title: Consensus sequence-based scheme for epidemiological typing of clinical and environmental isolates of Legionella pneumophila.
abstract: A previously described sequence-based epidemiological typing method for clinical and environmental isolates of Legionella pneumophila serogroup 1 was extended by the investigation of three additional gene targets and modification of one of the previous targets. Excellent typeability, reproducibility, and epidemiological concordance were determined for isolates belonging to both serogroup 1 and the other serogroups investigated. Gene fragments were amplified from genomic DNA, and PCR amplicons were sequenced by using forward and reverse primers. Consensus sequences are entered into an online database, which allows the assignment of individual allele numbers. The resulting sequence-based type or allelic profile comprises a string of the individual allele numbers separated by commas, e.g., 1,4,3,1,1,1, in a predetermined order, i.e., flaA, pilE, asd, mip, mompS, and proA. The index of discrimination (D) obtained with these six loci was calculated following analysis of a panel of 79 unrelated clinical isolates. A D value of > 0.94 was obtained, and this value appears to be sufficient for use in the epidemiological investigation of outbreaks caused by L. pneumophila. The D value rose to 0.98 when the results of the analysis were combined with those of monoclonal antibody subgrouping. Sequence-based typing of L. pneumophila is epidemiologically concordant and discriminatory, and the data are easily transportable. This consensus method will assist in the epidemiological investigation of L. pneumophila infections, especially travel-associated cases, by which it will allow a rapid comparison of isolates obtained in more than one country.
authors.affiliation: Istituto Cantonale di Microbiologia, Bellinzona, Switherland.
authors.forename: Valeria
authors.initials: V
authors.lastname: Gaia
authors.forename: Norman K
authors.initials: NK
authors.lastname: Fry
authors.forename: Baharak
authors.initials: B
authors.lastname: Afshar
authors.forename: P Christian
authors.initials: PC
authors.lastname: Lück
authors.forename: Hélène
authors.initials: H
authors.lastname: Meugnier
authors.forename: Jerome
authors.initials: J
authors.lastname: Etienne
authors.forename: Raffaele
authors.initials: R
authors.lastname: Peduzzi
authors.forename: Timothy G
authors.initials: TG
authors.lastname: Harrison
mesh_terms: D015373:Bacterial Typing Techniques; D001483:Base Sequence; D016384:Consensus Sequence; D017931:DNA Primers; D004269:DNA, Bacterial / Q000235:genetics; D020869:Gene Expression Profiling; D006801:Humans; D016952:Legionella pneumophila / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D007877:Legionnaires' Disease / Q000453:epidemiology; D016133:Polymerase Chain Reaction; D015203:Reproducibility of Results; D012703:Serotyping / Q000379:methods
chemical_list: D017931:DNA Primers; D004269:DNA, Bacterial