Sputum Culture Test

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KEY POINTS

• A sputum culture tests a sample of mucus coughed up from your lungs. It can help diagnose infections caused by bacteria or fungus.
• You will be asked to cough and spit some mucus into a sterile cup. The sample will then be sent to the 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 sputum culture test?

A sputum culture tests a sample of mucus coughed up from your lungs. The test checks for bacteria, viruses, or fungus in the mucus.

Why is this test done?

This test may be done to see what is causing an infection of your airways. It can help your healthcare provider know how to treat the infection.

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, herbs, or supplements that you are taking. Ask your provider before stopping any of your regular medicines.
• You may need to brush your teeth and rinse your mouth before the sample is collected. You may also need to avoid food for 1 or 2 hours before the test.
• Talk to your healthcare provider if you have any questions about the test.

How is the test done?

There are several ways to get a sputum sample. If you are able to cough up a sample, you will be given a sterile cup and asked to cough and spit some mucus into the cup. It’s important to take several deep breaths first and try to cough up a sample from deep in your lungs. The saliva from inside your mouth will not be helpful. You may be asked to breathe a mist that will make you start coughing. Keep the lid on the cup until you are ready to spit out the sample. Try not to touch the inside of the container. Put the lid back on the container as soon as you are done. The sample will then be sent to the lab.

A bronchoscopy is another way to get a mucus sample. For a bronchoscopy, your healthcare provider uses a flexible, lighted tube to look at the airways in your lungs and get fluid (mucus) and tissue samples. You will be given a numbing medicine to keep you from gagging and medicine to relax you before the procedure.

Ask your healthcare provider when and how you will get the result of your test.

What does the test result mean?

A negative test result means no bacteria or fungus grew in the culture. A negative test result is considered a normal test result.

A positive test result usually means you have a lung infection, like bronchitis or pneumonia. However, the result could be positive when you don’t have an infection if too many bacteria from your mouth are in the sample.

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 the results 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