DNA sequence analysis of the composite plasmid pTC conferring virulence and antimicrobial resistance for porcine enterotoxigenic Escherichia coli

Péter Z. Fekete, Elzbieta Brzuszkiewicz, Gabriele Blum-Oehler, Ferenc Olasz, Mónika Szabó, Gerhard Gottschalk, Jörg Hacker, Béla Nagy

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In this study the plasmid pTC, a 90. kb self-conjugative virulence plasmid of the porcine enterotoxigenic Escherichia coli (ETEC) strain EC2173 encoding the STa and STb heat-stable enterotoxins and tetracycline resistance, has been sequenced in two steps. As a result we identified five main distinct regions of pTC: (i) the maintenance region responsible for the extreme stability of the plasmid, (ii) the TSL (toxin-specific locus comprising the estA and estB genes) which is unique and characteristic for pTC, (iii) a Tn. 10 transposon, encoding tetracycline resistance, (iv) the tra (plasmid transfer) region, and (v) the colE1-like origin of replication. It is concluded that pTC is a self-transmissible composite plasmid harbouring antibiotic resistance and virulence genes. pTC belongs to a group of large conjugative E. coli plasmids represented by NR1 with a widespread tra backbone which might have evolved from a common ancestor. This is the first report of a completely sequenced animal ETEC virulence plasmid containing an antimicrobial resistance locus, thereby representing a selection advantage for spread of pathogenicity in the presence of antimicrobials leading to increased disease potential.

Original languageEnglish
Pages (from-to)4-9
Number of pages6
JournalInternational Journal of Medical Microbiology
Issue number1
Publication statusPublished - Jan 1 2012



  • Enterotoxigenic Escherichia coli (ETEC)
  • Sequence analysis
  • Toxin-specific locus (TSL)
  • Virulence and antibiotic resistance plasmid

ASJC Scopus subject areas

  • Microbiology
  • Microbiology (medical)
  • Infectious Diseases

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