Sputum is produced when a person’s lungs are diseased or damaged. Sputum is not saliva but the thick mucus – sometimes called phlegm – which is coughed up from the lungs.
here are many different reasons for the body to produce excess sputum. Below is a list of some of these causes, along with how the sputum may appear
Smoking In smokers, mucus builds up in the lungs, causing a “smoker’s cough.” The sputum produced may be green, yellow, or bloody.
Asthma: People with asthma have airways that are sensitive to allergens, environmental pollution, and respiratory infections. This sensitivity can lead to the airways becoming inflamed, as well as an increase in mucus production.
Cystic Fibrosis: Cystic fibrosis is an inherited disease caused by a defective gene. It leads to smaller airways becoming blocked by thick mucus, which causes breathing difficulties.
Respiratory tract infections (RTI): Sputum that is a different color from saliva may be a sign of a lower RTI. With bacterial RTIs, sputum may also have a thick consistency and an unpleasant odor. Some infections may cause sputum to be yellow, gray, or rusty colored. Some Common RTIs are Below
Flu : Flu, or influenza, may result in green phlegm. The main symptoms are:
high temperature, of 100.4°F or above
Bronchitis : Bronchitis is an infection of the lung’s main airways, the bronchi, which become inflamed and produce extra mucus. People with this condition may cough up yellow-grey or greenish sputum.
The sputum culture test is usually done with a gram stain, which identifies the bacteria that are causing the infection. If the gram stain is unable to detect the bacteria causing the infection, specialized tests may also be run. These include an AFB smear and culture to find tuberculosis and non-tuberculous mycobacteria infections, a fungal culture, or a Legionella culture.