Genetic basis for dissemination of armA

J Antimicrob Chemother. 2005 Sep;56(3):583-5. doi: 10.1093/jac/dki246. Epub 2005 Jul 18.


Objectives and methods: armA is a novel plasmid-borne 16S rRNA methyltransferase that confers high-level resistance to 4,6-disubstituted deoxystreptamines. Recently, we have isolated from a high-level broad-spectrum aminoglycoside-resistant Escherichia coli animal isolate a plasmid, pMUR050, that bore the armA gene. In order to elucidate the genetic basis for the spread of armA, we have determined the complete nucleotide sequence of pMUR050.

Results: armA was borne by a complex transposon composite flanked by two direct repeats of IS26. The transposon composite included a class one integron with sul1 for resistance to sulphonamides and ant3''9 conferring resistance to spectinomycin-streptomycin, and a macrolide efflux pump and mefE/mel conferring high-level resistance to erythromycin. We identified in GenBank that another plasmid, pCTX-M3, from a Polish Citrobacter freundii human isolate, bore the same genetic structure, including armA.

Conclusions: armA is present in human and animal isolates within a novel transposon composite. Further spread of armA between bacteria of diverse origin is to be expected.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aminoglycosides / pharmacology
  • Animals
  • DNA Transposable Elements*
  • Drug Resistance, Multiple, Bacterial / genetics*
  • Enterobacteriaceae / genetics
  • Enterobacteriaceae / physiology
  • Escherichia coli / drug effects
  • Escherichia coli / genetics*
  • Escherichia coli / isolation & purification
  • Escherichia coli Proteins / drug effects
  • Escherichia coli Proteins / genetics*
  • Escherichia coli Proteins / metabolism
  • Evolution, Molecular
  • Gene Order
  • Humans
  • Integrons
  • Membrane Transport Proteins / genetics
  • Methyltransferases / drug effects
  • Methyltransferases / genetics*
  • Methyltransferases / metabolism
  • Microbial Sensitivity Tests
  • Plasmids / genetics*
  • RNA, Ribosomal, 16S / metabolism
  • Sequence Analysis


  • Aminoglycosides
  • DNA Transposable Elements
  • Escherichia coli Proteins
  • Membrane Transport Proteins
  • RNA, Ribosomal, 16S
  • ArmA protein, E coli
  • Methyltransferases