Blood Culture: About This Test

What is it?

A blood culture is a test to see what kind of 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?

• In general, there's nothing you have to do before this test, unless your doctor tells you to.
• Tell your health professional if you took antibiotics recently.

How is the test done?

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.

What happens after the test?

• If bacteria are found in the culture, the lab will likely test your blood again to find the best antibiotic to kill the bacteria.
• You will probably be able to go home right away.
• You can go back to your usual activities right away.