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Alternative names
Gram stain of stool; Feces Gram stainDefinition Return to top
Gram stain is a method of staining microorganisms (bacteria) using a special series of stains. In this test, a specimen of stool is stained and then examined under the microscope.
The Gram stain method can be applied to almost any clinical specimen and is one of the most commonly used techniques for the rapid diagnosis of bacterial infections.How the test is performed Return to top
A small amount of stool is applied in a very thin layer to a microscope slide. This is called a smear. A series of stains called a Gram stain is applied to the specimen. It is first stained with crystal violet stain, then iodine, then decolorized, then stained with safranin.
The stained smear is then examined under the microscope for the presence of bacteria. The color, size, and morphologic appearance (shape) of the cells help identify the infecting organism.
How to prepare for the test Return to top
Adults and children:How the test will feel Return to top
Some people feel discomfort or embarrassment with this test.Why the test is performed Return to top
The test may be performed to try to diagnose an infection or illness, sometimes involving diarrhea.Normal Values Return to top
The presence of only normal or "friendly" organisms is normal. All humans have bacteria in their intestines.What abnormal results mean Return to top
An intestinal infection may be present. Stool cultures and more sophisticated tests can also help diagnose the cause of the infection.What the risks are Return to top
There are no risks.Special considerations Return to top
Additional examinations of the specimen may be indicated for conditions other than infection. Update Date: 1/26/2004 Updated by: Daniel Levy, M.D., Ph.D., Infectious Diseases, Greater Baltimore Medical Center, Baltimore, MD. Review provided by VeriMed Healthcare Network.
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Page last updated: 28 October 2004 |