Molecular diagnosis of Legionella infections – clinical utility of front-line screening as part of a pneumonia diagnostic algorithm.

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Molecular diagnosis of Legionella infections - clinical utility of front-line screening as part of a pneumonia diagnostic algorithm.

J Infect. 2015 Nov 26;

Authors: Gadsby NJ, Helgason KO, Dickson EM, Mills JM, Lindsay DS, Edwards GF, Hanson MF, Templeton KE, ESCMID Study Group for Molecular Diagnostics and the ESCMID Study Group for Legionella Infections, Basel, Switzerland

Abstract
OBJECTIVES: Urinary antigen testing for Legionella pneumophila serogroup 1 is the leading rapid diagnostic test for Legionnaires' Disease (LD); however other Legionella species and serogroups can also cause LD. The aim was to determine the utility of front-line L. pneumophila and Legionella species PCR in a severe respiratory infection algorithm.
METHODS: L. pneumophila and Legionella species duplex real-time PCR was carried out on 1944 specimens from hospitalised patients over a 4 year period in Edinburgh, UK.
RESULTS: L. pneumophila was detected by PCR in 49 (2.7%) specimens from 36 patients. During a LD outbreak, combined L. pneumophila respiratory PCR and urinary antigen testing had optimal sensitivity and specificity (92.6% and 98.3% respectively) for the detection of confirmed cases. Legionella species was detected by PCR in 16 (0.9%) specimens from 10 patients. The 5 confirmed and 1 probable cases of L. longbeachae LD were both PCR and antibody positive.
CONCLUSIONS: Front-line L. pneumophila and Legionella species PCR is a valuable addition to urinary antigen testing as part of a well-defined algorithm. Cases of LD due to L. longbeachae might be considered laboratory-confirmed when there is a positive Legionella species PCR result and detection of L. longbeachae specific antibody response.

PMID: 26632328 [PubMed - as supplied by publisher]