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Antimicrobial Agents and Chemotherapy, July 2008, p. 2581-2592, Vol. 52, No. 7
0066-4804/08/$08.00+0 doi:10.1128/AAC.01540-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Unité des Agents Antibactériens, Institut Pasteur, Paris, France,1 Cliniques Universitaires UCL de Mont-Godinne, Yvoir, Belgium,2 Centre d'Etudes Pharmaceutiques, Châtenay-Malabry, France,3 Plate-forme Intégration et Analyse Génomique, Institut Pasteur, Paris, France4
Received 29 November 2007/ Returned for modification 2 February 2008/ Accepted 27 April 2008
Self-transferable IncFI plasmid pIP1206, isolated from an Escherichia coli clinical isolate, carries two new resistance determinants: qepA, which confers resistance to hydrophylic fluoroquinolones by efflux, and rmtB, which specifies a 16S rRNA methylase conferring high-level aminoglycoside resistance. Analysis of the 168,113-bp sequence (51% G+C) revealed that pIP1206 was composed of several subregions separated by copies of insertion sequences. Of 151 open reading frames, 56 (37%) were also present in pRSB107, isolated from a bacterium in a sewage treatment plant. pIP1206 contained four replication regions (RepFIA, RepFIB, and two partial RepFII regions) and a transfer region 91% identical with that of pAPEC-O1-ColBM, a plasmid isolated from an avian pathogenic E. coli. A putative oriT region was found upstream from the transfer region. The antibiotic resistance genes tet(A), catA1, blaTEM-1, rmtB, and qepA were clustered in a 33.5-kb fragment delineated by two IS26 elements that also carried a class 1 integron, including the sulI, qacE
1, aad4, and dfrA17 genes and Tn10, Tn21, and Tn3-like transposons. The plasmid also possessed a raffinose operon, an arginine deiminase pathway, a putative iron acquisition gene cluster, an S-methylmethionine metabolism operon, two virulence-associated genes, and a type I DNA restriction-modification (R-M) system. Three toxin/antitoxin systems and the R-M system ensured stabilization of the plasmid in the host bacteria. These data suggest that the mosaic structure of pIP1206 could have resulted from recombination between pRSB107 and a pAPEC-O1-ColBM-like plasmid, combined with structural rearrangements associated with acquisition of additional DNA by recombination and of mobile genetic elements by transposition.
Published ahead of print on 5 May 2008.
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