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Tracking blaCTX-M transmission through transposable elements in uropathogenic and commensal E. coli

Denyss Guilcazo1, Liseth Salinas1, Cristina Chavez1

  • 1Universidad San Francisco de Quito, Colegio de Ciencias Biológicas Ambientales, Instituto de Microbiología, Quito, Ecuador.

Future Microbiology
|January 29, 2025
PubMed
Abstract

Insights

Sequences flanking blaCTX-M genes in E. coli can serve as markers for tracking antimicrobial resistance gene transmission. This study analyzed these sequences in Ecuadorian isolates, revealing unique genetic environments.

Area of Science:

  • Microbiology
  • Genomics
  • Epidemiology

Background:

  • Antimicrobial resistance (AMR) poses a global health threat.
  • Transposable elements carrying beta-lactamase genes like blaCTX-M are key drivers of AMR spread.
  • Understanding the genetic context of these genes is crucial for tracing transmission pathways.

Purpose of the Study:

  • To investigate nucleotide sequences associated with transposable elements carrying blaCTX-M allelic variants.
  • To explore their potential as markers for antimicrobial resistance gene transmission among domestic animals, humans, and the environment.
  • To analyze the genetic environments of blaCTX-M variants in Ecuadorian Escherichia coli isolates.

Main Methods:

  • Whole-genome sequencing was performed on commensal and uropathogenic Escherichia coli isolates from Quito, Ecuador.
  • Nucleotide sequences of abundant blaCTX-M allelic variants (blaCTX-M-27, blaCTX-M-55, and blaCTX-M-65) were analyzed.
  • Phylogenetic analysis was used to determine the genetic environments of the blaCTX-M genes.

Main Results:

  • Commensal and uropathogenic E. coli from Ecuador exhibited identical nucleotide sequences surrounding the blaCTX-M gene.
  • The synteny of these sequences was similar to those found globally.
  • Phylogenetic analysis revealed unique genetic environments for the blaCTX-M genes in Ecuadorian isolates.

Conclusions:

  • Nucleotide sequences flanking blaCTX-M genes can be valuable markers for resolving antimicrobial resistance gene (ARG) transmission pathways.
  • These markers are particularly useful for inter-regional analyses of ARG spread.
  • The findings highlight the potential for using genetic markers to understand the complex dynamics of AMR transmission.
Keywords:
3rd generation cephalosporinsE. coliTransposable elementsUPECantimicrobial resistanceblaCTX-M genecommensalplasmids

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