New Endemic Legionella pneumophila Serogroup I Clones, Ontario, Canada

摘要

The water-borne pathogen Legionella pneumophila serogroup 1 (Lp1) is the most commonly reported etiologic agent of legionellosis. To examine the genetic diversity, the long-term epidemiology, and the molecular evolution of Lp1 clinical isolates, we conducted sequence-based typing on a collection of clinical isolates representing 3 decades of culture-confi rmed legionellosis in Ontario, Canada. Analy-sis showed that the population of Lp1 in Ontario is highly diverse and combines lineages identifi ed worldwide with lo-cal strains. Identical types were identifi ed in sporadic and outbreak-associated strains. In the past 15 years, the inci-dence of some lineages distributed worldwide has tended to decrease, and local endemic clones and lineages have emerged. Comparative geographic distribution analysis suggests that some lineages are specifi c to eastern North America. These fi ndings have general clinical implications for the study of Lp1 molecular evolution and for the identifi -cation of Lp1 circulating strains in North America