extended incubation
periods previously recommended for detection of the fastidious microorganisms*
that sometimes cause endocarditis, are no longer necessary
when using continuous-monitoring blood culture systems. (16)
* including Brucella, Capnocytophaga and Campylobacter spp., and the HACEK group (Haemophilus (except
H. infl uenzae) species, Aggregatibacter (previously Actinobacillus) species, Cardiobacterium hominis, Eikenella corrodens
and Kingella species) (36)
10 Is it a contaminant or a true pathogen?
Contamination of blood cultures during the collection process can produce
a signifi cant level of false-positive results, which can have a negative impact
on patient outcome.
A false positive is defi ned as growth of bacteria in the blood culture bottle
that were not present in the patient’s bloodstream, and were most likely
introduced during sample collection.
Contamination can come from a number of sources: the patient’s skin,
the equipment used to take the sample, the hands of the person taking
the blood sample, or the environment.
Collecting a contaminant-free blood sample is critical to
providing a blood culture result that has clinical value.
Certain microorganisms such as coagulase-negative staphylococci, viridansgroup streptococci, Bacillus spp, Propionibacterium spp., diphtheroids,
Micrococcus spp. rarely cause severe bacterial infections or bloodstream
infections. These are common skin contaminants, and a though they are
capable of causing serious infection in the appropriate setting, their detection
in a single blood culture set can reasonably be identifi ed as a possible
contaminant without clinical signifi cance. However, it is important to consider
that coagulase-negative staphylococci are the primary cause of both catheterand prosthetic device-associated infections and may be clinically signifi cant
in up to 20% of cases. (37)
The most diffi cult interpretation problem for the physician is whether the
organism recovered from a blood culture is a true pathogen causing
bloodstream infection, or a contaminant. If it is a contaminant, the patient
may be treated unnecessarily with antibiotics, leading to additional patient
risks. Interpretation of true pathogen versus contaminant should be based on
whether the blood has been collected with a venipuncture or an intra-vascular
device, and multiplicity of isolation of the same species. This illustrates
the crucial nature of having collection site information included with
the blood culture request sent to the laboratory.
Day 1
74.1%
19.7%
3.6% 1.7% 0.9%
Day 2 Day 3 Day 4 Day 5
80%
60%
40%
20%
0%
Figure 4: Clinically signifi cant isolates per day (35)
Adapted from Bourbeau PP et al. Routine incubation of BacT/ALERT®
FA and FN blood culture bottles for more
than 3 days may not be necessary. J Clin Microbiol. 2005;43:2506-2509
14 15
BLOOD CULTURE ESSENTIALS BLOOD CULTURE ESSENTIALS
In contrast to patients with infective endocarditis or other true positive
bloodstream infections, patients whose blood cultures grow contaminants
usually have only a single blood culture that is positive. This information is of
great practical value for physicians, and underlines the importance of taking
two to three blood culture sets from different anatomical sites. (16)
Contamination rates can be most effectively reduced by
strict compliance with hand hygiene rules and best practices
for blood collection, particularly during the stages of skin
antisepsis, venipuncture and sample transfer to blood
culture bottles.
However, even when the best blood collection protocols are used, it may not
be possible to reduce the contamination rate below 2%. (38) The American
Society for Microbiology and CLSI recommend targeting contamination rates
not exceeding 3% of the total of collected sets. (3, 16)
vImpact of contamination rates
A contaminated blood culture can result in unnecessary antibiotic therapy,
increased length of hospitalization and higher costs.
It has been found that each false positive result can lead to:
Increased length of stay - on average 1 day. (39)
39% increase in intravenous antibiotic charges. (39)
$5,000 to $8,720 additional charges. (40, 41)
20% increase in laboratory charges. (39)
3 days longer on antibiotics. (39)
Figure 5: Example of a laboratory-based algorithm to
determine blood culture contamination (42)
Adapted from Richter et al. Minimizing the workup of blood culture contaminants: implementation and evaluation of a laboratory-based algorithm. J Clin Microbiol. 2002;40:2437-2444.
Potential contaminant*
isolated from blood
culture
Additional draws +/-
48 hours?
Evaluation by
qualified personnel
Probable
contaminant;
AST** not performed
unless requested
Evaluation by
qualified personnel
Positive with same
organism?
Viridans group
streptococci?
Pathogen;
set up AST**
YES
YES
NO
NO
NO
YES
** Microorganisms such as coagulase-negative staphylococci, Streptococcus viridans, Bacillus spp,
Propionibacterium spp., diphtheroids, Micrococcus spp.
** AST: Antimicrobial Susceptibility Testing
16 17
BLOOD CULTURE ESSENTIALS BLOOD CULTURE ESSENTIALS
Blood culture is essential in the diagnosis of infective endocarditis
(infection of the heart valves). In this elusive disease, blood cultures may
need to be taken repeatedly during febrile episodes, when bacteria are
shed from the heart valves into the bloodstream. For patients with infective
endocarditis, positive blood cultures will be obtained in over 90% of
cases, if optimal culture conditions are respected. (43)
vAcute Infective Endocarditis
This is a fulminant illness progressing rapidly over days to weeks, which may
be caused by highly virulent pathogens, such as Staphylococcus aureus. When
suspected, the severity of this disease requires blood cultures to be drawn
immediately to avoid unnecessary delays in treatment.
Multiple blood culture sets should be drawn during a 30-minute
period prior to administration of empiric antimicrobial therapy. (44)
vSubacute Infective Endocarditis
If sub-acute infection is suspected, there is usually not an urgent need to
initiate empiric therapy. It is more important to attempt to establish the
microbiological diagnosis.
Multiple blood culture sets should be obtained prior to initiation of antimicrobial
therapy, with sets spaced 30 minutes to one hour apart. This may help
document a continuous bacteremia, and could be of additional clinical value. (3)
vFungal Infective Endocarditis
Once a rare occurrence, the incidence of fungal endocarditis is increasing
considerably. (45) Candida species are the most common fungal pathogens
involved in infective endocarditis. (46) If optimum collection conditions are
observed, the yield for positive blood cultures in fungal endocarditis for
Candida spp. is 83 to 95 %. (47)
vHow many cultures?
In order to distinguish between contamination and true bacteremia, a total of
three to fi ve blood culture sets should be suffi cient.
Initially, two to three blood culture sets should be obtained from patients with
suspected infective endocarditis. If the fi rst 2-3 sets are negative after
24-48 hours, collect two to three more sets of cultures. (3)
Often patients with suspected infective endocarditis have been put on antibiotics prior to blood collection. This is the most common reason for
“culture-negative” infective endocarditis. It is therefore important to use a
blood culture medium that has antimicrobial neutralization capacity in order
to sustain microbial growth in the presence of antibiotics (see page 10 “Which
media to use?”). (48, 49)
However, “culture-negative” endocarditis may also be due to fastidious
microorganisms, such as Aspergillus spp., Brucella spp., Coxiella burnetii,
Chlamydia spp. and HACEK*
microorganisms.
Since current continuous-monitoring blood culture systems can recover all
HACEK and other fastidious organisms within a 5-day period, extending
incubation beyond this period is no longer considered to be necessary.
However, if all blood culture bottles are negative after 5 days, and infectious
endocarditis is still suspected, all bottles should be subcultured to chocolate
agar. (50)
18 19
SPECIAL TOPIC:
INFECTIVE ENDOCARDITIS
SPECIAL TOPIC: INFECTIVE ENDOCARDITIS
2
Today, continuously-monitored blood culture systems provide the optimum
solution for blood sample processing. Generally accepted incubation periods
can vary from 5-7 days, with 5 days being most popular. (27) The study
discussed in Figure 4 shows that 98% of all positive specimens were detected
within the fi rst 3 days (see page 14). (35)
Patients who progress to septic shock have a 7.6% increase
in mortality every hour while not on appropriate therapy. (15)
Following an instrument-fl agged positive event, the bottle is removed from the
system and a Gram stain and subculture is performed.
If the sample is Gram stain positive, the morphology of the organism
should be reported immediately to the physician. Subcultures or rapid
techniques (e.g. molecular diagnostics) should be initiated immediately in
order to provide further organism identifi cation and antibiotic susceptibility
testing should be performed as soon as possible.
If a sample is Gram stain negative, no report is made to the clinician
unless there is growth on subculture.
A positive blood culture is a critical result and must be reported as soon as
available, due to the immediate impact on patient care decisions. When
reports are delivered rapidly, studies have shown broadly improved
outcomes and effi ciencies in patient management. (51, 52)
A study by Barenfanger, et al. (Am J Clin Pathol, 2008) validated that Gram
stains of positive blood cultures are a very important factor infl uencing
appropriate therapy and patient outcomes. The study documented a
statistically signifi cant increase in the mortality rate for patients who had
blood cultures processed after a delay (i.e. Gram stain performed ≥1 hour
after being detected as positive; P = 0.0389). The timely removal and reporting
of Gram stain results have a positive impact on patient care and this study
supports the need for 24/7 coverage of blood culture instruments. (53)
20 21
PROCESSING POSITIVE
BLOOD CULTURES
PROCESSING POSITIVE BLOOD CULTURES
Recent technological advances such as MALDI-TOF (Matrix-Assisted Laser
Desorption Ionization Time of Flight) provide the ability to rapidly deliver
definitive organism identification. Molecular diagnostics can identify
the most common pathogens in positive blood cultures as well as specifi c
antibiotic resistance genes associated with bloodstream infections. Rapid
identifi cation allows physicians to prescribe more targeted and eff ective
antimicrobial therapy earlier to positively infl uence outcomes. (54-56)
Additionally, antibiotic susceptibility testing techniques should be
performed on positive blood cultures to provide the clinician with
a complete result. Appropriate use of antibiotics is crucial in cases
of bloodstream infections and sepsis. Accurately determining the
antimicrobial resistance profi le of the causative pathogen in order to select
the most eff ective antibiotic therapy can have a signifi cant impact on patient
outcomes.
When processed correctly, blood cultures provide clinically
relevant information that can help improve patient outcomes,
decrease length of hospital stay and reduce use of antibiotics.
3
The microbiology laboratory can provide useful information to clinicians to
help them determine whether a blood culture sample is a true positive or a
false positive (contaminant). For example, the identity of the micro- organism
isolated can help determine if the culture is contaminated, and the number of
cultures positive with the same organism can help predict true infections. (57)
Time to positivity is also a factor used to determine potential contamination
as contaminants usually have a delayed (longer) time-to-detection due to a
lower overall bio-load.
Laboratories should consult with their medical director to create an
algorithm which helps determine whether or not an isolated organism is a
contaminant vs. an infective agent.
Models, such as the algorithm below, can give guidance only on the interpretation of blood culture results.
(42, 57, 58) These guidelines should be used
in conjunction with clinical guidelines, e.g. patient’s full blood count, presence
of catheters, radiological fi ndings, etc.
Figure 6: Example of interpretation algorithm for blood culture results
1
3
2
monomicrobial
culture
+
clinical symptoms
(e.g. endocarditis,
meningitis, pneumonia…)
polymicrobial culture
(from the appropriate
clinical setting
(e.g. transplants,
intraabdominal infection,
immunocompromized
patient…)
if pathogenic organism:
Listeria, S. aureus, Brucella,
Haemophilus,
Enterobacteriaceae, …
if normal skin fl ora:
Propionibacterium,
corynebacterium,
Bacillus,
coagulase-negative
staphylococci
if viridans streptococci
or coagulase-negative
staphylococci and
consistent with clinical
setting (e.g. indwelling
catheter, prosthetic
heart valve, immunocompromized patient)
More than one positive bottle Only one positive bottle
bloodstream infection probable
bloodstream infection
probable
bloodstream
infection
probable
bloodstream
infection
probable
contamination
Negative blood cultures
but clinical symptoms Repeat blood samples
Consider non-infectious etiology
Investigate viral etiology or
non-culturable microorganism
22 23
INTERPRETATION OF RESULTS
INTERPRETATION OF RESULTS
4
vInternational Guidelines
WHO guidelines on drawing blood: best practices in Phlebotomy.
World Health Organization 2010.
http://whqlibdoc.who.int/publications/ 2010/9789241599221_eng.pdf
Surviving sepsis campaign: international guidelines for management of severe
sepsis and septic shock: 2012.
Dellinger RP., et al. Crit Care Med. 2013;41:580-637.
http://www.survivingsepsis.org/guidelines/Pages/default.aspx
The Third International Consensus Defi nitions for Sepsis and Septic
Shock (Sepsis-3).
Singer M., et al. JAMA. 2016;315(8):801-810.
http://jama.jamanetwork.com/article.aspx?articleid=2492881
vNational Guidelines
COUNTRY/
REGION GUIDELINES
Australia Australia Clinical Excellence Commission Sepsis Kills
Program: Adult Blood Culture Sampling Guide v2 2012 SHPN
(CEC) 120077
http://www.cec.health.nsw.gov.au/__data/assets/pdf_
fi le/0005/259412/adult-blood-culture-sampling-guideline.pdf
Brazil Elmor de Araujo MR, Hemocultura: recomendações de coleta,
processamento e interpretação dos resultados, J Infect Control
2012; 1: 08-19
http://www.iqg.com.br/pbsp/img_up/01355393320.pdf
Europe European Society for Clinical Microbiology and Infectious
Diseases, European Manual for Clinical Microbiology,
1
st Edition, 2012.
https://www.escmid.org/escmid_library/manual_of_microbiology/
COUNTRY/
REGION GUIDELINES
France REMIC 2015. Automatisation des cultures microbiennes : quel
cahier des charges ? Chapitre 11
http://www.sfm-microbiologie.org/
Germany Reinhart K et al., Prevention, diagnosis, therapy and follow-up
care of sepsis: 1st revision of S-2k guidelines of the German
Sepsis Society (Deutsche Sepsis-Gesellschaft e.V. (DSG)) and
the German Interdisciplinary Association of Intensive Care and
Emergency Medicine (DIVI). German Medical Science, 2010,
Vol. 8: 1-86
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2899863/pdf/
GMS-08-14.pdf
South
Africa
Guideline for the optimal use of blood cultures. SAMJ 2010;
Vol. 100, No. 12: 839-843 SAMJ
http://www.fi dssa.co.za/Guidelines/Guideline_for_the_optimal_ use_of_
blood_cultures.pdf
UK UK Standards for Microbiology Investigations. Investigation
of Blood Cultures (for Organisms other than Mycobacterium species). Bacteriology | B 37 | Issue no: 8 | Issue date:
04.11.14 | Page: 1 of 51. Issued by the Standards Unit, Health
Protection Agency, PHE.
https://www.gov.uk/government/uploads/system/uploads/
attachment_data/fi le/372070/B_37i8.pdf
Taking blood cultures - a summary of best practice:
Saving lives reducing infection, delivering clean and safe
care. London: Department of Health; 2007.
http://webarchive.nationalarchives.gov.uk/20120118164404/hcai.dh.
gov.uk/fi les/2011/03/Document_Blood_culture_FINAL_100826.pdf
USA American Society for Microbiology: Cumitech 1C, 2005
(EJ Baron et al.) ASM Press
Clinical and Laboratory Standards Institute (CLSI®
),
document M47-A, Vol 27, 2007 (ML Wilson et al.)
Emergency Nurses Association (ENA). Clinical Practice
Guideline: Prevention of Blood Culture Contamination
https://www.ena.org/practice-research/research/CPG/Documents/
BCCCPG.pdf
E. Septimus. CDC Clinician Guide for Collecting Cultures. 2015
http://www.cdc.gov/getsmart/healthcare/implementation/clinician
guide.html
24 25
BLOOD CULTURE/SEPSIS
GUIDELINES
BLOOD CULTURE/SEPSIS GUIDELINES
5
1. Principles and procedures for Blood Cultures; Approved Guideline, CLSI document
M47-A. Clinical and Laboratory Standards Institute (CLSI); Wayne, P.A. 2007
2. Adhikari N.K.J., Fowler R.A., Bhagwanjee S., Rubenfeld G.D., Critical care and the global
burden of critical illness in adults. Lancet 2010;376:1339–1346
3. WSD fact sheet 2013/www.world-sepsis-day.org
4. Kumar, A, et al. Initiation of inappropriate antimicrobial therapy results in a fivefold
reduction of survival in human septic shock. Chest. 2009 Nov;136(5):1237-48
5. Singer M., et al. The Third International Consensus Definitions for Sepsis and Septic
Shock (Sepsis-3). JAMA. 2016;315(8):801-810
6. Koneman E.W., et al., Color Atlas and Textbook of Diagnostic Microbiology. Third Edition
7. European Society for Clinical Microbiology and Infectious Diseases, European Manual for
Clinical Microbiology, 1st Edition, 2012
8. Garey KW., Rege M., Manjunath P. Pai, Mingo DE., Suda KJ., Turpin RS., Bearden DT. Time
to Initiation of Fluconazole Therapy Impacts Mortality in Patients with Candidemia:
A Multi-Institutional Study. Clin Infect Dis. 2006;43(1):25-31
9. Khatib R., Saeed S., Sharma M., Riederer K., Fakih MG., Johnson LB. Impact of initial
antibiotic choice and delayed appropriate treatment on the outcome of Staphylococcus
aureus bacteremia. Eur J Clin Microbial Infect Dis. 2006;25(3):181-5
10. Kollef MH, Sherman G, Ward S, Fraser VJ. Inadequate antimicrobial treatment of
infections: a risk factor for hospital mortality among critically ill patients. Chest.
1999;115(2):462-74
11. Harbarth S., Garbino J., Pugin J., Romand J.A., Lew D., Pittet D. Inappropriate initial antimicrobial therapy and its effect on survival in a clinical trial of immunomodulating
therapy for severe sepsis. Am J Med. 2003;115(7):529–535
12. Lodise T.P., McKinnon P.S., Swiderski L., Rybak M.J. Outcomes Analysis of Delayed
Antibiotic Treatment for Hospital-Acquired Staphylococcus aureus Bacteremia. CID
2003:36:1419-1423
13. Kang C.I., Kim S.H., Kim H.B., Park S.W., Choe Y.J,. Oh M.D., Kim E.C., Choe K.W.
Pseudomonas aeruginosa bacteremia: risk factors for mortality and influence of
delayed receipt of effective antimicrobial therapy on clinical outcome. Clin Infect Dis.
2003;37(6):745-51
14. Forrest G.N., Mankes K., Jabra-Rizk M.A., Weekes E., Johnson J.K., Lincalis D.P., Venezia
R.A. Peptide Nucleic Acid Fluorescence In Situ Hybridization-Based Identification of
Candida albicans and Its Impact on Mortality and Antifungal Therapy Costs. J Clin
Microbiol. 2006 Sep; 44(9): 3381–3383
15. Kumar A, et al. Duration of hypotension before initiation of effective antimicrobial
therapy is the critical determinant of survival in human septic shock. Crit Care Med.
2006;34(6):1589-96
16. Baron, E.J., M.P. Weinstein, W.M. Dunne, Jr., P. Yagupsky, D.F. Welch, and D.M. Wilson.
Cumitech 1C, Blood Cultures IV. Coordinating ed., E.J. Baron. ASM Press, Washington, D.C.
2005
17. Mermel L.A., Maki D.G. Detection of bacteremia in adults : consequences of culturing an
inadequate volume of blood. Ann Intern Med. 1993;119:270-272
18. Bouza E, Sousa D, Rodríguez-Créixems M, Lechuz JG, Muñoz P. Is the volume of blood
cultured still a significant factor in the diagnosis of bloodstream infections? J Clin
Microbiol. 2007 45:2765-9
19. Cockerill FR III, Wilson J.W., Vetter E.A., et al. Optimal testing parameters for blood
cultures. Clin Infect Dis. 2004 ;38 :1724-1730
20. Kellogg J.A., Manzella J.P., Bankert D.A. Frequency of low-level bacteremia in children
from birth to fifteen years of age. J Clin Microbiol. 2000;38:2181-2185
21. Freedman S.B., Roosevelt G.E. Utility of anaerobic blood cultures in a pediatric
emergency department. Pediatr Emerg Care. 2004;20(7):433-6
22. Lee A., Weinstein MP., Mirrett S., Reller LB. Detection of Bloodstream Infections in Adults:
How Many Blood Cultures Are Needed? J Clin Microbiol 2007;45:3546-3548
23. Lee DH., Kim S.C., Bae IG., Koh EH., Kim S., Clinical Evaluation of BacT/ALERT FA Plus and
FN Plus Bottles Compared with Standard Bottles , J. Clin. Microbiol. 2013; 51(12): 4150-4155
24. Amarsy-Guerle R., Mougari F., Jacquier H., Oliary J., Benmansour H., Riahi J., Berçot B.,
Raskine L., Cambau E., High medical impact of implementing the new polymeric
bead-based BacT/ALERT®
FA Plus and FN Plus blood culture bottles in standard care, Eur
J. Clin. Microbiol Dis. 2015;34(5):1031-1037
25. Kirn T.J., Mirrett S., Reller L.B., Weinstein M.P., Controlled Clinical Comparison of BacT/
ALERT FA Plus and FN Plus Blood Culture Media with BacT/ALERT FA and FN Blood
Culture Media, J. Clin. Microbiol. 2014; 52(3): 839-843
26. Doern C., Mirrett S., Halstead D., Abid J., Okada P., Reller L.B. Controlled Clinical
Comparison of New Pediatric Medium with Adsorbent Polymeric Beads (PF Plus) versus
Charcoal-Containing PF Medium in the BacT/ALERT Blood Culture System, J. Clin.
Microbiol. 2014; 52(6): 1898-1900
27. Riley J.A., Heiter B.J., Bourbeau P.P. Comparison of recovery of blood culture isolates from
two BacT/ALERT FAN aerobic blood culture bottles with recovery from one FAN aerobic
bottle and one FAN anaerobic bottle. J.Clin. Microbiol. 2003;41:213-217
26 27
REFERENCES
28. Weinstein, M. P., M. L. Towns, S. M. Quartey, S. Mirrett, L. G. Reimer, G. Parmigiani, and L.
B. Reller. The clinical significance of positive blood cultures in the 1990s; a prospective
comprehensive evaluation of the microbiology, epidemiology, and outcome of
bacteremia and fungemia in adults. Clin. Infect. Dis. 1997;24:584–602
29. UK Department of Health: Taking Blood Cultures – A summary of best practice. 2007
30. Weinstein M.P. Current blood culture methods and systems: clinical concepts, technology, and
interpretation of results. Clin Infect Dis. 1996 ;23 :40-46
31. Everts R.J., Vinson E.N., Adholla P.O., Reller L.B. Contamination of catheter-drawn blood
cultures. J. Clin Microbiol. 2001;39:3393-3394
32. Cornaglia G., et al. European Manual of Microbiology. ESCMID-SFM 2012
33. Kirm T.J., Weinstein M.P. Update on blood cultures: how to obtain, process, report, and
interpret. Clin Microbiol Infect. 2013;19(6):513–520
34. Wilson M.L., Mirrett S., Reller L.B. et al. Recovery of clinically important microorganisms from the BacT/ALERT blood culture system does not require testing for
7 days. Diagn Microbiol Infect Dis. 1993;16:31-34
35. Bourbeau PP., Foltzer M. Routine incubation of BacT/ALERT FA and FN blood culture
bottles for more than 3 days may not be necessary. J Clin Microbiol. 2005;43:2506-2509
36. Clinical Infectious Disease. Edited by David Schlossberg. Cambridge University Press, 2015
37. Keri K. Hall and Jason A. Lyman, Updated Review of Blood Culture Contamination, Clin.
Microbiol. Rev. 2006, 19(4):788
38. Dunne W.M. Jr., Nolte F.S., Wilson M.L. Cumitech 1B, Blood Cultures III. Coordinating ed.,
Hindler J.A. ASM Press. Washington, D.C. 1997
39. Hall, K.K. and J.A. Lyman. Updated review of blood culture contamination. Clinical
Microbiology Reviews. 2006;19:788-802
40. Bamber, A.I., J. G. Cunniffe, D. Nayar, R. Ganguly and E. Falconer. The effectiveness of
introducing blood culture collection packs to reduce contamination. British Journal of
Biomedical Science. 2009;66(1):1-9.
41. Gander, R. M., L. Byrd, M. DeCrescenzo, S. Hirany and M. Bowen, J. Baughman. Impact of
blood cultures drawn by phlebotomy on contamination rates and health care costs in a
hospital emergency department. J. Clin. Microbiol. 2009;47:1021-1024
42. Richter S.S., Beekman S.E., Croco D.J., Koontz R.P., Pfaller M.A., Doern G.V. Minimizing
the workup of blood culture contaminants: implementation and evaluation of a
laboratory-based algorithm. J Clin Microbiol. 2002;40:2437-2444
43. Towns M.L., Reller L.B. Diagnostic methods: current best practices and guidelines for
isolation of bacteria and fungi in infective endocarditis. Infect Dis Clin N Am.
2002;16:363-376
44. Osborn TM., Nguyen HB., Rivers EP. Emergency medicine and the surviving sepsis
campaign: an international approach to managing severe sepsis and septic shock. Ann
Emerg Med 2005;46:228-231
45. Rubenstein E., Lang R. Fungal endocarditis. Eur Heart J. 1995; 16(Suppl B):84-89
46. Ellis ME., Al-Abdely H., Standridge A., Greer W., Venturea W. Fungal endocarditis:
evidence in the world literature, 1965-1995. 2001;32:50-62
47. McLeod R., Remington JS. Fungal endocarditis. In: Rahimtoola SH et al., eds.
Infective Endocarditis. New York, NY: Gune & Stratton.1978:211-290
48. Ziegler R., Johnscher I., Martus P., Lendardt D., Just HM. Controlled Clinical Laboratory
Comparison of Two Supplemented Aerobic and Anaerobic Media Used in Automated
Blood Culture Systems To Detect Bloodstream Infections. J Clin Microbiol.
1998;36:657-661
49. Pohlman JK., Kirkley BA., Easley KA., Basille BA., Washington JA. Controlled Clinical
Evaluation of BACTEC Plus Aerobic/F and BacT/ALERT Aerobic FAN Bottles for Detection of
Bloodstream Infections. J Clin Microbiol. 1995;33:2856-2858
50. Baron EJ., Scott JD., Tompkins LS. Prolonged incubation and extensive subculturing do
not increase recovery of clinically significant microorganisms from standard automated
blood cultures. Clin Infect Dis. 2005;41:1677-1680
51. Beekmann SE., Diekama D.J., Chapin KC., Goern GV. Effects of rapid detection of
bloodstream infections on length of hospitalization and hospital charges. J Clin
Microbiol. 2003;41:3119-3125
52. Munson E., Diekema DJ., Beekmann SE., Chapin KC., Doern GV. Detection and
treatment of bloodstream infection: laboratory reporting and antimicrobial management.
J Clin Microbiol. 2003;41:495-497
53. Barenfanger J, Graham DR, Kolluri L, Sangwan G, Lawhorn J, Drake CA, Verhulst SJ,
Peterson R, Moja LB, Ertmoed MM, Moja AB, Shevlin DW, Vautrain R, Callahan CD.
Decreased Mortality Associated With Prompt Gram Staining of Blood Cultures,
Am J Clin Pathol 2008;130:870-876
54. Timbrook T, Boger MS, Steed LL,Hurst JM, 2015. Unanticipated Multiplex PCR
Identification of Polymicrobial Blood Culture Resulting in Earlier Isolation, Susceptibilities, and
Optimization of Clinical Care. J. Clin. Microbiol. 2015;53(7):2371-3
55. Bauer KA, West JE, Balada Llasat J, Pancholi P, Stevenson KB, Goff DA. An Antimicrobial
Stewardship Program’s Impact with Rapid Polymerase Chain Reaction Methicillin
Resistant Staphylococcus aureus / S. aureus Blood Culture Test in Patients with
S. aureus Bacteremia. Clin. Infect. Dis. 2010;51(9):1074-1080.
56. Dierkes C, Ehrenstein B, Siebig S, Linde H-J, Reischl U, Salzberger B. Clinical impact of
a commercially available multiplex PCR system for rapid detection of pathogens
in patients with presumed sepsis. BMC Infect. Dis. 2009;9(1):126
57. Weinstein MP. Blood Culture Contamination: Persisting Problems and Partial Progress.
J Clin Microbiol. 2003;41:2275-2278
58. Weinstein MP., Towns ML, Quartey SM. et al. The clinical significance of positive blood
cultures in the 1990s: a prospective comprehensive evaluation of the microbiology,
epidemiology and outcome of bacteremia and fungemia in adults. Clin Infect Dis.
1997;24:584-602
59. Applied Phlebotomy. Dennis J. Ernst, Dennis J. Ernst (MT(ASCP)). Lippincott
Williams & Wilkins, 2005
60. Essentials Of Medical Laboratory Practice. Constance L Lieseke, Elizabeth A Zeibig. F.A.
Davis, 2012
61. Qamruddin A, Khanna N, Orr D. Peripheral blood culture contamination in adults and
venipuncture technique: prospective cohort study.J Clin Pathol. 2008 61:509-13
28 29
REFERENCES REFERENCES
RECOMMENDATIONS
FOR BLOOD CULTURE
COLLECTION
A SUMMARY
OF GOOD PRACTICE
30
A) USING WINGED BLOOD COLLECTION SET
(preferred method of collection)59, 60, 61
3 PREPARE VENIPUNCTURE SITE
If skin is visibly soiled, clean with soap and water. Apply a disposable tourniquet
and palpate for a vein. Apply clean examination gloves (sterile gloves are not
necessary).
Cleanse the skin using an appropriate disinfectant, such as chlorhexidine in
70% isopropyl alcohol or tincture of iodine in swab or applicator form. The
venipuncture site is not fully clean until the disinfectant has fully evaporated.
4 VENIPUNCTURE
Attach a winged blood collection set to a collection adapter cap*.
To prevent contaminating the puncture site, do not re-palpate the prepared
vein before inserting the needle. Insert the needle into the prepared vein.
5 CULTURE BOTTLE INOCULATION
Place the adapter cap over the aerobic bottle and press straight down to pierce
the septum. Hold the bottle upright, below the level of the draw site, and add up to
10 ml of blood per adult bottle and up to 4 ml per pediatric bottle.** Ensure the
bottle is correctly filled to the Fill-to Mark or target fill level. Once the aerobic bottle
has been inoculated, repeat the procedure for the anaerobic bottle.
6 OTHER BLOOD TESTS
If blood is being collected for other tests, an insert placed into the adapter cap
may be required. The insert is used to guide blood collection tubes onto
the needle.
If other blood tests are requested, always collect the blood culture first.
7 FINISH THE PROCEDURE
Discard the winged collection set into a sharps container and cover the
puncture site with an appropriate dressing. Remove gloves and wash hands
before recording the procedure, including indication for culture, date, time,
site of venipuncture, and any complications.
Ensure additional labels are placed in the space provided on the bottle
label and do not cover the bottle barcodes, and that the tear-off barcode
labels are not removed. If additional labels contain a barcode, they should be
positioned in the same manner as the bottle barcode.
Inoculated bottles should be transported to the laboratory for testing as
quickly as possible, preferably within 2 hours per CLSI.
(3) If delays are expected,
it is important to refer to the manufacturer’s Instructions for Use for guidance.
* The use of blood collection sets without blood collection adapters is not recommended.
**Avoid holding the blood culture bottle in a horizontal or upside down position or drawing blood with a
needle connected directly to the adaptor cap, as fill level cannot be monitored during collection and there
is a possible risk of media reflux into the bloodstream.
These recommendations illustrate the best practices for blood culture collection based on the
World Health Organization recommendations (WHO guidelines on drawing blood: best practices in
phlebotomy. 2010. ISBN 978 92 4 159922 1). Best practices may vary between healthcare facilities;
refer to guidelines applicable in your facility.
1 PREPARE BLOOD COLLECTION KIT
Confirm the patient’s identity and gather all required materials before beginning the collection process.
Do not use blood culture bottles beyond their expiration date, or bottles
which show signs of damage, deterioration or
contamination.
It is recommended to identify the Fill-to Mark or
mark the target fill level on the blood culture
bottle label about 10 ml above the media level.
2 PREPARE BOTTLES FOR INOCULATION
Wash hands with soap and water then dry, or apply an alcohol hand rub or
another recognized effective hand rub solution.
Remove the plastic “flip-cap” from the blood culture bottles and disinfect the
septum using an appropriate and recognized effective disinfectant, such as
chlorhexidine in 70% isopropyl alcohol, 70% isopropyl alcohol, or tincture of
iodine in swab or applicator form. Use a fresh swab/applicator for each bottle.
Allow bottle tops to dry in
order to fully disinfect.
Conventional needles and syringes should be replaced
wherever possible with winged blood collection sets,
which are safer.(59, 60, 61)
They should only be used if prevention measures to
Accidental Blood Exposure are strictly applied*
. Needles
must not be recapped, purposely bent or broken by hand,
removed from disposable syringes or otherwise
manipulated by hand.
2 PREPARE BOTTLES FOR INOCULATION
Wash hands with soap and water then dry, or apply an alcohol hand rub or
another recognized effective hand rub solution.
Remove the plastic “flip-cap” from the blood culture bottles and disinfect the
septum using an appropriate and recognized effective disinfectant, such as
chlorhexidine in 70% isopropyl alcohol, 70% isopropyl alcohol, or tincture of
iodine in swab or applicator form. Use a fresh swab/applicator for each bottle.
Allow bottle tops to dry in order to fully disinfect.
3 PREPARE VENIPUNCTURE SITE
If skin is visibly soiled, clean with soap and water. Apply a disposable tourniquet
and palpate for a vein. Apply clean examination gloves (sterile gloves are not
necessary).
Cleanse the skin using an appropriate disinfectant, such as chlorhexidine in 70%
isopropyl alcohol or tincture of iodine in swab or applicator form. The venipuncture
site is not fully clean until the disinfectant has fully evaporated.
4 VENIPUNCTURE
Attach the needle to a syringe. To prevent contaminating the puncture site,
do not re-palpate the prepared vein before inserting the needle.
Insert the needle into the
prepared vein.
5 CULTURE BOTTLE INOCULATION
Collect the sample. Transfer the blood into the culture bottles, starting with
the anaerobic bottle. Hold the bottle upright, and add up to 10 ml of blood per
adult bottle and up to 4 ml per pediatric bottle. Ensure the bottle is correctly
filled to the Fill-to Mark or target fill level. Once the anaerobic bottle has been
inoculated, repeat the procedure for the aerobic bottle.
6 FINISH THE PROCEDURE
Discard the needle and syringe into a sharps container and cover the puncture
site with an appropriate dressing. Remove gloves and wash hands before
recording the procedure, including indication for culture, date, time, site of
venipuncture, and any complications.
Ensure additional labels are placed in the space provided on the bottle
label and do not cover the bottle barcodes, and that the tear-off barcode
labels are not removed. If additional labels contain a barcode, they should be
positioned in the same manner as the bottle barcode. Inoculated bottles
should be transported to the laboratory for testing as quickly as possible,
preferably within 2 hours per CLSI. (3) If delays are expected, it is important to
refer to the manufacturer’s Instructions for Use for guidance.
* Refer to recognized guidelines such as those issued by the WHO or CDC:
http://www.who.int/injection_safety/phleb_final_screen_ready.pdf
http://www.cdc.gov/niosh/docs/2000-108/pdfs/2000-108.pdf
These recommendations illustrate the best practices for blood culture collection based on the
World Health Organization recommendations (WHO guidelines on drawing blood: best practices in
phlebotomy. 2010. ISBN 978 92 4 159922 1). Best practices may vary between healthcare facilities;
refer to guidelines applicable in your facility
