MedlinePlus Medical Encyclopedia: Sputum DFA (direct fluorescent antibody)

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Sputum DFA (direct fluorescent antibody)

Contents of this page:
Alternative names Definition How the test is performed How to prepare for the test How the test will feel	Why the test is performed Normal Values What abnormal results mean What the risks are

Alternative names

Direct immunofluoresence test

Definition Return to top

This is a test performed to detect the presence of microorganisms in sputum by using antibodies tagged with a fluorescent dye.

How the test is performed Return to top

A sputum sample is obtained by coughing into a specimen container. In the laboratory, antibodies that have been chemically linked to a fluorescent dye are added to the sample. The "flagged" antibodies will attach themselves to the specific antigens (in this case, the microorganism against which they were formed). The specific microorganism (antigen) is indirectly identified by the presence of fluorescence when examined under a special microscope.

How to prepare for the test Return to top

Obtain a coughed sputum specimen. If there is not a productive cough, a respiratory treatment may produce a sample.

How the test will feel Return to top

There is no discomfort.

Why the test is performed Return to top

This test may be performed when certain types of pulmonary infections or pneumonias are suspected.

Normal Values Return to top

Normally, there is no antigen-antibody reaction. A reaction indicates infection.

What abnormal results mean Return to top

Abnormal results may indicate a specific infection depending on the antigens tested. Legionella or Mycoplasma pneumonia are 2 infections that can be determined by this test.

What the risks are Return to top

There are no risks.

Update Date: 9/3/2003

Updated by: Michael C. Milone, M.D., Ph.D., Department of Pathology and Laboratory Medicine, University of Pennsylvania Medical Center, Philadelphia, PA. Review provided by VeriMed Healthcare Network.

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