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<p>The detection rate of CTX-M-27-producing <i>E. coli</i> has increased worldwide in recent years although relatively little is known about the strains and vectors responsible for this increased isolation.</p><p>To explore the evolution of CTX-M-27-producing <i>E. coli</i> in the past 20 years at three levels; genetic structure of the <i>bla</i><sub>CTX−M−27</sub> locus, nature of carrying plasmids and types of host bacteria, we analysed 543 genomes of <i>bla</i><sub>CTX−M−27</sub>-positive <i>E. coli</i> isolated globally from 2003 to 2020.</p><p>Results indicated that hospitalised patients are a major reservoir of <i>bla</i><sub>CTX−M−27</sub> carrying isolates but there are a wide variety of other resistance genes, plasmid replicons and virulence factors carried by CTX-M-27-producing <i>E. coli</i> strains. There was a strong positive correlation between carriage of the <i>bla</i><sub>CTX−M−27</sub> gene and the highly virulent clone-ST131 <i>E. coli</i>. IncF-type plasmids were the most common vector of <i>bla</i><sub>CTX−M−27</sub> transmission with a subtype of F plasmids showing a tropism for specific sequence types of <i>E. coli</i>. The DNA transfer and replicon-stability regions of host plasmids showed evidence for significant evolution over time with deletion and truncation events associated with <i>bla</i><sub>CTX−M−27</sub>-carrying plasmids being stably maintained in specific host sequence types. Moreover, recently isolated <i>bla</i><sub>CTX−M−27</sub>-carrying plasmids were found to contribute to growth of host bacteria suggesting they have evolved to provide benefits to their host. IncF plasmids and the <i>bla</i><sub>CTX−M−27</sub> locus also showed evidence for co-evolution, in particular, “Bridge” co-integrate structures flanked by IS<i>26</i> were found in this study in IncF plasmids.</p><p>Together, our results illustrate that <i>bla</i><sub>CTX−M−27</sub> is present on various plasmids which are associated with epidemic host <i>E. coli</i> and it appears carriage of prevalent IncF <i>bla</i><sub>CTX−M−27</sub>-carrying plasmids are beneficial for the host. Complex genetic structures are under evolutionary pressure which promote the wide spread of <i>bla</i><sub>CTX−M−27</sub> which is a global health threat.</p>

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Pivotal plasmids drive the global spread of CTX-M-27 in Escherichia coli

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年10月9日

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  • Yan Zhang,
  • Yexin Lin,
  • Yingxin Ruan,
  • Jintao Yang,
  • Emma Holden,
  • Heather Felgate,
  • Maria Solsona,
  • Hoyu Liu,
  • Guan Liang,
  • Hongxia Jiang,
  • Mark A. Webber,
  • Chao Zhuo

摘要

The detection rate of CTX-M-27-producing E. coli has increased worldwide in recent years although relatively little is known about the strains and vectors responsible for this increased isolation.

To explore the evolution of CTX-M-27-producing E. coli in the past 20 years at three levels; genetic structure of the blaCTX−M−27 locus, nature of carrying plasmids and types of host bacteria, we analysed 543 genomes of blaCTX−M−27-positive E. coli isolated globally from 2003 to 2020.

Results indicated that hospitalised patients are a major reservoir of blaCTX−M−27 carrying isolates but there are a wide variety of other resistance genes, plasmid replicons and virulence factors carried by CTX-M-27-producing E. coli strains. There was a strong positive correlation between carriage of the blaCTX−M−27 gene and the highly virulent clone-ST131 E. coli. IncF-type plasmids were the most common vector of blaCTX−M−27 transmission with a subtype of F plasmids showing a tropism for specific sequence types of E. coli. The DNA transfer and replicon-stability regions of host plasmids showed evidence for significant evolution over time with deletion and truncation events associated with blaCTX−M−27-carrying plasmids being stably maintained in specific host sequence types. Moreover, recently isolated blaCTX−M−27-carrying plasmids were found to contribute to growth of host bacteria suggesting they have evolved to provide benefits to their host. IncF plasmids and the blaCTX−M−27 locus also showed evidence for co-evolution, in particular, “Bridge” co-integrate structures flanked by IS26 were found in this study in IncF plasmids.

Together, our results illustrate that blaCTX−M−27 is present on various plasmids which are associated with epidemic host E. coli and it appears carriage of prevalent IncF blaCTX−M−27-carrying plasmids are beneficial for the host. Complex genetic structures are under evolutionary pressure which promote the wide spread of blaCTX−M−27 which is a global health threat.