Sputum. Scanning electron micrograph (SEM) of a bacterial culture from sputum. Phlegm is a secretion in the airway during disease and inflammation. Phlegm usually contains mucus with virus, bacteria, other debris, and sloughed-off inflammatory cells. Sputum is mucus and is the name used for the coughed-up material (phlegm) from the lower airways (trachea and bronchi). In medicine, sputum samples are usually used for naked eye exam, microbiological investigations of respiratory infections and cytological investigations of respiratory systems. Microbiological sputum samples are used to look for infections, such as Moraxella catarrhalis, Mycobacterium tuberculosis, Streptococcus pneumoniae, and Haemophilus influenzae. Other pathogens can also be found. Magnification: x1500 when printed at 10cm