Sputum gram stain

Alternative names:

gram stain of sputum

How the test is performed:

A sample of sputum is applied in a very thin layer to a microscope slide. The specimen is stained with a violet stain known as a gram stain and then examined under the microscope for the presence of bacteria. The color, number, and morphologic appearance of the cells make it possible to identify the genus of the organism.

How to prepare for the test:

Obtain a sputum sample from your lungs by coughing into a specimen container. If coughing does not produce sputum, a breathing treatment may precede the test to induce sputum production.

How the test will feel:

The person needing the test will usually have a productive cough. Occasionally, the sputum is collected by bronchoscopy, and more discomfort is associated with this procedure.

Why the test is performed:

The test is performed when there is a persistent or prolonged cough, sputum has a foul odor or unusual color, respiratory disease is suspected, or there is a generalized infection.