Comparison of the Serovars and Characteristics of Salmonella Isolated from Human Feces and Foods in the 1990s and 2010s in Tokyo

Salmonella foodborne disease outbreaks have markedly decreased in recent years, and different Salmonella serovars have been isolated. To clarify the characteristics of Salmonella strains causing annual epidemics and to estimate the source, we conducted a serotyping test on 1,132 human-derived Salmonella isolates in the 1990s and 2010s, and 1,061 food-derived Salmonella isolates in the 2010s in Tokyo. The serovars commonly isolated from human feces in the 1990s and after 2012 were S. Enteritidis, S. Typhimurium, S. Infantis, S. Thompson, and S. Agona. The new main serovars isolated after 2012 were S. Schwarzengrund, S. Enterica serovar 4:i:-, and S. Chester. In contrast, the main serovars detected from foods after 2012 were S. Infantis, S. Schwarzengrund, S. Agona, S. Manhattan, S. Typhimurium, and S. enterica serovar UT: r:1,5. S. Schwarzengrund has recently been frequently isolated. These strains were mainly isolated from chicken meat and offal. It was suggested that the same serovars of human-derived isolates were also isolated from foods, especially chicken meat and offal, and that these were recently an important causative food of Salmonellosis.