A blood culture test helps your doctor figure out if you have a kind of infection that is in your bloodstream and can affect your entire body. Doctors call this a systemic infection. The test checks a sample of your blood for bacteria or yeast that might be causing the infection.

Why Would I Need One?

If your doctor orders this test, it’s because they think you might have a systemic infection and they want to check for certain kinds of germs in your blood. It can help them come up with the best treatment for you.

Your doctor might order the test if you have symptoms that may include:

• Fever or chills
• Fatigue
• Peeing less often than normal
• Nausea
• Confusion
• Faster heart rate or breathing

• Inflammation in different areas of your body
• Small blood clots forming in your small blood vessels
• A serious drop in your blood pressure
• Organ failure

What Happens During the Test?

A nurse or a phlebotomist (a medical technician who takes blood) will clean your skin and insert a thin needle into your vein to draw your blood. The process will be repeated using another vein to get the most accurate results.

In a lab, your blood samples will get mixed with a special material called a culture. It helps bacteria or yeast grow if they are already in your blood.

You may be able to get early results within 24 hours of your blood tests. But you might need to wait 48 to 72 hours to learn what kind of yeast or bacteria is causing your infection. You might need other tests, too.

You may be able to get early results within 24 hours of your blood tests. But you might need to wait 48 to 72 hours to learn what kind of yeast or bacteria is causing your infection. You might need other tests, too.

What Do the Results Mean?

Your doctor may talk about “positive” and “negative” results. If you get a “positive” result on your blood culture test, it usually means there are bacteria or yeast in your blood. “Negative” means there’s no sign of them.

If two or more of your blood cultures come back positive for the same type of bacteria or fungi, it’s likely that that’s the type of bacteria or yeast that’s causing your infection. An infection in your blood is serious. You’ll need immediate treatment, probably in a hospital.