Screening-Level Assays for Potentially Human-Infectious Environmental Legionella spp

• Published in: The journal of microbiology Vol. 49; no. 2; pp. 200 - 207
• Main Authors: Buse, Helen Y., US Environmental Protection Agency, Cincinnati, OH, USA, Brehm, Abby, US Environmental Protection Agency, Cincinnati, OH, USA, Santo Domingo, Jorge W., US Environmental Protection Agency, Cincinnati, OH, USA, Ashbolt, Nicholas J., US Environmental Protection Agency, Cincinnati, OH, USA
• Format: Journal Article
• Language: English
• Published: Heidelberg The Microbiological Society of Korea 01.04.2011; Springer Nature B.V; 한국미생물학회
• Subjects: Acanthamoeba polyphaga; Aerosols; Animals; Bacteriological Techniques - methods; Biofilms; Biomedical and Life Sciences; Cell Line; Disease Models, Animal; Disinfection & disinfectants; Drinking water; Environmental Microbiology; Humans; LEGIONELLA; Legionella - isolation & purification; Legionella - pathogenicity; Legionellosis - microbiology; Legionnaires disease; Life Sciences; MACROFAGOS; MACROPHAGE; MACROPHAGES; Macrophages - microbiology; Mass Screening - methods; Mice; Mice, Inbred A; Microbiology; PATHOGENICITY; Pathogens; PATOGENICIDAD; POUVOIR PATHOGENE; Protozoa; R&D; Research & development; Virulence; 생물학; United States > US; spp; macrophages; virulence; biofilms
• ISSN: 1225-8873; 1976-3794
• DOI: 10.1007/s12275-011-0233-z

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.i.), 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.