Salmonella enterica bla(CTX-M-2) and bla(CTX-M-9) plasmid backbones from isolates from Belgium and France were analyzed. The bla(CTX-M-2-)plasmids from both human and poultry isolates were related to the IncHI2 pAPEC-O1-R plasmid, previously identified in the United States in avian Escherichia coli strains; the bla(CTX-M-9) plasmids were closely related to the IncHI2 R478 plasmid.

Controlled shearing of R-factor DNA leads to formation of fragments carrying an antibiotic resistance gene present on, but not expressed by, the intact R-factor. Transformation of CaCl(2)-treated E. coli by such fragments yields an autonomously replicating tetracycline-resistance plasmid (Tc6-5) that contains only a small fraction of the genome of the parent R-factor, and lacks both its fertili...

Scientific analysis of the genus Rickettsia is undergoing a rapid period of change with the emergence of viable genetic tools. The development of these tools for the mutagenesis of pathogenic bacteria will permit forward genetic analysis of Rickettsia pathogenesis. Despite these advances, uncertainty still remains regarding the use of plasmids to study these bacteria in in vivo mammalian models...

INTRODUCTION AND DEFINITIONS ...................................... 361 SOME PROPERTIES OF BACTERIAL PLASMIDS .......................... 362 Chromosomal Integration ............... .................................... 363 Fertility Repression........................................................ 363 Incompatibility ............................................................. 364 Elimination ...

Salmonella naestved strain AHI-21, of calf origin, harbors a conjugative R plasmid of group H1, pTE21, which encodes resistance to chloramphenicol (Cm), tetracycline, streptomycin, and sulfadimethoxine. Escherichia coli strain AHI-1, of pig origin, also harbors a conjugative R plasmid of group I alpha, pTE1, which encodes resistance to chloramphenicol and trimethoprim. When either of these R pl...

Plasmids have been identified in most species of Rickettsia examined, with some species maintaining multiple different plasmids. Three distinct plasmids were demonstrated in Rickettsia amblyommii AaR/SC by Southern analysis using plasmid specific probes. Copy numbers of pRAM18, pRAM23 and pRAM32 per chromosome in AaR/SC were estimated by real-time PCR to be 2.0, 1.9 and 1.3 respectively. Clonin...

A simple approach was used to identify Rhizobium meliloti DNA regions with the ability to convert a nontransmissible vector into a mobilizable plasmid, i.e., to contain origins of conjugative transfer (oriT, mob). RecA-defective R. meliloti merodiploid populations, where each individual contained a hybrid cosmid from an R. meliloti GR4 gene library, were used as donors en masse in conjugation w...

Fifty-four strains of Rhodococcus equi from different clinical sources (mainly horses and pigs) were examined for their plasmid content by two screening methods. Plasmids were detected in 49 of 54 strains. A plasmid of approximately 80 kb was isolated from 21 of 22 isolates from horses and 20 of 28 isolates from pigs, and a 105-kb plasmid was isolated from 7 of 28 isolates from pigs. The 80-kb ...