title: Molecular epidemiology of Legionella pneumophila serogroup 1 isolates identify a prevalent sequence type, ST505, and a distinct clonal group of clinical isolates in Toyama Prefecture, Japan.
abstract: We performed comparative analyses of Legionella pneumophila serogroup (SG) 1 isolates obtained during 2005-2012 in Toyama Prefecture, Japan, by sequence-based typing (SBT) and pulsed-field gel electrophoresis (PFGE). Seventy-three isolates of L. pneumophila SG 1, including 17 isolates from patients, 51 from public baths, 4 from cooling towers, and 1 from a shower, were analyzed. The isolates were classified into 43 sequence types (STs) by SBT and 52 types by PFGE. Fourteen STs were unique to Toyama Prefecture, as determined from the SBT database of European Working Group for Legionella Infections (EWGLI), as of October 31, 2012. ST505 strain was identified in 4 isolates from patients and 5 isolates from public baths, and these isolates belonged to 2 PFGE types. These, however, were similar because of the difference with only two restriction fragments, indicating that ST505 strain was prevalent among L. pneumophila SG 1 isolates in this area. ST505 strains isolated from patients and public baths were distributed along the river in a western part of Toyama Prefecture. SBT and PFGE profiles of 3 clinical isolates were identical with those of 3 environmental isolates from the suspected origins of the infection in each case, respectively. This finding suggested that SBT and PFGE were useful for epidemiological study. Furthermore, by SBT analysis, we identified a clonal group formed only by 7 clinical isolates that are not associated with bathwater, suggesting that they were derived from unrecognized sources.
authors.affiliation: Department of Bacteriology, Toyama Institute of Health, 17-1 Nakataikoyama, Imizu, Toyama, 939-0363, Japan.
authors.forename: Jun-Ichi
authors.initials: J
authors.lastname: Kanatani
authors.forename: Junko
authors.initials: J
authors.lastname: Isobe
authors.forename: Keiko
authors.initials: K
authors.lastname: Kimata
authors.forename: Tomoko
authors.initials: T
authors.lastname: Shima
authors.forename: Miwako
authors.initials: M
authors.lastname: Shimizu
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Kura
authors.forename: Tetsutaro
authors.initials: T
authors.lastname: Sata
authors.forename: Masanori
authors.initials: M
authors.lastname: Watahiki
mesh_terms: D006801:Humans; D007564:Japan / Q000453:epidemiology; D016952:Legionella pneumophila / Q000235:genetics* / Q000302:isolation & purification*; D007877:Legionnaires' Disease / Q000453:epidemiology* / Q000382:microbiology*; D017720:Molecular Epidemiology; D010802:Phylogeny; D015995:Prevalence