Definition: A gram stain is a method of identifying bacteria. A cotton swab is usually used to take a sample of infected fluid. This fluid is applied to a glass slide which is then stained with a violet stain, followed by an iodine solution. Next, a decolorizer such as alcohol or acetone is applied to the slide. Finally the slide is counterstained with safranin. Some bacteria retain the purple violet stain and others retain the pink safranin stain. The difference in the color of a bacteria after a gram stain is a primary tool used to identify and classify the bacteria.
Also Known As: Gram's stain, Gram's method
Common Misspellings: gramstain
