Blood Culture Test

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KEY POINTS

• A blood culture checks for bacterial or fungal infection of the blood. Knowing what kind of bacteria or fungus is causing it can help your provider know what medicine is the best treatment.
• A small amount of blood is taken from a vein in your arm with a needle. The blood is collected in tubes and sent to a lab.
• Talk to your healthcare provider about what the test results mean and ask any questions you have.

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What is a blood culture test?

A blood culture is a test that checks for bacterial or fungal infection of the blood.

Why is it done?

An infection in the blood can be very serious. This test can help your healthcare provider know if your blood is infected and identify the type of bacteria or fungus causing the infection. Knowing what kind of bacteria or fungus is causing it can help your provider know what medicine is the best treatment.

Your provider may do this test if you have a fever with no clear cause or you are very sick.

How do I prepare for this test?

You may need to avoid taking certain medicines before the test because they might affect the test result. Make sure your healthcare provider knows about any medicines (especially antibiotics), herbs, or supplements that you are taking. Ask your provider before stopping any of your regular medicines.

How is the test done?

Having this test will take just a few minutes. A small amount of blood is taken from a vein in your arm with a needle. Blood may be taken from more than 1 site. The blood is collected in tubes and sent to a lab, where it is placed in a container with nutrient substances to see if any germs grow.

Most bacteria grow in a culture within 24 to 48 hours. Fungus may take as long as 30 days to show up. Ask your healthcare provider when and how you will get the result of your test.

What does the test result mean?

A test is negative if it does not find any bacteria or fungus in the blood sample. If your test is negative, you may be tested again to check the result.

A blood culture test is positive if bacteria or fungus grows in the culture. If your test is positive, different medicines will be tested in the lab to see which medicine will best treat the infection.

What if my test result is not normal?

Test results are only one part of a larger picture that takes into account your medical history, physical exam, and current health. Sometimes a test needs to be repeated to check the first result. Talk to your healthcare provider about your result and ask questions, such as:

• If you need more tests
• What kind of treatment you might need
• What lifestyle, diet, or other changes you might need to make