Understanding Your Medical Test: What It Is, How It Is Done, and What to Expect
A laboratory test that grows and identifies bacteria from a blood sample to detect infections.
{"This test helps doctors find out if you have a bacterial infection","A small blood sample is taken and sent to a lab to grow bacteria","Results usually take 2-5 days to complete","Finding the specific bacteria helps doctors choose the right antibiotic","If no bacteria grow, it may mean you don't have a bacterial infection"}
Key facts at a glance
- LOINC
- 44844-9
- Short code
- CULTID4
- Synonyms
- Bacteria Spec Cult org #4
- Category
- chemistry
- Sample
- serum
- Container
- Sterile, leak-proof container appropriate to specimen type (e.g., blood culture bottles, sterile screw-cap tube, culture swab with transport medium, sterile cup for urine)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 0 years
- Method
- culture
- CPT
- 87077
- SNOMED
- 441902008
- Specimen volume
- Variable by specimen type: 1-10 mL for fluids, 8-10 mL per blood culture bottle (aerobic and anaerobic sets), swabs submitted with adequate sample on transport medium
- Stability
- Transport to laboratory as soon as possible. Most specimens should be processed within 2 hours at room temperature; if delayed, refrigerate (2-8°C) except for blood cultures, CSF, and certain fastidious organisms. Specific stability depends on specimen type
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 24–72 hours
- Order
- routine
This test helps your healthcare provider check how your body is working and look for signs of illness or injury. The results give your care team important information they can use to confirm or rule out a diagnosis, guide treatment decisions, and monitor your health over time.
A bacterial culture test is a laboratory procedure used to detect and identify bacteria in your blood. Your blood is normally sterile, meaning it should not contain any bacteria. If bacteria are found in your blood, it may indicate a serious infection called bacteremia or sepsis. This test helps doctors determine the exact type of bacteria causing your infection, which is essential for prescribing the most effective treatment.
Your test will be performed by a trained member of your healthcare team, such as a doctor, nurse, or laboratory technician. The exact steps depend on the type of test, but most involve collecting a small sample, such as blood or urine, or taking measurements or images with special equipment.
A healthcare professional will clean the skin on your arm with an antiseptic and draw a small sample of blood into a sterile bottle containing special nutrients that help bacteria grow. This sample is then sent to a laboratory where it is placed in an incubator at body temperature. Laboratory technicians observe the sample over several days to see if bacteria multiply. If bacteria grow, they are identified using various techniques and tested against different antibiotics to determine which ones will be most effective.
Most tests are quick and cause little to no discomfort. You may feel a brief pinch or sting if a sample is collected, and some tests require you to hold still for a short time. Afterward, you can usually return to your normal activities right away, and your provider will explain when and how you will get your results.
The blood draw may cause slight discomfort or bruising at the puncture site. Results typically take 2 to 5 days because bacteria need time to grow in the laboratory. If bacteria are identified, the lab will provide a report specifying the type of bacteria and which antibiotics can treat the infection. In some cases, additional testing may be needed to confirm the results or determine the best treatment approach.
Reference range
No growth of pathogenic bacteria; normal flora may be reported as such depending on specimen sourceN/A
No special patient preparation required. Specimen should be collected prior to initiation of antibiotic therapy whenever possible. Follow site-specific collection guidelines (e.g., clean-catch midstream for urine, sterile technique for blood, tissue, or fluid specimens)
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
A positive bacterial culture indicates that bacteria are present in your bloodstream, which typically means you have a bacterial infection requiring treatment. This test is crucial for diagnosing serious conditions such as sepsis, endocarditis (heart valve infection), or infections that have spread from other parts of the body. Identifying the specific bacteria allows doctors to select targeted antibiotics rather than using broad-spectrum medications, which helps combat antibiotic resistance and ensures more effective treatment. A negative result (no bacteria growth) after the observation period suggests your symptoms may be caused by a viral infection, a different type of microorganism, or a non-infectious condition.
Frequently asked questions
Why do I need this test?
How long will it take to get results?
What does it mean if bacteria are found?
What does a negative result mean?
Do I need to fast before this test?
Sources
- 1
- 2
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy