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Site-specific Bacterial Chromosome Engineering: ΦC31 Integrase Mediated Cassette Exchange (IMCE)
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Chromosome-encoded CTX-M-3 from Kluyvera ascorbata: a possible origin of plasmid-borne CTX-M-1-derived cefotaximases

María Margarita Rodríguez1, Pablo Power, Marcela Radice

  • 1Cátedra de Microbiología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina.

Antimicrobial Agents and Chemotherapy
|November 25, 2004
PubMed

Insights

A Kluyvera ascorbata strain carries the bla(CTX-M-3) gene on its chromosome, linked to a mobilization structure. Other strains produced the bla(KLUA-9) gene, indicating horizontal gene transfer potential.

Area of Science:

  • Microbiology
  • Genetics
  • Molecular Biology

Background:

  • The bla(CTX-M-3) gene, a significant cause of beta-lactam antibiotic resistance, is typically plasmid-borne.
  • Kluyvera ascorbata is an environmental bacterium that can act as a reservoir for antibiotic resistance genes.

Purpose of the Study:

  • To investigate the genetic context and potential mobilization mechanisms of the bla(CTX-M-3) gene in Kluyvera ascorbata.
  • To identify other beta-lactamase genes present in Kluyvera ascorbata strains.

Main Methods:

  • Whole-genome sequencing of Kluyvera ascorbata strains.
  • Bioinformatic analysis to identify gene structures, open reading frames, and mobile genetic elements.
  • Comparative genomics to analyze gene distribution across strains.

Main Results:

  • A Kluyvera ascorbata strain was found to harbor a chromosomal bla(CTX-M-3) gene.
  • This gene was located within a mobile genetic structure containing an inverted repeat right and a 477-like open reading frame, suggesting a potential for mobilization.
  • Two additional Kluyvera ascorbata strains were identified to possess the bla(KLUA-9) gene.

Conclusions:

  • The chromosomal location of bla(CTX-M-3) in K. ascorbata, along with associated mobile elements, suggests a mechanism for its dissemination.
  • The presence of bla(KLUA-9) in other strains further highlights the genetic diversity and adaptability of beta-lactamase genes within this species.
  • These findings contribute to understanding the evolution and spread of antibiotic resistance genes in environmental bacteria.

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