Gram stain of tissue biopsy test involves a gram stain (using crystal violet) of a sample of tissue taken from a biopsy.

The gram stain method can be applied to almost any clinical specimen and is an excellent technique for making a general, basic identification of the type of bacteria present in the sample.

A sample called a smear from a tissue specimen is usually applied in a very thin layer to a microscope slide. The specimen is stained with crystal violet stain and undergoes additional processing before it is examined under the microscope for the presence of microorganisms. Different characteristics such as color, shape and pattern of staining help determine the type of microorganism.

If the biopsy is included as part of a surgical procedure, food and fluid may need to be withheld overnight. If the biopsy is of a superficial tissue, food and fluid may need to be withheld for several hours before the procedure.

How the test feels depends on the part of the body being biopsied. There are several different methods for obtaining tissue samples. A needle may be inserted through the skin to the specific tissue. An incision through the skin into the tissue may be made with a small excision of the specific tissue. A biopsy may also be taken from inside the body by an instrument that visualizes the inside of the body, such as an endoscope or cystoscope. Some form of anesthetic is usually given. Pressure and occasional mild pain may be felt during a biopsy.

The test is performed when an infection of a body tissue is suspected.

The presence or type of organisms depends on the particular tissue being biopsied. Some tissues in the body are sterile, such as the brain, whereas other tissues normally contain organisms.

Abnormal results usually indicate an infection in the tissue site. Further tests are frequently needed to identify the specific type of organism involved.

Risks are only associated with obtaining a tissue biopsy and may include bleeding or infection.