Quantitative Analysis and Characteristics of <i>Salmonella</i> from Retail Chicken Meat Products in Japan

From October 2020 to February 2021, a total of 95 retail chicken meat products from 39 retail meat shops in Tokyo Metropolis and Kanagawa Prefecture, Japan, were collected and examined for the prevalence of Salmonella to assess public health implications. If a sample tested positive for Salmonella, a quantitative analysis was performed using the three-tube most probable number (MPN) method. Of 95 retail chicken meat products, Salmonella was isolated from 30 samples (31.6%). The levels of Salmonella contamination ranged from <0.3 to 4.3 MPN/g. The most frequent level was <0.3 MPN/g (63.3%). Of the 33 Salmonella strains isolated, four serotypes were identified: S. Schwarzengrund (60.6%), S. Infantis (24.2%), S. Agona (12.1%), and S. Manhattan (3.0%). Multilocus sequence typing (MLST) analysis classified most S. Schwarzengrund isolates into sequence type (ST) 241, the same ST found in chicken meat in Japan, except for one isolate. Of the 33 Salmonella isolates, 29 (87.9%) were antibiotic resistant. Twenty-six isolates (78.8%) showed multidrug resistance to two or more antibiotics. Therefore, these results indicate that retail chicken meat products in Japan are an important source of Salmonella infection in humans and that Salmonella contamination in retail chicken products seems to originate from chicken meat.