R1767, an example of the evolution of resistance plasmids

The Salmonella R-factor system R1767 undergoes frequent rearrangement of its plasmid components. The flux of genetic material within this plasmid system depends on a combination of illegitimate and homologous recombination. The presence of several copies of IS160 and two multiresistance transposons, Tn2410 and Tn2411, are substantial reasons for the observed variations.