What is the role of direct fluorescent antibody staining in the diagnosis of Legionella infection?

Updated: Nov 13, 2018
  • Author: Mobeen H Rathore, MD, CPE, FAAP, FIDSA; Chief Editor: Russell W Steele, MD  more...
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Direct fluorescent antibody staining for Legionella species

  • Direct fluorescent antibody (DFA) staining is a rapid test that can be performed on respiratory samples and tissue and requires only 2-4 hours for results.

  • DFA using a monoclonal antibody is highly specific.

  • A cross-reaction with Pseudomonas species rarely occurs, and patients with tularemia may have a false-positive DFA result for Legionella organisms.

  • DFA staining has a low sensitivity of 33-70%. [16] Sensitivity depends on the specimen quality, the number of organisms present, and the experience of the technician. A negative DFA result does not exclude Legionella infection.

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