Diverse commensal Escherichia coli clones and plasmids disseminate antimicrobial resistance genes in domestic animals and children in a semirural community in Ecuador

Liseth Salinas, Paúl Cárdenas, Timothy J. Johnson, Karla Vasco, Jay Graham, Gabriel Trueba

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

The increased prevalence of antimicrobial resistance (AMR) among Enterobacteriaceae has had major clinical and economic impacts on human medicine. Many of the multidrug-resistant (multiresistant) Enterobacteriaceae found in humans are community acquired, and some of them are possibly linked to food animals (i.e., livestock raised for meat and dairy products). In this study, we examined whether numerically dominant commensal Escherichia coli strains from humans ( n  = 63 isolates) and domestic animals ( n  = 174 isolates) in the same community and with matching phenotypic AMR patterns were clonally related or shared the same plasmids. We identified 25 multiresistant isolates (i.e., isolates resistant to more than one antimicrobial) that shared identical phenotypic resistance patterns. We then investigated the diversity of E. coli clones, AMR genes, and plasmids carrying the AMR genes using conjugation, replicon typing, and whole-genome sequencing. All of the multiresistant E. coli isolates (from children and domestic animals) analyzed had at least 90 or more whole-genome SNP differences between one another, suggesting that none of the strains was recently transferred. While the majority of isolates shared the same antimicrobial resistance genes and replicons, DNA sequencing indicated that these genes and replicons were found on different plasmid structures. We did not find evidence of the clonal spread of AMR in this community: instead, AMR genes were carried on diverse clones and plasmids. This presents a significant challenge for understanding the movement of AMR in a community. IMPORTANCE Even though Escherichia coli strains may share nearly identical phenotypic AMR profiles and AMR genes and overlap in space and time, the diversity of clones and plasmids challenges research that aims to identify sources of AMR. Horizontal gene transfer appears to play a more significant role than clonal expansion in the spread of AMR in this community.

Original languageEnglish (US)
Article numbere00316-19
JournalmSphere
Volume4
Issue number3
DOIs
StatePublished - May 1 2019

Bibliographical note

Funding Information:
Research reported in this publication was supported by the National Institute of Allergy and Infectious Diseases of the National Institutes of Health under award no. R01AI135118. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Publisher Copyright:
© 2019 Salinas et al.

Keywords

  • Antibiotic resistance
  • Clonality
  • Escherichia coli
  • Plasmid analysis

PubMed: MeSH publication types

  • Journal Article
  • Research Support, N.I.H., Extramural

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