Research Topic: Horizontal gene transfer of antibiotic resistance in selected bacteria in Chinese frog farms
Abstract: ** Lecture will be given in English** (249 words)
Horizontal gene transfer (HGT) enables bacteria to rapidly acquire new traits and to adapt to changing environments. Identifying prominent HGT regions in bacterial genomes can reveal essential genetic mechanisms in microbial evolution and resistome development. We used comparative genomics to identify putative HGT regions in the genomes of 109 antibiotic resistant bacteria isolated from intensive Chinese frog farms in 2019 (old samples). These isolates included Escherichia coli, Edwardsiella tarda, and Citrobacter and Klebsiella species. We identified and defined 174 representative genomic islands (GIs) that were enriched in antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs). Integron-associated GIs were the major ARG hotspots (100% contained ARGs) and carried a significantly greater ARG load than non-integron-associated GIs (39% contained ARGs). These GIs were also detected in sediment samples collected in 2024 (new samples) from frog farms in a 10 km vicinity of the old samples. These integron-associated GIs mediated the transfer of ARGs between different plasmids and between plasmids and the chromosome. Further analysis revealed that genomic islands such as GI38, GI212, and GI285 were widely distributed across different biosamples, habitats, and continents. These results demonstrated that HGT, especially integron-associated GIs can mediate the dissemination and persistence of ARGs across bacterial hosts in intensive frog farms and other habitats. Therefore, understanding ARGs-MGEs-host relationships in resistomes can facilitate the development of effective antibiotic resistance mitigation strategies and advance our knowledge of One Health dynamics.
