Plasmid-mediated transfer of CTX-M-55 extended-spectrum beta-lactamase among different strains of Salmonella and Shigella spp. in the Republic of Korea.

We screened 10 CTX-M-55-producing Shigella and Salmonella isolates from a national surveillance in Korea. The blaCTX-M-55 was located on the IncI1 (n=5), IncA/C (n=4) and IncZ (n=1) plasmids, downstream of ISEcp1, IS26-ISEcp1 and ISEcp1-IS5 sequences, respectively. These results indicate that CTX-M-55 has disseminated to other bacteria by lateral plasmid transfer.