{
  "id": 13009592,
  "title": "Chromosomal integration of blaCTX-M redefines the evolutionary trajectory of antibiotic resistance in E. coli through lineage-structured expansion",
  "url": "https://urgent.news/2026/10/08/chromosomal-integration-of-blactx-m-redefines-the-evolutionary",
  "topic": "health",
  "section": "Health & Medicine",
  "published": "2026-10-08T00:00:00.000Z",
  "source": {
    "name": "bioRxiv",
    "slug": "biorxiv",
    "url": "https://www.biorxiv.org/content/10.64898/2026.10.07.757360v1?rss=1"
  },
  "original_language": "en",
  "account": "A global CTX-M pandemic, driven by plasmids, has recently shown evidence of chromosomal integration of blaCTX-M in E. coli, according to a study analyzing 451,174 publicly available E. coli genomes. Of the 2,269 CTX-M-E. coli long-read or hybrid assemblies, 33.5% contained at least one chromosomally integrated blaCTX-M gene. This chromosomal integration was strongly correlated with the E. coli lineage and the specific CTX-M variant, reaching 68.5% in the ST38 lineage and 43.9% in the ST131 lineage. The integration rates varied between subclades of ST131, indicating a recent acceleration in the ST131-C2 subclade. In addition to the blaCTX-M gene, these chromosomal integrations frequently included other resistance genes, with architectures largely inherited from plasmid-borne structures. The ISEcp1- and IS26-mediated integrations occurred throughout the entire E. coli chromosome without any spared zones. The chromosomal integration of blaCTX-M is a widespread and lineage-structured component of the CTX-M pandemic, providing stable vertical inheritance that complements or may even replace plasmid-mediated dissemination in successful ESBL-E. coli clones.",
  "summary": "The global CTX-M pandemic is considered a plasmid-driven phenomenon, yet chromosomal integration of blaCTX-M has been reported in various settings. Screening 451,174 publicly available E. coli genomes and retaining 2,269 CTX-M-E. coli long-read or hybrid assemblies, we found that 33.5% carried at least one chromosomally integrated blaCTX-M. Chromosomal integration was strongly structured by E.…",
  "key_points": [],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}