Genomic investigation of nosocomial-associated legionellosis clusters

Legionella pneumophila is the causative agent of legionellosis, which ranges from a mild, flu-like illness called Pontiac fever to a serious and potentially life-threatening pneumonia known as Legionnaires disease (LD). While the majority of cases are community-acquired, LD is also an important cause of hospital-acquired pneumonia and nosocomial-associated cases are thought to be increasing. The majority of cases are linked to the aspiration of contaminated drinking water although decorative fountains, humidifiers and cooling towers have also been implicated in some cases. This study uses whole genome sequencing (WGS) to investigate several nosocomial-associated clusters of LD caused by L. pneumophila serogroup 1, sequence type (ST) 1. It aims to investigate the links between the patients and the hospitals, as well as understand the diversity and evolution of the hospital populations within the context of the global ST1 phylogeny.