Analysis of the molecular evolution of Listeria monocytogenes isolated from Japanese meats and environment.

Food contaminated by Listeria monocytogenes is a problem on a worldwide level because it is a serious food-borne pathogen. Although 3 evolutionary divisions have been reported for L. monocytogenes, the evolution of Japanese isolates has not yet been clarified. Thus, in order to determine the lineage of these Japanese isolates, we classified and conducted phylogenetic analysis of 407 bp (position 1116-1522) of the iap gene derived from 88 isolates from Japanese listeriosis patients, foods and environment. The isolates were classified into 18 types commonly accompanied by serotypes, and the types were divided into 3 lineages. Our results suggest that these Japanese isolates belong to the 3 lineages of L. monocytogenes isolated in other countries.