DNA Sequence Analysis of Regions Surrounding bla_CMY-2 from Multiple Salmonella Plasmid Backbones

Authors

• W.P. Giles, University of Nebraska-Lincoln
• Andrew K. Benson, University of Nebraska-LincolnFollow
• M.E. Olson, University of Nebraska Medical Center, Omaha, Nebraska
• Robert W. Hutkins, University of Nebraska-LincolnFollow
• J.M. Whichard, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia
• P.L. Winokur, University of Iowa and Veterans Affairs Medical Center, Iowa City, Iowa
• P.D. Fey, University of Nebraska Medical Center, Omaha, Nebraska

Document Type

Article

Date of this Version

August 2004

Comments

Published in ANTIMICROBIAL AGENTS AND CHEMOTHERAPY, Aug. 2004, p. 2845–2852 Vol. 48, No. 8. Copyright © 2004, American Society for Microbiology. Used by permission.

Abstract

The emergence in the United States of resistance to expanded-spectrum cephalosporin (e.g., ceftriaxone) within the salmonellae has been associated primarily with three large (>100-kb) plasmids (designated types A, B, and C) and one 10.1-kb plasmid (type D) that carry the bla_CMY-2 gene. In the present study, the distribution of these four known bla_CMY-2-carrying plasmids among 35 ceftriaxone-resistant Salmonella isolates obtained from 1998 to 2001 was examined. Twenty-three of these isolates were Salmonella enterica serotype Newport, 10 were Salmonella enterica serotype Typhimurium, 1 was Salmonella enterica serotype Agona, and 1 was Salmonella enterica serotype Reading. All 23 serotype Newport isolates carried a type C plasmid, and 5, 4, and 1 serovar Typhimurium isolate carried type B, A, and C plasmids, respectively. Both the serotype Agona and serotype Reading isolates carried type A plasmids. None of the isolates carried a type D plasmid. Hybridization data suggested that plasmid types A and C were highly related replicons. DNA sequencing revealed that the region surrounding bla_CMY-2 was highly conserved in all three plasmid types analyzed (types B, C, and D) and was related to a region surrounding bla_CMY-5 from the Klebsiella oxytoca plasmid pTKH11. These findings are consistent with a model in which bla_CMY-2 has been disseminated primarily through plasmid transfer, and not by mobilization of the gene itself, to multiple Salmonella chromosomal backbones.