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Blood Culture: About This Test

What is it?

A blood culture is done to check if bacteria or fungi are infecting your blood.

Usually, a blood infection occurs with other serious infections. These include infections in your lungs, kidneys, bowels, gallbladder, or heart valves.

You may also get a blood infection if your immune system is weak.

Why is this test done?

A blood culture is done to:

  • Find a bacterial infection that has spread into the blood. These include meningitis and osteomyelitis. They also include pneumonia, kidney infections, and sepsis.
  • Find a fungal infection in the blood. One common type is a yeast infection.
  • Check for endocarditis. This is a bacterial infection on the heart valves.
  • Find the best medicines to kill the bacteria or fungi.
  • Find the cause of an unexplained fever, shock, or other very serious illness.

How do you prepare for the test?

  • You do not need to do anything at home to prepare for the test.
  • Tell your health professional if you took antibiotics recently.

How is the test done?

A health professional takes a sample of your blood.

Blood cultures are taken in special bottles using a needle to draw blood from two separate veins (usually one from each arm).

What happens after the test?

  • If bacteria or yeast are found in the culture, your doctor may ask the lab to retest the blood several days later.
  • You will probably be able to go home right away.
  • You can go back to your usual activities right away.

Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor or nurse advice line (811 in most provinces and territories) if you are having problems. It's also a good idea to keep a list of the medicines you take. Ask your doctor when you can expect to have your test results.

Where can you learn more?

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