Analyse génétique de l'espèce Kingella Kingae : phylogénie, physiopathologie et résistance aux antibiotiques

Kingella kingae is a normal agent of the oropharyngeal microbiota and the first pathogen of osteoarticular infections (OAI) in young children. We aimed to characterize the genetic organization of the species and to better understand the pathophysiology of K. Kingae infections and the epidemiology of the antibiotic resistance. We collected 324 isolates from intercontinental origin and developed a multilocus sequence typing schema revealing a large genetic diversity of the species. Five sequence type complexes were predominant and intercontinentally distributed, of which certain were associated with a clinical syndrome, such as OAI or endocarditis. Moreover, development of an animal model highlighted that some strains had different profiles of virulence. Throat samples during K. Kingae OAI confirmed that the oropharynx is the portal of entry for this pathogen and showed that viral infection, especially with human rhinovirus, was significantly associated with them. The rare beta-lactamase producing strains had a clonai distribution and the same clone was present in the USA and Iceland. We isolated the first beta-lactamase producer in continental Europe with the first chromosomal location of the biarEm_i gene. We described the phylogeny of the species and attempted to correlate the genotype with the clinical origin and the experimental virulence of the strains. The tools that we developed combined with the future sequencing of targeted strains would allow identifying new virulence factors to better understand the pathophysiology of K. Kingae. The epidemiology of the antibiotic resistance within this species suggests the risk of emergence of beta-lactamase producing strains.