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Antimicrobial Agents and Chemotherapy, May 2009, p. 1808-1816, Vol. 53, No. 5
0066-4804/09/$08.00+0 doi:10.1128/AAC.00451-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
Chromosomal Integration of the Extended-Spectrum β-Lactamase Gene blaCTX-M-15 in Salmonella enterica Serotype Concord Isolates from Internationally Adopted Children
Laëtitia Fabre,1,
Aurélia Delauné,1,
Emmanuelle Espié,2
Karin Nygard,3
Maria Pardos,1
Lucette Polomack,1
Françoise Guesnier,1
Marc Galimand,4
Jørgen Lassen,3 and
François-Xavier Weill1*
Institut Pasteur, Centre National de Référence des Salmonella, Laboratoire des Bactéries Pathogènes Entériques, Paris, France,1 Institut de Veille Sanitaire, Saint-Maurice, France,2 Norwegian Institute of Public Health, Division of Infectious Disease Control, Oslo, Norway,3 Institut Pasteur, Unité des Agents Antibactériens, Paris, France4
Received 4 April 2008/ Returned for modification 30 May 2008/ Accepted 19 February 2009
We report the emergence of Salmonella enterica isolates of serotype Concord (and its monophasic variant 6,7:l,v:-) producing the extended-spectrum β-lactamases (ESBLs) SHV-12 and CTX-M-15 in France and Norway between 2001 and 2006 (43 in France and 26 in Norway). The majority of these isolates were from adopted children from Ethiopia, most of whom were healthy carriers. Several symptomatic secondary cases were found in the adoptive families and health care facilities in France. Serotype Concord isolates collected before 2003 produced SHV-12 encoded on a 340-kb conjugative plasmid of replicon IncI1. Isolates collected after 2003 produced CTX-M-15. We detected two conjugative plasmids carrying blaCTX-M-15. One plasmid, approximately 300 kb in size, was positive for the IncHI2 replicon and the plasmid-mediated quinolone resistance gene qnrA1. The other plasmid, from one of the earliest CTX-M-15-producing isolates collected, was a fusion plasmid with IncY and IncA/C2 replicons and was 200 kb in size. However, we showed, using Southern hybridization of I-CeuI-digested chromosomal DNA and S1 nuclease analysis of plasmid DNA, that most isolates had a blaCTX-M-15 gene located on chromosomal DNA. Analysis of the flanking regions of the chromosomally located blaCTX-M-15 gene by cloning revealed an ISEcp1 truncated by an intact IS26 upstream from the blaCTX-M-15 gene and a truncated orf477 gene downstream from blaCTX-M-15. We found regions beyond the IS26 and the orf477 genes that were derived from IncA/C2 plasmids, suggesting the chromosomal integration of part of the blaCTX-M-15-carrying IncY and IncA/C2 fusion plasmid from early CTX-M-15-producing isolates.
* Corresponding author. Mailing address: Centre National de Référence des Salmonella, Laboratoire des Bactéries Pathogènes Entériques, Institut Pasteur, 28 rue du Docteur Roux, 75724 Paris cedex 15, France. Phone: 33-(0)1 45 68 83 45. Fax: 33-(0)1 45 68 88 37. E-mail: fxweill{at}pasteur.fr
Published ahead of print on 9 March 2009.
L.F. and A.D. contributed equally to this work.
Antimicrobial Agents and Chemotherapy, May 2009, p. 1808-1816, Vol. 53, No. 5
0066-4804/09/$08.00+0 doi:10.1128/AAC.00451-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
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