Blood Culture

Alternate Name: Blood_Culture_SR CX


SAL Code:






Turn Around Time:

Preliminary reports start at 24 hours and continue through end of culture cycle.Final report 5-7 days.






Traditional culture setup; MICROSCAN Sensitivity and ID (where applicable); Gram stain (where applicable). If culture is positive, antibiotic susceptibilities (MICs) are only performed when appropriate. Feel free to call our microbiology department to discuss any special circumstances that may require additional workup.

Specimen Requirements:

Primary Tube:

Blood Culture Bottles

Primary Substance:




Stable Ambient:

48 hours

Stable Fridge:


Stable Frozen:


Rejection Criteria:

Improper samples, samples not labeled correctly, samples that are suspect for contamination.

Clinical Info:

To isolate and identify potentially pathogenic organisms causing bacteremia or septicemia. Additional blood cultures may be drawn to determine if bacteria present in the culture are persistent in the bloodstream (true pathogens). If they are not present in follow-up cultures, then bacteria from the skin or other sources may have contaminated the initial cultures. Additional blood cultures may also be drawn if the patient continues to have signs of sepsis but no microbe is recovered from the first cultures collected.

Additional Information:

The test request form must state clinical diagnosis. List current antibiotic therapy, clinical diagnosis, and any special organisms suspected or to rule out. Please indicate if the culture is for Brucella or Francisella.

Differentiating between a "true pathogenic isolate" and a contaminant is not a simple determination. Only a physician that is well versed in the clinical findings of microbiology testing of blood should make that determination. The number of positive cultures drawn by venipuncture is a very relevant criterion to use in determining whether an isolate is a contaminant.

In patients who have received antimicrobial drugs, four to six blood cultures may be necessary. Any organism isolated from the blood is usually tested for susceptibility. It is not recommended to culture blood while antimicrobials are present unless verification of an agent's efficacy is needed. This is confirmed with a single culture.

Sample Collection:

Use adult or pediatric blood culture collection kits provided by SAL. Blood cultures should be drawn prior to initiation of antimicrobial therapy. Strict aseptic technique is essential. If more than one culture is ordered, the specimens should be drawn separately at no less than 30 minutes apart to rule out the possibility of transient bacteremia due to self-manipulation by the patient of mucous membranes in the mouth caused by brushing teeth, etc, or by local irritations caused by scratching of the skin.

• Suspected sepsis, meningitis, osteomyelitis, arthritis, listeriosis, or acute untreated bacterial pneumonia: Obtain two blood cultures from two different sites, such as the left and right arms.

• Fever of unknown origin such as that caused by an occult abscess: Obtain two blood cultures initially. If those are negative, obtain two more 24 to 36 hours later. The yield beyond three or four cultures is virtually nil in this condition.

• Suspected early typhoid fever and brucellosis: Obtain four blood cultures during 24 to 36 hours due to low-grade bacteremia involved in these rarely seen diseases.

• Endocarditis (acute infective endocarditis): Obtain three blood cultures from three separate venipuncture sites during the first one to two hours and begin therapy.

Required volume:

16 to 20 mL total; 8 to 10 mL per aerobic and anaerobic bottle. Pediatric: up to 4 mL in one pediatric bottle; as age increases so should the volume of blood collected. Do not add more than 10 mL of blood to either the aerobic or anaerobic bottles, or more than 4 mL of blood to a pediatric bottle. The aerobic bottle has no minimum volume requirement. DO NOT VENT TUBES.

The major difficulty in interpretation of blood cultures is potential contamination by skin flora. This difficulty can be markedly reduced by careful attention to the details of skin preparation and antisepsis prior to collection of the specimen.

Skin preparation: First cleanse the venipuncture site with isopropanol. Then use an antiseptic swabstick or an antiseptic towelette to disinfect the site, using progressively larger concentric circles. This prepping agent should remain in contact with the skin for 30 seconds and be allowed to dry to ensure adequate disinfection. Allow antiseptic to air dry, DO NOT blow on the site. The venipuncture site must not be palpated after preparation.

Test Limitations:

Prior or current antibiotic therapy may cause negative cultures or delayed growth.

Test Handle Instructions:

Maintain at room temperatrure.

Test Information: