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14:49
Associated Chromosome Trap for Identifying Long-range DNA Interactions
Published on: April 23, 2011
DNA sequence analysis of regions surrounding blaCMY-2 from multiple Salmonella plasmid backbones
W P Giles1, A K Benson, M E Olson
1Department of Biology, University of Nebraska--Lincoln, Nebraska, USA.
Antimicrobial Agents and Chemotherapy
|July 27, 2004
Summary
Ceftriaxone resistance in Salmonella is mainly due to the blaCMY-2 gene on plasmids. This study found specific plasmid types (A, B, C) linked to Salmonella serotypes, suggesting plasmid transfer drives resistance spread.
Area of Science:
- Microbiology
- Molecular Biology
- Antimicrobial Resistance
Background:
- Emergence of ceftriaxone resistance in Salmonella in the US is a significant public health concern.
- Resistance is primarily linked to the blaCMY-2 gene located on large plasmids (types A, B, C) and a smaller plasmid (type D).
Purpose of the Study:
- To investigate the distribution of four known blaCMY-2-carrying plasmids among ceftriaxone-resistant Salmonella isolates.
- To understand the dissemination mechanisms of blaCMY-2 in Salmonella serotypes.
Main Methods:
- Analysis of 35 ceftriaxone-resistant Salmonella isolates collected between 1998 and 2001.
- Plasmid typing (A, B, C, D) for blaCMY-2 gene carriage.
- DNA sequencing and hybridization to analyze the blaCMY-2 region and plasmid relatedness.
Main Results:
- Salmonella enterica serotype Newport isolates (n=23) predominantly carried type C plasmids.
- Salmonella enterica serotype Typhimurium isolates (n=10) carried types A, B, and C plasmids.
- Serotypes Agona and Reading carried type A plasmids; no isolates carried type D plasmids. Plasmid types A and C showed high relatedness.
Conclusions:
- The blaCMY-2 gene is primarily disseminated through horizontal plasmid transfer among diverse Salmonella serotypes.
- The conserved blaCMY-2 region across different plasmid types suggests a common origin or evolutionary pathway.
- Resistance spread is driven by plasmid mobility rather than independent gene mobilization to various Salmonella genetic backgrounds.
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