Definition of Gram stain of skin lesion:

A gram stain of a skin lesion is a laboratory test that uses special stains to detect and identify bacteria in a sample from a skin sore. The gram stain method is one of the most commonly used techniques for the rapid diagnosis of bacterial infections.

How the test is performed:

Your health care provider will remove a sample of tissue from the skin sore. For information on how this is done, see the article on skin lesion biopsy.

The sample is sent to a laboratory, where it is applied in a very thin layer to a glass slide. A series of different colored stains is applied to the sample. A laboratory team member examines the stained slide under a microscope, checking for bacteria. The color, size, and shape of the cells help identify the infecting organism.

How to prepare for the test:

No preparation is needed for the laboratory test.

How the test will feel:

The laboratory test is painless. For information on what it feels like to have the skin sample removed, see skin lesion biopsy.

Why the test is performed:

Your doctor may order this test if you have signs of an infected skin sore. The test is done to determine which bacteria is causing the infection.