Sputum is a type of thick mucus produced by the lungs and airways. It is also known as phlegm and is different from saliva or spit. Sputum contains cells from the immune system that help fight bacteria, fungi, or other foreign substances in the lungs or airways. The thickness of sputum helps trap foreign material, allowing tiny hairs in the airways called cilia to push it through the mouth and be coughed out. Sputum can be one of several different colors, and the colors can help identify the type of infection or if a chronic illness has become worse.

A sputum culture is a medical test that looks for bacteria or other germs to help diagnose an infection in the lungs or airways. It is a test that checks for bacteria or another type of organism that may be causing an infection in the lungs or the airways leading to the lungs. The test is done with a sputum sample from deep inside the lungs, and the sample is checked for bacteria or fungi causing the airways or lung infection. Healthcare providers perform sputum cultures to help find out if there’s an infection in the lungs or airways and what’s causing it. Providers use the test to diagnose, plan treatment, and monitor health conditions.

In summary, sputum is a type of thick mucus produced by the lungs and airways that contains cells from the immune system to fight foreign substances. A sputum culture is a medical test that checks for bacteria or another type of organism that may be causing an infection in the lungs or the airways leading to the lungs. Healthcare providers perform sputum cultures to help diagnose, plan treatment, and monitor health conditions.