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Blood normally doesn't have any bacteria or fungi in it. A blood culture is a test of a blood sample to find germs (such as bacteria or a fungus) that can cause an infection.
A bacterial infection in the blood, called bacteremia, can be serious. That's because the blood can spread the bacteria to any part of the body. A blood infection most often occurs with other serious infections, such as those affecting the lungs, kidneys, bowel, gallbladder, Opens dialog, or heart valves.
A blood infection may also develop when the immune system, Opens dialog is weak. This can occur in infants and older adults. It can happen because of a disease (such as cancer or AIDS) or from medicines (such as corticosteroids or chemotherapy) that change how well your body can fight infections (immunity).
For a blood culture, a sample of blood is added to a substance that promotes the growth of germs. The type of germ may be found using a microscope or chemical tests. Sometimes other tests are done to find the right medicine for treating the infection. This is called sensitivity testing. Two or three blood samples from different veins are often taken to make sure that a bacteria or fungus is not missed.
Find a bacterial infection that has spread into the blood, such as meningitis, osteomyelitis, pneumonia, a kidney infection, or sepsis. A culture can also show what type of bacteria is causing the infection.
Find a fungal infection, such as yeast, in the blood.
Find the best medicines to kill the bacteria or fungi. This is called sensitivity testing.
Find the cause of an unexplained fever or shock or a person becoming extremely ill.
A health professional uses a needle to take a blood sample, usually from the arm. Blood may be taken from two or three places on your body. Or it may be taken at two different times a few hours apart.
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Information about Blood Culture
When a blood sample is taken, you may feel nothing at all from the needle. Or you might feel a quick sting or pinch.
There is very little chance of having a problem from this test. When a blood sample is taken, a small bruise may form at the site.
Most bacteria can be seen in the culture in 2 to 3 days. But some types can take 10 days or longer to show up. Fungus can take up to 30 days to show up in the culture.
Normal:
No bacteria or fungus is found. Normal culture results are called negative.
Abnormal:
Bacteria or fungus grows in the culture. Abnormal culture results are called positive.
If bacteria are found in the culture, another test is often done to find the best antibiotic that will kill the bacteria. This is called sensitivity or susceptibility testing. Sensitivity testing is important so the blood infection is treated correctly. This also helps prevent bacteria from becoming resistant to antibiotics.
Author: Ignite Healthwise, LLC Staff Clinical Review Board All Healthwise education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.
This information does not replace the advice of a doctor. Ignite Healthwise, LLC, disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. Learn how we develop our content.
