What is a sputum culture?
Sputum (say "SPYOO-tum") is a thick fluid, or mucus, made in the lungs and in the airways leading to the lungs. A sputum culture tests a sample of sputum to see if it contains germs. The sputum is placed in a container with substances that help germs grow.
Why is a sputum culture done?
A sputum culture is done to:
- Find bacteria or fungi that are causing an infection of the lungs or the airways leading to the lungs. Examples include pneumonia and tuberculosis. Symptoms of a lung infection may include having a hard time breathing, pain when breathing, or a cough that produces bloody or greenish brown sputum.
- Find the best antibiotic to treat the infection. (This is called sensitivity testing.)
- See if treatment is working.
How is a sputum culture done?
- To give a sputum sample at home or your doctor's office, you will need to remove your dentures if you wear them. Rinse your mouth with water. Then take a deep breath and cough deeply to produce a sample of sputum.
- If you are having trouble coughing up a sample, you may be asked to inhale an aerosol mist to help you cough.
- You may need a bronchoscopy to collect a sputum sample. A thin, lighted tube (bronchoscope) will be inserted through your nose or mouth into the throat and then into the airways leading to the lungs. To collect the sample, a salt solution may be washed into the airway and then suctioned into a container.
How do you prepare for a sputum culture?
Do not use mouthwash before you collect your sputum sample. Some types of mouthwash can kill bacteria and could affect your results.
If bronchoscopy will be used to collect your sputum sample, your doctor will tell you how soon before the test to stop eating and drinking. Follow the instructions exactly about when to stop eating and drinking. If you don't, your surgery may be canceled. If your doctor told you to take your medicines on the day of surgery, take them with only a sip of water.
Tell your doctor if you have recently taken antibiotics.
What do the results of a sputum culture mean?
Some types of bacteria or fungi grow quickly in a culture. Others grow slowly. Test results may take from 1 day to several weeks. How long your results take depends on the type of infection your doctor thinks you may have. Some organisms don't grow in a standard culture and need a special growth medium to be found in a sputum culture.
Normal: | Sputum that has passed through the mouth normally contains several types of harmless bacteria. These include some types of strep (Streptococcus) and staph (Staphylococcus). The culture should not show any harmful bacteria or fungi. Normal culture results are negative. |
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Abnormal: | Harmful bacteria or fungi are found. The most common harmful bacteria in a sputum culture are those that can cause bronchitis, pneumonia, or tuberculosis. If harmful bacteria or fungi grow, the culture is positive. |
If test results point to an infection, sensitivity testing may be done. This testing helps to find the best antibiotic to kill the bacteria or fungus.
Even if your culture does not grow any bacteria or fungi, you may still have an infection.
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