Blood cultures should be drawn prior to initiation of antimicrobial therapy.
Preparation of skin prior to blood culture collection is important to prevent contamination of
sample.
At least two (2) sets of blood cultures should be obtained (each set includes one (1) aerobic and
one (1) anaerobic bottle).
Each set of blood cultures are to be drawn from two separate venipuncture sites at approximately
15 minutes apart.
If two separate venipunctures are not able to be drawn, the provider must be notified, and
collaboration should be done to determine if two sets are necessary.
Central lines (includes dialysis lines and Mediports) and Peripherally Inserted Central Catheters
(PICCs) should not be used to obtain blood cultures due to the high probability of colonization
and the likelihood of false positive results.
Central lines from outside facilities may be cultured for up to two (2) calendar days (as opposed to
48 hours), after admission by provider order only for a positive blood culture to be considered
present on admission.
Blood culture volume is essential. There is a 3% increase in sensitivity for every extra mL
collected. Blood culture bottles require 8- 10 mLs. to be accurate.
After positive blood cultures have been identified wait at least 48 hours to draw any additional
blood cultures.
Surveillance blood cultures should not be routinely done.
Neutropenic (ANC < 1500 µL) or thrombocytopenic (Platelets < 30,000 µL) patients suspected of
having a blood stream infection are to have peripheral blood culture attempted twice before
considering drawing a blood culture from a central line or PICC. It is imperative that cultures in
these patients are drawn within an hour of suspected infection has been identified.
Fill aerobic bottle first then anaerobic bottles
These bottles contain a culture medium designed to support the growth of aerobic (oxygen-
requiring) organisms. If the aerobic bottle is filled first, the blood is immediately mixed with
the aerobic medium, which can help maintain the viability of aerobic organisms.
Anaerobic Bottles: These bottles are designed to support the growth of anaerobic (oxygen-
sensitive) organisms. If the anaerobic bottle is filled first, any residual air or oxygen in the
syringe could be introduced into the bottle, potentially inhibiting the growth of anaerobic
organisms.
Drawing the aerobic culture first minimizes the risk of introducing contaminants from
the syringe into the anaerobic bottle, as any minor contamination is less likely to
affect aerobic cultures.
Number and Timing of Blood Cultures
Condition Recommendations
Suspected acute primary Obtain 2 sets at the same time by separate venipuncture immediately
bacteremia or fungemia, following the clinical events that precipitate the blood culture.
meningitis, osteomyelitis,
arthritis, or pneumonia
Obtain 2 to 3 blood culture sets initially at the same time by separate
venipuncture. Then, 24 to 36 hours later, obtain two more sets of cultures
Fever of unknown origin
immediately before the expected (usually afternoon) temperature
elevation.
Suspected bacteremia or Consider alternative blood culture methods designed to recover rare or
fungemia with persistently fastidious microorganisms (e.g. Isolator tube)
negative blood cultures
Infective endocarditis Obtain 4 blood culture sets during the first 1-2 hours of evaluation. If all are
negative 24 hours later, obtain 4 more sets. From patients who have
received antimicrobial agents within 2 weeks prior to admission, obtain two
separate blood cultures on each of three successive days. Request extended
incubation if Brucella or Bartonella is suspected.
Bacterial Example Oxygen Blood Type of Bottle
Classification Bacteria Requirement Collection
Method
Obligate Mycobacterium Require oxygen Collect blood Aerobic blood
Aerobes tuberculosis aseptically. Use culture bottles
aerobic bottles. (e.g., BD
Transport BACTEC Plus
promptly. Aerobic/F)
Obligate Clostridium Oxygen is toxic Collect blood Anaerobic
Anaerobes perfringens aseptically. blood culture
Minimize air bottles (e.g.,
exposure. Use BD BACTEC
anaerobic Lytic/10
bottles. Anaerobic/F)
Facultative Escherichia coli Prefer oxygen Collect blood Aerobic and
Anaerobes but can live aseptically. Use Anaerobic
without it both aerobic blood culture
and anaerobic bottles (e.g.,
bottles. BD BACTEC
Transport Plus Aerobic/F
promptly. and Lytic/10
Anaerobic/F)
Microaerophile Helicobacter Require low Collect blood Microaerophilic
s pylori oxygen levels aseptically. blood culture
Maintain low bottles (e.g.,
oxygen levels. Oxoid
Use specialized Microaerobic)
microaerophilic
bottles.
Aerotolerant Lactobacillus Do not require Collect blood Anaerobic
Anaerobes spp. oxygen but are aseptically. Use blood culture
not harmed by anaerobic bottles (e.g.,
it bottles. Can BD BACTEC
also use Lytic/10
aerobic bottles. Anaerobic/F)
Transport
promptly.
