Rebekka Koeck (MUMC+)

Summary of presentation:
Extended-spectrum beta-lactamase- and carbapenemase-producing Enterobacteriaceae (ESBL-E and CPE) are major drivers of difficult-to-treat infections in healthcare settings. Because antimicrobial resistance (AMR) can emerge from community and animal reservoirs, understanding how resistance determinants circulate across domains within a One-Health framework is essential for anticipating their impact on patient care. The recent i-4-1-health project sampled humans (hospitalised patients, nursing home residents and daycare children) and animals (broilers and pigs) in the Dutch-Belgian border region. Although we only observed sporadic clonal transmission between humans and animals, the movement of plasmids carrying resistance genes may still facilitate the introduction of clinically relevant AMR into human populations. Therefore, our aim was to assess how plasmid dissemination contributes to resistance spread across domains.

450 Enterobacteriaceae isolates were short-read (Illumina) and long-read (Oxford Nanopore Technologies) sequenced to construct hybrid assemblies (Unicycler). Complete plasmids were clustered using Pling, MOB-suite and PlasmidSimilarity and annotated for AMR genes and plasmid replicons (ABRicate).

Only one clonally related pair of E. coli isolates spanned multiple host domains (human and broiler), suggesting potential transmission. 1274 complete plasmids were recovered from the 450 isolates. These plasmids clustered into 153 sub-communities, of which 37 (24%) included human and animal plasmids. The largest AMR plasmid cluster comprised 19 plasmids from humans and broilers. This is an IncI1_1_Alpha plasmid cluster carrying multiple AMR genes: blaCTX-M-1_1, sul2_2, tet(A)_6, aadA5_1 and dfrA17_1.

While the i-4-1-health project only revealed limited clonal transmission between domains, plasmid analysis identified several multi-domain clusters that could represent inter-domain plasmid transmission events. Such events have the capacity to introduce clinically relevant resistance into human populations and highlight the importance of mobile genetic elements in resistance spread within a One-Health context. Utilising plasmid-level surveillance in a One-Health setting may facilitiate early detection of emerging resistance mechanisms and thereby inform more effective prevention of AMR transmission.