First description of ColE-type plasmid in Aeromonas spp. carrying quinolone resistance (qnrS2) gene

Lett Appl Microbiol. 2012 Oct;55(4):290-4. doi: 10.1111/j.1472-765X.2012.03293.x. Epub 2012 Aug 28.


Aims: Isolation and full sequence analysis of ColE-type plasmid, which carries the qnrS2 gene.

Methods and results: Quinolone resistance (qnrS2) gene-carrying plasmids were isolated from Aeromonas sobria and Aeromonas hydrophila strains, and plasmid sequencing was achieved by a primer-walking approach. The total sizes of these plasmids (pAQ2-1 and pAQ2-2) were 6900 bp and 6903 bp, respectively, and they were 99·1% identical to each other. The genes (oriV and repA) for plasmid replication were organized similar to the corresponding genes in the ColE2-type plasmids, pAsa3 and pAsa1, isolated from Aeromonas salmonicida subsp. salmonicida, but the gene (mobA) for mobilization was homologue to ColE1-type plasmid (pAsa2) from Aer. salmonicida subsp. salmonicida. Additionally, the qnrS2 gene was part of a mobile insertion cassette element in the plasmid.

Conclusions: Two plasmids were assumed to be the same plasmid, and this identification of a plasmid-mediated qnrS2 gene from the two different strains underlines a possible diffusion of these resistance determinants in an aquaculture system.

Significance and impact of the study: This is the first finding of the ColE-type plasmid carrying the qnrS2 gene.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aeromonas / drug effects
  • Aeromonas / genetics*
  • Animals
  • Aquaculture
  • Characidae / microbiology
  • DNA, Bacterial / genetics
  • Molecular Sequence Data
  • Oryzias / microbiology
  • Plasmids / genetics*
  • Plasmids / isolation & purification
  • Quinolones / pharmacology*
  • Sequence Analysis, DNA


  • DNA, Bacterial
  • Quinolones

Associated data

  • GENBANK/JN315884
  • GENBANK/JN315885