Genetic basis for dissemination of armA.
OBJECTIVE
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.
González-Zorn
Bruno
B
Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, Madrid, Spain. bgzorn@vet.ucm.es
Catalan
Ana
A
Escudero
Jose A
JA
Domínguez
Lucas
L
Teshager
Tirushet
T
Porrero
Concepción
C
Moreno
Miguel Angel
MA
D000617:Aminoglycosides / Q000494:pharmacology; D000818:Animals; D004251:DNA Transposable Elements; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D004755:Enterobacteriaceae / Q000235:genetics / Q000502:physiology; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D029968:Escherichia coli Proteins / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D019143:Evolution, Molecular; D023061:Gene Order; D006801:Humans; D032023:Integrons; D026901:Membrane Transport Proteins / Q000235:genetics; D008780:Methyltransferases / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D010957:Plasmids / Q000235:genetics*; D012336:RNA, Ribosomal, 16S / Q000378:metabolism; D017421:Sequence Analysis
D000617:Aminoglycosides; D004251:DNA Transposable Elements; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D012336:RNA, Ribosomal, 16S; C506767:ArmA protein, E coli; D008780:Methyltransferases