Since 2004, extended-spectrum cephalosporin-resistant Salmonella enterica serovar Typhimurium (S. Typhimurium) isolates have been detected in cattle from Hokkaido, the northern major island of Japan. Extended-spectrum cephalosporin resistance was found to be mediated by CMY-2 β-lactamase encoded by blaCMY-2. Genetic analysis of S. Typhimurium isolate L-3553 indicated that blaCMY-2 is located on a unique 125-kb genomic island, GI-VII-6, consisting of 140 open reading frames. Phylogenetic analysis suggested that S. Typhimurium isolates harbouring GI-VII-6 belong to a genomic lineage that differs from that of other whole-genome-sequenced S. Typhimurium strains. These data indicate that a particular clone of S. Typhimurium harbouring GI-VII-6 has spread among cattle populations in Hokkaido, Japan.
(Bacterial and Parasitic Disease Research Division)
References:
Shahada F. et al (2011) Antimicrob. Agents Chemother. 55:4114-4121