What do the test results mean?

The results of this test usually take at least 48 hours. In some cases, up to six weeks may be needed to detect certain organisms. If a person gives a good sputum sample, it should not contain any organisms. Sometimes, a bad sample is taken, such as when a person simply spits into the cup. This sample may grow bacteria or other organisms, but does not give any useful information. This is because bacteria normally live in the throat and mouth. These bacteria do not usually cause an infection in the lungs.

If organisms are present in a good sputum sample, an infection is often present. The infection may be in the bronchi or deep in the lungs. Knowing the exact cause of an infection helps the healthcare provider advise a specific therapy. For example, if specific bacteria are found, the healthcare provider may want to give the person a specific antibiotic. In some cases, a person is given an antibiotic right away, before the test results are available. The healthcare provider may then switch the antibiotic if a specific organism is found.