May 2023: Changes to Legionella Diagnostic Testing (LEGPCR)

Clinical Updates

Changes to Legionella Diagnostic Testing (LEGPCR)

Effective May 2, 2023.

Improvements to Cleveland Clinic Laboratories’ Legionella PCR assay will result in the discontinuation of most Legionella cultures.

Beginning May 2, 2023, Legionella pneumophila PCR (LEGPCR) will include additional DNA targets for Legionella, including species other than Legionella pneumophila, and a target specific for Legionella pneumophila serogroup 1.

This assay design is modeled after the U.S. Centers for Disease Control & Prevention’s assay.1

Legionella pneumophila PCR (LEGPCR)

Specimen Requirements
Lower respiratory samples, including bronchoalveolar lavage (BAL) and sputa, will continue to be the acceptable specimen types for PCR.

Possible interpretations of test results include:

  • Legionella pneumophila Serogroup 1 Detected
  • Legionella pneumophila (not Serogroup 1) Detected
  • Legionella species (not pneumophila) Detected

Additional Updates
Beginning May 23, 2023, routine culture for Legionella spp. (LEGCUL) will be discontinued, but culture will reflexively be performed on any sample with detectable Legionella DNA by PCR.

Note: There is no change to Legionella urine antigen (LEGUAG) testing.


1 Benitez AJ, Winchell JM. Clinical application of a multiplex real-time PCR assay for simultaneous detection of Legionella species, Legionella pneumophila, and Legionella pneumophila serogroup 1. J Clin Microbiol. 2013 Jan;51(1):348-51. doi: 10.1128/JCM.02510-12.