title: Molecular Typing of Legionella pneumophila Isolates in the Province of Quebec from 2005 to 2015.
abstract: Legionella is found in natural and man-made aquatic environments, such as cooling towers and hot water plumbing infrastructures. Legionella pneumophila serogroup 1 (Lp1) is the most common etiological agent causing waterborne disease in the United States and Canada. This study reports the molecular characterization of Lp strains during a 10 year period. We conducted sequence-based typing (SBT) analysis on a large set of Lp isolates (n = 284) to investigate the province of Quebec sequence types (STs) distribution in order to identify dominant clusters. From 2005 to 2015, 181 clinical Lp isolates were typed by SBT (141 sporadic cases and 40 outbreak related cases). From the same period of time, 103 environmental isolates were also typed. Amongst the 108 sporadic cases of Lp1 typed, ST-62 was the most frequent (16.6%), followed by ST-213 (10.2%), ST-1 (8.3%) and ST-37 (8.3%). Amongst other serogroups (SG), ST-1327 (SG5) (27.3%) and ST-378 (SG10) (12.2%) were the most frequent. From the environmental isolates, ST-1 represent the more frequent SBT type (26.5%). Unweighted pair group method with arithmetic mean (UPGMA) dendrogram from the 108 sporadic cases of SG1 contains 4 major clusters (A to D) of related STs. Cluster B contains the majority of the strains (n = 61) and the three most frequent STs in our database (ST-62, ST-213 and ST-1). During the study period, we observed an important increase in the incidence rate in Quebec. All the community associated outbreaks, potentially or confirmed to be associated with a cooling tower were caused by Lp1 strains, by opposition to hospital associated outbreaks that were caused by serogroups of Lp other than SG1. The recent major Quebec City outbreak caused by ST-62, and the fact that this genotype is the most common in the province supports whole genome sequencing characterization of this particular sequence type in order to understand its evolution and associated virulence factors.
authors.affiliation: Laboratoire de santé publique du Québec, Institut national de santé publique du Québec, Sainte-Anne-de-Bellevue, Québec, Canada.|Département de microbiologie, infectiologie et immunologie, Université de Montréal, Québec, Canada.|Centre de recherche du centre hospitalier de l'Université de Montréal, Québec, Canada.
authors.forename: Simon
authors.identifier: http://orcid.org/0000-0002-4356-9702
authors.initials: S
authors.lastname: Lévesque
authors.affiliation: Laboratoire de santé publique du Québec, Institut national de santé publique du Québec, Sainte-Anne-de-Bellevue, Québec, Canada.
authors.forename: Cindy
authors.initials: C
authors.lastname: Lalancette
authors.affiliation: Public Health Agency of Canada, National Microbiology Laboratory, Winnipeg, Manitoba, Canada.
authors.forename: Kathryn
authors.initials: K
authors.lastname: Bernard
authors.affiliation: Public Health Agency of Canada, National Microbiology Laboratory, Winnipeg, Manitoba, Canada.
authors.forename: Ana Luisa
authors.initials: AL
authors.lastname: Pacheco
authors.affiliation: Laboratoire de santé publique du Québec, Institut national de santé publique du Québec, Sainte-Anne-de-Bellevue, Québec, Canada.|Département de médecine sociale et préventive, École de santé publique de l'Université de Montréal, Québec, Canada.
authors.forename: Réjean
authors.initials: R
authors.lastname: Dion
authors.affiliation: Laboratoire de santé publique du Québec, Institut national de santé publique du Québec, Sainte-Anne-de-Bellevue, Québec, Canada.|Centre de recherche en infectiologie de l'Université Laval, Québec, Canada.
authors.forename: Jean
authors.initials: J
authors.lastname: Longtin
authors.affiliation: Département de microbiologie, infectiologie et immunologie, Université de Montréal, Québec, Canada.|Centre de recherche du centre hospitalier de l'Université de Montréal, Québec, Canada.
authors.forename: Cécile
authors.initials: C
authors.lastname: Tremblay
mesh_terms: D016000:Cluster Analysis; D006801:Humans; D015994:Incidence; D016952:Legionella pneumophila / Q000145:classification* / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D007877:Legionnaires' Disease / Q000453:epidemiology* / Q000382:microbiology; D058889:Molecular Typing / Q000379:methods*; D010802:Phylogeny; D011792:Quebec / Q000453:epidemiology; D017422:Sequence Analysis, DNA / Q000379:methods*; D065288:Serogroup