What is the role of direct fluorescent antibody (DFA) testing in the evaluation for community-acquired pneumonia (CAP)?

Updated: Oct 31, 2019
  • Author: Stephanie L Baer, MD; Chief Editor: Michael Stuart Bronze, MD  more...
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Direct fluorescent antibody (DFA) testing of the sputum can be performed to try to assist with the diagnosis of atypical CAP pathogens, including Legionella, P jiroveci, and Chlamydophila; however, the utility of this test is hampered by suboptimal sensitivity and is relatively difficult to perform. A DFA stain showing Legionella infection is seen in the image below.

Sputum direct fluorescent antibody stain showing L Sputum direct fluorescent antibody stain showing Legionella infection.

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