Sputum is the name given to the mucus that is coughed up from the lower airways and expectorated via the mouth. It contains mucus, cellular debris, and microorganisms. It may also contain blood or pus. Sputum includes saliva, foreign material, and substances such as mucus or phlegm. Microbiological sputum samples are usually used to look for infections by Moraxella catarrhalis, Mycobacterium tuberculosis, Streptococcus pneumoniae and Haemophilus influenzae. Other pathogens can also be found. Yellow to green color of the sputum and/or blood indicate that the 'cold' is severe and the patient should be examined by a physician. who may need to prescribe antibiotics.