Sputum

Sputum is mucus that is coughed up from the lower airways. It is usually used for microbiological investigations of respiratory infections.

The best sputum samples contain very little saliva, as this contaminates the sample with oral bacteria. This event is assessed by the clinical microbiologist by examining a Gram stain of the sputum. More than 25 squamous epithelial cells at low enlargement indicates salivary contamination.

When a sputum specimen is plated out, it is best to get the portion of the sample that most looks like pus onto the swab. If there is any blood in the sputum, this should also be on the swab.

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.

Purulent Sputum is that containing, or consisting of, pus.

Sputum can be:
 * 1) Bloody (often found in tuberculosis) (Hemoptysis)
 * 2) Rusty colored - usually caused by pneumococcal bacteria (in pneumonia)
 * 3) Purulent - containing pus. The color can provide hints as to effective treatment in Chronic Bronchitis Patients :
 * 4) a yellow-greenish (mucopurulent) color suggests that treatment with antibiotics can reduce symptoms. Green color is caused by Neutrophil Myeloperoxidase.
 * 5) a white, milky, or opaque (mucoid) appearance often means that antibiotics will be ineffective in treating symptoms. (This information may correlate with the presence of bacterial or viral infections, though current research does not support that generalization.)
 * 6) Foamy white - may come from obstruction or even edema.
 * 7) Frothy pink - pulmonary edema