A sputum culture test is one of the tests used to check for a lung infection and to see what organisms are causing an infection. A sample of phlegm coughed up from deep within the lung is sent to the lab. The lab will grow the bacteria or fungus causing the infection.
The sputum culture test helps your healthcare provider make a definite diagnosis and determine the best treatment.
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. Do not stop any of your regular medicines without first talking to your provider about it.
There are several ways to obtain 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 phlegm into the cup. It is important that you cough up a sample from deep down in your lung. The saliva from inside your mouth will not be helpful. You may be given a breathing treatment (an inhaled mist that stimulates coughing) to help you bring up a sample. Keep the lid on the sample container until you are ready to spit the sample into the cup. 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 sample of phlegm for culturing. For a bronchoscopy, your provider uses a thin, flexible, lighted tube to look at the airway in your lung and to get fluid and tissue samples. You will be given a sedative and local anesthetic before the procedure to keep you from gagging.
Ask your health care provider when and how you will get the result of your test. It usually takes 2 to 4 days for the sputum culture to grow most bacteria. However, if the test is looking for tuberculosis or fungus, it may be several days to weeks before you get final results.
A negative test result means no bacteria or fungus grew in the culture. A negative test result is considered a normal test result. Usually a positive test result means you have a lung infection (like bronchitis or pneumonia). However, the result could be positive when you do not have an infection if too many bacteria from your mouth are in the sample.
Test results are only one part of a larger picture that takes into account your medical history and current health. Sometimes a test needs to be repeated to check the first result. Talk to your healthcare provider about your result and ask questions. If your test result is not normal, ask your provider:
