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Updated: Jun 19, 2025

Forward Genetic Approaches in Chlamydia trachomatis
09:03

Forward Genetic Approaches in Chlamydia trachomatis

Published on: October 23, 2013

12.9K

Chlamydia suis undergoes interclade recombination promoting Tet-island exchange

Helena Seth-Smith1, Sankhya Bommana2, Deborah Dean2,3

  • 1Institute of Veterinary Pathology, University of Zurich, Zurich, Switzerland.

BMC Genomics
|July 26, 2024
PubMed
Abstract

Insights

Tetracycline resistance in Chlamydia suis arose from a single horizontal gene transfer event. Interclade recombination of the tetracycline resistance (TetR) island occurred after this event, with variations observed between field and in vitro strains.

Area of Science:

  • Bacterial genomics
  • Antimicrobial resistance evolution
  • Molecular evolution

Background:

  • Chlamydiaceae are obligate intracellular bacteria causing various diseases.
  • Chlamydia suis is unique in naturally acquiring tetracycline resistance (TetR) via a genomic island (Tet-island).
  • The Tet-island is integrated within the invasin-like gene (inv) in C. suis.

Purpose of the Study:

  • To investigate the interclade recombination of the Tet-island in C. suis field strains.
  • To compare recombination patterns between field strains and in vitro-generated recombinants.
  • To understand the evolutionary dynamics of tetracycline resistance acquisition in C. suis.

Main Methods:

  • Comparative genomic analysis of whole genome sequences.
  • Phylogenetic analysis of the invasin-like gene (inv) and the Tet-island.
  • Analysis of recombination patterns in 35 C. suis field strains and 63 in vitro-generated recombinants.

Main Results:

  • The phylogeny of inv more closely mirrored the Tet-island phylogeny than the whole genome, supporting recombination as the transfer mechanism.
  • Significant differences in recombination distribution were observed between in vitro and field strains.
  • Interclade recombination events involving the Tet-island showed greater variability in length downstream compared to upstream.

Conclusions:

  • The study supports a single ancestral horizontal gene transfer event for the Tet-island.
  • Interclade recombination explains the presence of tetracycline resistance in both C. suis clades.
  • Understanding these recombination events is crucial for tracking antimicrobial resistance in Chlamydia.
Keywords:
ChlamydiaChlamydiaceaeAntibiotic resistanceComparative phylogeneticsHomologous recombinationHorizontal gene transferTetracycline

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