Testing sputum for lung diseases. Image 2 of 3. Researcher applying sputum (mucus coughed up from the lungs) from a patient to a petri dish. The patient may have one of many types of lung diseases, such as tuberculosis (TB), pneumonia or bronchitis, so their sample will be subjected to a number of different tests. Identifying the cause will enable the correct treatment to be given, such as antibiotics specific to the bacteria producing the disease. For example, TB is caused by Mycobacterium tuberculosis and is treated by 6-12 months of taking antibiotics. This is a much longer course than most, as this bacteria takes longer to be eliminated from the body than most others. See M874/711-M874/713 for a series of images showing sputum tests.