title: Whole-Genome Mapping as a Novel High-Resolution Typing Tool for Legionella pneumophila.
abstract: Legionella is the causative agent for Legionnaires' disease (LD) and is responsible for several large outbreaks in the world. More than 90% of LD cases are caused by Legionella pneumophila, and studies on the origin and transmission routes of this pathogen rely on adequate molecular characterization of isolates. Current typing of L. pneumophila mainly depends on sequence-based typing (SBT). However, studies have shown that in some outbreak situations, SBT does not have sufficient discriminatory power to distinguish between related and nonrelated L. pneumophila isolates. In this study, we used a novel high-resolution typing technique, called whole-genome mapping (WGM), to differentiate between epidemiologically related and nonrelated L. pneumophila isolates. Assessment of the method by various validation experiments showed highly reproducible results, and WGM was able to confirm two well-documented Dutch L. pneumophila outbreaks. Comparison of whole-genome maps of the two outbreaks together with WGMs of epidemiologically nonrelated L. pneumophila isolates showed major differences between the maps, and WGM yielded a higher discriminatory power than SBT. In conclusion, WGM can be a valuable alternative to perform outbreak investigations of L. pneumophila in real time since the turnaround time from culture to comparison of the L. pneumophila maps is less than 24 h.
authors.affiliation: National Institute for Public Health and the Environment, Bilthoven, the Netherlands thijs.bosch@rivm.nl.
authors.forename: Thijs
authors.initials: T
authors.lastname: Bosch
authors.affiliation: Regional Public Health Laboratory Kennemerland, Haarlem, the Netherlands.
authors.forename: Sjoerd M
authors.initials: SM
authors.lastname: Euser
authors.affiliation: National Institute for Public Health and the Environment, Bilthoven, the Netherlands.
authors.forename: Fabian
authors.initials: F
authors.lastname: Landman
authors.affiliation: Regional Public Health Laboratory Kennemerland, Haarlem, the Netherlands.
authors.forename: Jacob P
authors.initials: JP
authors.lastname: Bruin
authors.affiliation: Regional Public Health Laboratory Kennemerland, Haarlem, the Netherlands.
authors.forename: Ed P
authors.initials: EP
authors.lastname: IJzerman
authors.affiliation: Regional Public Health Laboratory Kennemerland, Haarlem, the Netherlands.
authors.forename: Jeroen W
authors.initials: JW
authors.lastname: den Boer
authors.affiliation: National Institute for Public Health and the Environment, Bilthoven, the Netherlands.
authors.forename: Leo M
authors.initials: LM
authors.lastname: Schouls
mesh_terms: D002874:Chromosome Mapping / Q000379:methods*; D004196:Disease Outbreaks; D005838:Genotype; D006801:Humans; D016952:Legionella pneumophila / Q000145:classification* / Q000235:genetics*; D007877:Legionnaires' Disease / Q000453:epidemiology / Q000382:microbiology*; D017720:Molecular Epidemiology / Q000379:methods; D058889:Molecular Typing / Q000379:methods*; D009426:Netherlands / Q000453:epidemiology; D015203:Reproducibility of Results; D013997:Time Factors