Screening-level assays for potentially human-infectious environmental Legionella spp

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From: The Journal of Microbiology(Vol. 49, Issue 2)
Publisher: Springer
Document Type: Report
Length: 310 words

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Byline: Helen Y. Buse (1), Abby Brehm (1), Jorge W. Santo Domingo (2), Nicholas J. Ashbolt (1) Keywords: Legionella spp.; Acanthamoeba polyphaga; biofilms; virulence; macrophages Abstract: In spite of the fact that various Legionella species are isolated from nonclinical water settings, there is no standard method to determine whether environmental legionellae may be infectious to humans. Here we provide a screening-level approach based on an in vivo murine (A/J mouse) model and three in vitro proliferation assays using Acanthamoeba polyphaga, and THP-1 human and J774 murine macrophage cell lines to identify potentially human-infectious legionellae. As an initial demonstration the infectivity potential of three clinical (Legionella pneumophila, L, longbeacheae, and L. micdadei) and three environmental (L. dumoffii, L. maceachernii, and L. sainthelensi) legionellae were evaluated. A/J mice were intranasally infected and by 6 h post infection (p.L), there were significant bacterial titers in the lungs. L. pneumophila, L. dumoffii, and L. micdadei densities were higher than L. longbeacheae, L. maceacherni, and L. sainthelensi at 24 h p.i. However, only L. pneumophila and L. micdadei persisted in the lungs after 48 h, indicating that the other isolates were rapidly cleared. Results from the in vitro assays showed that only L. pneumophila significantly multiplied within A. polyphaga, THP-1 and J774 cells after 72 h, but lysis of any of the in vitro hosts also flagged the strains for potential concern (e.g. L. dumoffii and L. micdadei). The results demonstrate the value of using multiple approaches to assess the potential level of pathogenicity of Legionella strains isolated from different environmental matrices. Author Affiliation: (1) National Exposure Research Laboratory, Office of Research and Development, US Environmental Protection Agency, Cincinnati, OH, 45268, USA (2) National Risk Management Research Laboratory, Office of Research and Development, US Environmental Protection Agency, Cincinnati, OH, 45268, USA Article History: Registration Date: 29/04/2011 Received Date: 29/06/2010 Accepted Date: 08/12/2010 Online Date: 03/05/2011

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Gale Document Number: GALE|A266640492