Streptococcus suis as a reservoir of antibiotic resistance genes carried by Mobile Genetic Elements transferring by conjugation
Résumé
Streptococcus suis is a zoonotic pathogen that leads to high economic losses in the pig industry and is responsible for serious infections in people working in close contact with infected animals or contaminated meat. Increasing reports of antimicrobial resistance (AMR) in this species suggest that this species could be a reservoir of AMR genes spreading to other species by horizontal gene transfer. The thorough in silico analysis of 214 genomes of S. suis strains belonging to 27 serotypes revealed a huge number of chromosomal mobile genetic elements transferring by conjugation: 496 Integrative Conjugative Elements (ICEs) and 457 Integrative Mobilizable Elements (IMEs). A high diversity of integration sites was detected as well as a high mosaicism of these elements. Their high plasticity results from an accretion in tandem with other ICEs, recombination between elements and module exchanges but also integration of other elements (ICE or IME) inside ICEs. Many of these genetic elements carry AMR genes thus indicating a key role of these chromosomal mobile genetic elements in the dissemination of antimicrobial resistance in S. suis and also likely towards other bacterial species.