Article

Characterization of Plasmids Carrying CMY-2 from Expanded-Spectrum Cephalosporin-Resistant Salmonella Strains Isolated in the United States between 1996 and 1998

University of Nebraska at Omaha, Omaha, Nebraska, United States
Antimicrobial Agents and Chemotherapy (Impact Factor: 4.45). 06/2002; 46(5):1269-72. DOI: 10.1128/AAC.46.5.1269-1272.2002
Source: PubMed

ABSTRACT Sequencing of DNA from 15 expanded-spectrum cephalosporin (e.g., ceftriaxone)-resistant Salmonella isolates obtained in the United States revealed that resistance to ceftriaxone in all isolates was mediated by cmy-2. Hybridization patterns revealed three plasmid structures containing cmy-2 in these 15 isolates. These data suggest that the spread of cmy-2 among Salmonella strains is occurring through mobilization of the cmy-2 gene into different plasmid backbones and consequent horizontal transfer by conjugation.

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    • "Plasmid-mediated β-lactamases were classified into six genetic clusters and blaCMY was the most prevalent one. The blaCMY has been found on plasmid of sizes variable for 7 to 180 kb [5] [6]. Plasmid-mediated quinolone resistance (PMQR) was first discovered in a clinical isolate of Kelebsiella penemoniae from Birmingham, Albama collected in 1998 by Martinez-Martinez. "
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    • "An attenuator-like structure – similar to that of inducibly expressed catA genes – was detected upstream of the cmlA gene [123]. During the last decade, a number of genes closely related to or indistinguishable from cmlA – and all assigned to group E-1 – have been identified in a wide variety of Gram-negative bacteria, including E. coli [126], S. Typhimurium [127], Klebsiella pneumoniae [128] [129], and P. aeruginosa [130] [131] [132], but also from an uncultured eubacterium [103] (Table 3). E. coli strains carrying the gene cmlA were reported to exhibit MICs of Cm of P 32 to >256 mg l À1 and MICs of Ff of 6 8 to 64 mg l À1 [133] [134]. "
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    • "Although the plasmids obtained from Salmonella strains were not identical (Fig. 1, panel (a), lanes 2–8), restriction analysis suggested that they were similar to one another but different from the E. coli BN10660 plasmid (Fig. 1, panel (a), lane 1). Plasmid profiles were hybridized with specific probes as described previously [4] [19]. These included the bla CMY-2 gene and the orfA 0 –floR–orfA gene cluster, the latter obtained from the cloned floR plasmid pEF03 (Fig. 1). "
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