Sputum Culture
Reviewed
A sputum culture is a laboratory test that checks for bacteria or fungi that may be causing a respiratory tract infection in your lungs or airways. It helps diagnose infections such as pneumonia, tuberculosis, and bronchitis, and can monitor chronic lung conditions.
Preparation and collection
The test is often scheduled in the morning. You may be encouraged to drink more water the night before. You may be asked not to eat for 1–2 hours before the test. If you are having a bronchoscopy, you may need to fast for up to 12 hours. Tell your provider about all medicines you take, including antibiotics, but do not stop taking any medicine unless your provider tells you to.
Understanding this test
Use the reference interval and units printed by the laboratory that performed the test. A result outside that interval is not a diagnosis by itself, and a result inside it does not rule out every condition. Your symptoms, history, medicines, timing, and related tests can change what the result means.
- Antibiotics may affect bacterial growth and test results.
- Results may take a few days to weeks depending on the type of bacteria being tested.
- This test is not usually used for viral infections.
What to do next
Your healthcare provider will interpret your results based on your symptoms, medical history, and other tests. If your results are abnormal, additional tests may be needed to identify the specific infection.